Articles

A house with a basement, a ground floor and an attic is not one flat drawing — it is several layers stacked on top of each other. Most floor plan apps solve this by showing one floor at a time, but the basement often only comes along if you actively add it.

Some home-scanning apps guess the room type from the furniture they recognise during the scan — a stove means kitchen, a bathtub means bathroom. It is a suggestion, not a verdict, and you must always be able to correct it.

A shared wall between two rooms has two sides, and those two sides belong to two different rooms. On a digital floor plan they can easily have their own colour each, even though it's the same physical wall.

You ask an AI chat to furnish the living room, and it answers with a list of furniture and placements. The question is whether that list can turn into something you can see on your own drawing — or whether it just stays as text.

No. Neither a LiDAR scan nor a camera can tell whether a door is left- or right-hinged, or whether it opens in or out. That is something you choose yourself — and there is a good reason it cannot be guessed reliably.

Yes, if the phone has a LiDAR sensor and you scan the rooms one at a time. The model is built up from the individual scans, stacked floor by floor — but it is only ever as complete as your scans are.

Some home-scanning apps can read an approximate wall colour from the photos taken during a LiDAR scan, using the depth data to sort out furniture and views from the wall itself. It's a suggested colour, not a calibrated measurement.

Yes — export the model as STL, scale it to 1:100 or 1:50, and print one floor at a time with the ceiling off, so you can see into the rooms.

Yes — and it is usually the right call if something went wrong along the way. A flawed scan rarely gets better from being patched up afterwards; it usually gets better from being done again, while you are still standing in the room.

Most rooms SHOULD be square, and a small nudge from the app makes them so. But some rooms genuinely aren't square — and then that snapping has to be switchable, or you end up drawing a lie.

Yes. A drawn home is a fully valid starting point, and you can scan rooms into it afterwards as you get to them. Here is the order that causes the least rework.

Yes — but a 3D furniture placement is a sketch of whether something fits and looks right, not a guarantee. It tells you something a floor plan can't: how a room FEELS with the sofa in place. It doesn't tell you whether your actual sofa has exactly the dimensions the model uses.

You have three or four AI-generated interior design ideas for a room and now need to show them to a partner, a contractor, or just keep them while you decide. A PDF that gathers images, wishes and measurements onto a few pages is easier to share and keep than screenshots scattered through an AI chat.

Yes — if the measurements exist as a CSV file, they can be opened straight away in Excel, Numbers or Google Sheets. It's the easiest route from a list of measurements to a spreadsheet you can keep working in yourself.

One home you live in. Several drawings you're weighing up: a house you're viewing, a dream renovation, an old plan you want to compare against. They shouldn't sit on top of each other — they should be able to sit alongside each other, each on its own.

Often, yes — if the old floor is dry, solid and flat within 2-3 mm over a 2-metre straightedge. But the floor rises 9-20 mm, and that hits doors, steps and appliances.

Yes, but only as a starting point: the listing's floor plan correctly shows which rooms exist and where they sit — the measurements you need to get from somewhere else.

Only partly. Photos remember what's in a room — but a photo without a known measurement in frame can't tell you how big anything is.

Yes. If you have an old drawing, a previous scan, or just the house's outer dimensions, three check measurements per floor can replace measuring every single room.

Yes, if the phone has LiDAR. Then you can scan the piece on the spot and get width, depth and height without a tape measure, without asking a member of staff, and without writing numbers on a slip of paper you will lose again.

Yes, but most apps start them out as fixed markers of where the piece stood during the scan — not as free objects. You typically need to detach a scanned piece of furniture with an initial tap before it can be dragged around like the rest of the furnishings.

Yes — sign in on both devices with the same Apple ID, and the homes sync through your own private iCloud automatically.

No — use it to plan, but always measure the room yourself before you order. A listing's floor plan usually has no scale and no one standing behind the numbers, and a kitchen ordered 5 cm wrong can't be fixed afterwards.

Yes — but only as a hint. A digital colour preview shows you the shape and spread of the colour in the room. The exact shade, the sheen and how the light plays on the wall you can only see once paint is on the actual wall.

A 3D model of a home can often be embedded directly into another website — an estate agent's page, a listing, your own portfolio — so visitors can rotate and zoom without ever leaving the page. Here is how it works, and what it takes.

Technically, yes — but ask the agent or seller first, and keep the scan to the room's surfaces rather than other people's belongings.

Yes. Scanned and drawn rooms live side by side in the same home, and the areas are added together across both. Here's how to split the home up, and where the seam needs to sit.

Yes — either by mocking it up on a photo, trying it in a 3D model of the room, or using tape and paper straight on the wall. All three methods solve the same problem: it's hard to picture size and placement while the artwork is still hanging in the shop or sitting in an online product photo.

You cannot see who clicked a shared link — but you can often see how many times it happened, and when last. Here is the difference between what a good sharing feature shows you, and what it deliberately doesn't.

Yes — if the floor plan shows the actual clearance between the furniture and the wall corners in metres, not just a picture you have to judge by eye. Then you can see whether there's 40 cm or 90 cm left before you order anything.

Yes, a 3D model of your own room can show you direction and pattern before you order. But the screen lies about colour and sheen, and it does not know the price of waste. Use it to choose direction — use a physical sample to choose the shade.

Yes, if you have real measurements for both the furniture and the new home. A tape measure and a floor plan can settle it on paper — a digital floor plan with the furniture placed makes it faster and easier to try several arrangements before moving day arrives.

Yes — but only if the PDF is actually written in his language, not just yours. Here is what it takes for a drawing to be read and understood by someone who doesn't speak your native language.

A digital floor plan doesn't start out knowing what a wall is made of — only where it stands, and how thick it is. Material is a choice you set yourself, and it can be done wall side by wall side, just like colour.

Yes, a lightweight partition wall goes up fast. The hard part is the window: each new room needs daylight and a way out — otherwise it is not a room at all.

Yes, but a facade is harder to judge digitally than an indoor wall: it is always seen in changing daylight, at a distance, and alongside neighbours and surroundings. A digital preview shows you the shape. The weather, the patina and the local context you still have to imagine yourself.

Yes, if you have a scaled floor plan of the home. Then you can place the piece at the right scale, move it around and see straight away whether it fits — instead of guessing with a tape measure and your own sense of distance.

Yes. Most of the furniture measurements you need are already on the price tag or the product's website — width and depth are enough to plan with, and you can often skip the height entirely.

If you have been editing a floor plan for a while — moving walls, removing one, changing colours — and regret the whole thing, the question is whether there is a shortcut back to the starting point, without scanning the home again.

A line on paper and a felt distance are two different things. Walking into your own drawing at 1:1 scale, before a wall has moved or a room has been rebuilt, reveals mistakes a square-metre figure would never have shown.

Yes — if the home has been scanned with LiDAR, several apps can drop you into the rooms in first person and let you walk around yourself, instead of just rotating a 3D model from outside. That is a different thing from looking at a floor plan, and it answers questions numbers can't.

Yes — most home scanning apps let you attach photos to each room, whether they were just taken with the camera or pulled from the photo library, including a realtor's photos from a listing.

Yes — and an iPad is actually the best surface to draw a home on, even if your iPad doesn't have LiDAR and can never scan a room.

Yes — graph paper at 1:50 is the oldest, and still one of the most reliable, ways to make a measured floor plan. Here is the method, square by square.

Yes — but the shower decides everything. It needs around 2.10 m of headroom, while the toilet and basin can move further out under the slope. Here are the heights that decide what can go where.

If only the bathroom is being renovated, there is no reason for a quote to cover the walls and floors of the whole house. Most digital takeoff tools let you choose which rooms to include — but you usually have to actively deselect the rest yourself.

The so-called dollhouse view — where the roof and ceilings are hidden so you look straight down into the rooms — is one of the most used features in home viewers. It only requires switching one thing off: the ceiling.

Yes. An iPhone without Pro in its name cannot scan the room, but it can draw it — and a drawn floor plan is every bit as measured as a scanned one, if the measurements are right.

A floor plan does not necessarily need an architect. With a tape measure and a drawing app, or a phone with LiDAR, you can make a scaled drawing yourself — but the two methods give different accuracy, and an architect solves a different problem.

Yes. LiDAR is a shortcut, not a requirement — a scaled floor plan only needs real measurements and a fixed scale. Here are the four routes without a scanner.

Yes, but not the same way. Android has no built-in room scanner to match Apple's RoomPlan, and LiDAR only sits in iPhone Pro and iPad Pro. On Android, apps measure with the camera alone — it works, but it is far more sensitive to conditions.

Yes, with 2-5% uncertainty: calibrated steps, floorboards, tiles or a sheet of A4 paper give measurements good enough for a sketch — but not good enough to order anything against.

Yes, almost always — the load just has to be carried around it with a beam. That takes an engineer, calculations, and as a rule, planning permission, before work can start.

Yes — but each room has to be scanned on its own, and it's you who tells the app which floor the room belongs to. Basement, ground floor, first floor and attic aren't something the phone can see for itself.

Yes — but the wall behind the bookcase never gets measured, and that's where the error creeps in. Here's how much furniture shifts the numbers, and the four moves that save a furnished room.

"South-facing" covers anything from 158 to 202 degrees and says nothing about where the windows sit or what casts a shadow — check it yourself with a compass bearing and a shadow angle.

Yes, if the app has a built-in sample home. It is the only way to see what a finished floor plan, 3D model and takeoff actually contain before you spend time scanning your own place — and it is especially useful if your phone does not have the sensor scanning requires at all.

As a general rule, no — each has its own field in the property records and normally isn't included in the living area. But the boundaries are technical, and it's the local authority that decides how your room should be registered.

As a rule, yes, if the wall is load-bearing — because then you're changing the house's structure. A plain partition wall usually doesn't need one. The building authority makes the call.

Rarely. LiDAR saves you the measuring, not the floor plan itself — and a laser distance meter does the same job for a fraction of what a new Pro phone costs.

Edit the floor plan when you already know what's right. Rescan when you don't. Here is the short decision rule, and the five cases where a new scan is a waste of time.

As a general rule, yes — but it's the ceiling height the dormer creates that decides it, not the dormer itself. Here's the maths behind how many square metres a dormer actually adds.

Yes, but not because the air itself is expensive to heat. It is the extra exterior wall, the extra ventilation air, and the heat that pools above head height that costs.

Yes, a LiDAR scan can read the phone's compass and GPS along the way, and use them to set a north arrow on the drawing and find the home's approximate location. Both are weaker indoors than outdoors, and it is worth knowing why.

No — what HouseSense saves after a scan is a list of walls, doors, windows and furniture with measurements attached, not the video from the camera.

Only slightly — and far less than how you scan. Here is what the phone actually decides, and what is up to you.

The scan itself never needs internet — it happens on the phone. But many apps need a connection to save, process or export, and that is usually discovered in an empty basement with no signal.

No. The app writes a text you can take to whichever AI you choose yourself — there is no AI service the app sends anything to on its own.

Yes — scanning, the floor plan, areas and takeoffs are all calculated on the phone itself, and syncing to your iCloud simply waits until there's a connection again.

Yes — a LiDAR scan picks up the larger pieces of furniture and places them on the floor plan. If you draw the home yourself, you add the furniture afterwards. Either way, furniture never counts towards the area.

Exactly as accurate as your measurements — no more, no less. The drawing tool adds no error of its own; the tape measure, your memory, and the skipped intermediate steps do.

There is no single figure that holds for every room — accuracy depends on the room and on how you scan it. Here are the nine things that wreck it, and the one measurement that reveals whether your scan can be trusted.

With a tape measure and care, a wall measurement typically lands within ±0.5-1 cm; the errors come less often from the tape than from the sag, the skirting board and the reading angle. How small the deviation needs to be depends on what the measurement is for.

A standard 60 cm-wide fridge fits through almost any internal door — but a 90 cm-wide, 75 cm-deep American-style fridge needs a wide doorway, and often has its doors taken off.

The rule of thumb is a glazing area of at least 10 percent of the floor area — but it's the glass, not the wall opening, that counts, and the top of the window decides how far the light reaches in.

Look in the basement or the attic, check which way the floorboards run, or find the rows of nails in the ceiling. The direction is a clue about load-bearing — not an answer.

Split the room into rectangles and triangles, work out each part on its own, and add them up. Here are the three methods with numbers you can follow — and the check calculation that catches a mistake.

A semicircular bay window is half a circle. A shallower bay is measured in strips. Both can be worked out with a tape measure and a calculator — here are both methods, with numbers.

A room with a knee wall has several different areas — the floor you can walk on, the floor that is tall enough to count as living space, and the surface you have to paint. Here they are all worked out on the same room.

Planks, herringbone or tiles — and which way they run — is not just cosmetic. The direction affects how much wastage you get, how the room feels, and how much work goes into laying it.

Add the wall thickness times the house perimeter to your internal measurement. Here is the sum with real numbers, why it works, and how to take the two measurements it needs.

Deleting a home or a room in a measuring app is usually permanent. There is no undo button, and a drawing that isn't saved somewhere else is gone for good. Here is what to know before you tap delete.

A useful sun study needs five things: the address's position, the house's north direction, where the windows sit, what shades them from outside — and four dates to calculate.

One floor at a time, then stack them using two fixed anchor points: the staircase and one outer corner. Here is the method that keeps the floors lined up.

Split the room into rectangles, measure six figures instead of four — and let the sum of the parts prove the measurements are right.

Use the north arrow on the drawing, lay the plan over a map with north pointing up, or measure the facade's bearing with your phone's compass — and write the result down as a number of degrees, not as "south-west".

The short answer: you can gather clues yourself, but only a building surveyor or structural engineer can decide it. No app can answer this — not even HouseSense.

Use a detector, and read the wall from where the sockets, switches, radiators and taps sit — including on the other side of it.

Image AI can edit a real photo of your room to show new furniture, colours or style — but only if the photo is good enough, and the prompt is short and precise. When it goes wrong, it is usually one of three known mistakes.

An AI only accounts for children if you tell it there are children — and how old they are. Age, safety and everyday routines are not things a generic interior-design prompt thinks of on its own.

HouseSense can write the home out as a PDF, as a DXF drawing and as a 3D model in common formats other programs can read — so you are never locked in.

Furniture measurements hide in email receipts, brochures and memory — until you are standing in a new home trying to recall whether the sofa was 220 or 240 cm wide. A single furniture library fixes that by turning the measurements into something you look up, not something you guess.

The short answer: only the Pro models. Here are three ways to check — and what to do if the answer is no.

No app can look at a scan and decide whether a wall is load-bearing. But once you've found out yourself — from a surveyor, a structural engineer or an old set of drawings — you can mark it on your floor plan, so it's clear the next time you plan a renovation.

Measure the walls inside along the floor, then take the five measurements people forget: both diagonals, ceiling height in several places, the door's clear opening, the window opening with sill height, and wall thickness in each opening.

Measure the opening, not the glass: width, height, distance from the nearest corner, and the sill height from finished floor to the top of the window frame — the fourth measurement is the one people forget.

Split the room into triangles. Four wall measurements don't describe a quadrilateral uniquely — but three sides of a triangle do, so measure every wall plus at least one diagonal, and the room's true shape is locked.

Measure in a door or window reveal, face to face. If the wall has no opening, you can work out the thickness from two room measurements and one outside measurement.

In a basement it is rarely the ceiling that decides the height — it is the pipes, the ducts, and the floor that has not been laid yet. Measure both, and note the clear height under the lowest one.

You don't need to pay again when you switch phones. A subscription or purchase is tied to your Apple ID, not the physical phone — but it does require you to sign in with the same Apple ID and tap "restore purchases" in the new app.

If a seller, an estate agent or a friend has sent you a code for a home, you can usually pull the whole floor plan and 3D model onto your own phone. But you can rarely change anything — that kind of sharing is read-only for good reasons.

Measure the home, draw it as it is, then draw the change on top — and bring both drawings with measurements. That is what makes quotes comparable.

Five minutes of preparation removes most of the errors a scan can make in the first place. Here is the checklist — and the order to walk the home in.

Print the PDF at 100 percent or actual size — never fit to page — then check it afterwards with a ruler on a measurement you already know.

You revoke the share code inside HouseSense — and the recipient loses access immediately, both on the web and in the app.

Hold the phone at chest height, walk slowly along the walls the same way round, and finish where you started. Those are the three things that decide whether the scan turns out usable.

Send a PDF to whoever needs to read the drawing, and a DXF to whoever needs to keep drawing on it — and write the scale, date and where the measurements came from directly on the drawing.

Send a PDF if the recipient just needs to see it; send a link or a code if the home needs to open in a browser without an app — and put an expiry date on it when it is a stranger.

Draw the room large and deliberately out of scale, letter the corners, and write each measurement directly on the line it belongs to — the sketch needs the right number of walls and openings, not the right proportions.

A chat AI can suggest furniture, colours and layout if you tell it what the room actually contains — measurements, windows, your own furniture and who lives there. Without those numbers, it is just guessing at a room that isn't yours.

Split the room into three kinds of surface: vertical walls, sloped ceilings, and the flat ceiling panel between the collar ties. The sloped ceiling's area is its actual length along the slope times the room's length — not the horizontal projection.

There is a minimum height before the floor under a sloped ceiling counts as living area — in most local rules, somewhere around 1.5 m of clear height to the ceiling. Here is how to measure the line yourself and work out the area.

The home itself you can measure and judge from a drawing. The neighbourhood calls for something else: distance to road and railway, how close the neighbour sits, what you can see from the windows, and how far it is to school and shops. Most of those figures can be found on a map before you ever stand there.

Measure two rooms separately and add their areas together, and you've typically counted the wall between them twice — once from each room. The error is small per wall, but grows with the number of rooms, and it's easy to avoid once you know where it comes from.

A renovation budget only becomes something you can trust once it is built on measured areas instead of a guess. Here is the method: measure first, set prices per square metre afterwards, and add a buffer on top.

By removing the differences that have nothing to do with the homes themselves: the weather, the time of day, the furnishing, and how fresh the memory is. Compare the same five figures, not two moods a week apart.

Draw the knee wall as a real wall, write two heights on every room, and add a dashed line where the ceiling is high enough to stand up straight. Then the drawing stops promising more than the floor can deliver.

Most drawing apps let you do both: drag a room out roughly with your finger and correct the precise measurements afterwards, or type the figures in directly from the start. The first method is fastest to get going with. The second is fastest once you've already measured the whole home.

An opening on a floor plan isn't just a gap in a line. It has a width, a position along the wall and — for a window — a sill height, and all three figures need to be there if the drawing is going to be any use.

Divide the room up by height instead of by floor space: the low pieces at the outer edge, the tall pieces towards the centre, and storage built in to follow the slope of the ceiling. Here are the measurements that decide what can stand where.

The first fifteen minutes decide whether the rest goes smoothly. Clear the room, grant the app the access it asks for, and let your first attempt be a test room, not the hardest room in the house.

Five rooms, five lists and a fridge covered in receipts is the classic recipe for buying the same thing twice — or forgetting it entirely. One combined list with a status per item solves it.

By giving every home its own fixed slot — the same fields, in the same order — instead of scattering your notes across text messages, email threads and memory. A house hunt spread over several weeks typically grows to five or ten candidates, and at some point nobody can hold them all in their head at once.

Use the tape's hook against a corner or the skirting board, measure from a point inside the room out to both ends, split long walls into stages with a fixed midpoint — or use a laser distance meter, which never needs a second person.

Measure six things: the staircase's narrowest clear width, the clear height straight up from the step nosing, the landing's two measurements, the staircase's pitch and what protrudes into it — it's the clear height, not the width, that stops the furniture.

Split the room into triangles, measure every side and every diagonal, and work out the area with Heron's formula — that gives you the true area, even when no angle is 90 degrees.

Measure from finished floor to finished ceiling in at least four places in the room. The number a tradesperson needs is not the average — it is the difference between the lowest and the highest reading.

A room with a sloped ceiling doesn't have one ceiling height, it has a curve. Take three measurements — at the knee wall, at the highest point, and the horizontal distance between them — and you can work out everything else.

A floor plan is the home seen from above, sliced through at about 1.2 metres. The black lines are walls, the gaps are doors and windows, the arc shows which way the door opens — and the scale translates the paper into reality.

The quarter-circle arc by the door is the answer: it starts at the hinge side and sits in the room the door swings into. Here is the full reading — and why it decides whether the bed can go there.

By recording the same five or six things in the same order in every home, and writing it down within two minutes of walking out the door. Memory can no longer keep homes apart after the third viewing.

Scan the rooms one at a time and you typically end up with separate islands that can't be merged into a single floor plan. The fix is to walk through everything in one continuous tour, where the phone never loses track between two rooms.

A 3D model of a multi-storey home is hard to show as one continuous space — the stairs connect two floors that are rarely scanned or drawn as one. Most apps solve it with a teleport point instead of a real staircase you can walk up.

Flooring, tiles and skirting are sold in fixed pack sizes, not by the loose metre. Here is how to round correctly from square metres to packs, and how much waste to add on top, depending on the pattern.

Under a sloped ceiling there isn't one ceiling height — it changes with every centimetre towards the ridge. Measure three numbers — knee wall, ridge and width — and you can work out the height anywhere.

Two questions you run into right away when you open a floor plan on a phone or tablet: how do I zoom in on a room, and can I rotate the drawing so north points up? The answer is the same gestures you know from maps — with a couple of pitfalls.

Your body changes its mind at around 2.00 m — below that, you start to duck. A room with a sloped ceiling feels like a room once at least half the floor has more than 2.00 m of headroom, and the tall zone is at least two metres wide.

Over a dining table a pendant typically hangs 60-70 cm above the tabletop, whatever the ceiling height. Ceiling height doesn't decide the hanging height — it decides the length of the cord.

A sharing code for a home usually isn't permanent — it has an expiry date, much like a link to a video or a document. Here's what that means in practice, and what to do once the code has run out.

Budget around an hour per floor for measuring and 20-40 minutes to enter it into the app — and expect it to halve the second time you do it.

A professional typically lays 20-40 m² of click flooring a day; laying it yourself for the first time, plan on 8-15 m² a day — plus 48 hours of acclimatising the flooring beforehand.

At the winter solstice the sun's midday height is 90° minus your latitude minus 23.4° — around 15° in London, 11° in Copenhagen and Edinburgh, 25° in New York. Low enough that everything casts a shadow several times its own height.

Multiply the floor area by the ceiling height. A room of 15 m² with a 2.5 m ceiling holds 37.5 cubic metres of air — and under a sloped ceiling you use the average height instead.

Sun hours in a room depend on three things working together: which way the window faces, how large the window is relative to the floor, and what stands in the way outside. Most people can estimate it themselves with a compass and a couple of rules of thumb.

Take the room's internal perimeter, subtract the door openings, and add 10% for mitres and off-cuts — then round up to whole lengths in whatever size the shop sells.

Measure the patio area, add 5-10% wastage for square, straight-laid surfaces and 10-15% for irregular edges or a diagonal pattern — and remember a fall away from the house of 1-2 cm per metre.

Buy the floor area plus wastage: 5-10% for ordinary straight laying, 10-15% for diagonal and 15-20% for herringbone — and always round up to whole packs.

Work out the floor area plus the wall area (perimeter × tile height), add 10% wastage for a straight lay and 15% for a diagonal one, then round up to whole boxes.

Divide 1 m² by the tile's area including the grout joint: a 30 × 60 cm tile with a 3 mm joint takes up 0.1827 m², so 5.5 tiles fit a square metre.

Two viewings is the norm: one for the overall impression, one to test it with measurements, questions and a different time of day. A third visit only makes sense if you have a specific question it can answer.

Roughly twice as much as you think — an area error is about twice the length error, in percent. Here is the calculation you can do yourself in two minutes.

Diagonal laying costs 10-15% wastage and herringbone 15-20%, against 5-10% for straight laying — on 30 m² that's 3-4 m², or roughly two extra packs.

Filler is calculated in kilograms per square metre per millimetre of layer thickness — not in square metres per tub. Here are the figures, worked through for a whole room.

A wardrobe doesn't just need to be shorter than the ceiling — it needs room to be tipped upright. The wardrobe's diagonal is longer than its height, and it's the diagonal that decides whether it fits.

There is no single figure that fits every room. A kitchen, where you chop vegetables, needs more light than a living room, where you relax — and both need more light sources than just one ceiling light if the lighting is to work in the evening.

Wallpaper is counted in drops, not square metres — which is why a roll goes shorter than the area suggests. Lining paper is counted in square metres plus a bit over ten percent for trimming.

A home has roughly twice its floor area in wall area. An 80 sq m flat typically needs 40-55 litres of wall paint, 14-20 litres of ceiling paint and 8-11 litres of wood paint.

Work out the net wall area — the wall area minus doors and windows — multiply by two coats, and divide by the coverage. Here is the sum spelled out on a real room.

A flat ceiling has exactly the same area as the floor. Multiply by two coats, divide by 7-10 m² per litre — and add extra if the ceiling slopes.

The house's perimeter times the wall height, plus the gable triangles, minus windows and doors. Exterior paint only stretches 4-6 sq m per litre — masonry drinks far more than an interior wall.

A standard interior door with its frame is roughly 5 sq m of painted surface on both sides. Two coats typically use 1-1.5 litres of wood paint.

Reckon on at least 75-80 cm from the table edge to the wall just to sit down, 100 cm if someone needs to walk behind a seated guest, and 120 cm if there's a cabinet on that wall too.

The sun's position can be calculated precisely from address, date and time — what you have to measure yourself is the house's north direction, where the windows sit, and how high the neighbours and trees stand.

Allow 3-5 kg of tile adhesive per m² with a 6 mm notched trowel and 5-8 kg with a 10 mm — and 0.2-1.2 kg of grout per m² depending on tile size and joint width.

A door is never as wide as its name suggests: the name is the door leaf measurement, and the opening you can actually carry a piece of furniture through is a few centimetres narrower. Here are the four measurements of a door, and how to work out the right one.

A doorless opening between two rooms should be at least 90 cm wide. 120-160 cm gives a genuinely open connection, and beyond 3 m it will usually need a structural beam.

A hallway needs to be at least 90 cm wide to work, 110-120 cm if two people need to pass each other — and the width is measured between whatever is actually in the way, not between the walls.

A scan measures the geometry; a drawing has the geometry you type in yourself. Afterwards, the two are almost impossible to tell apart inside an app — but "almost" is a word that matters once the numbers are used for something that actually costs money.

The difference is who can get to your data if something goes wrong — in your own iCloud the developer cannot read it, but on the other hand nobody else has a copy either.

In a home with several rooms: yes, and the gap grows with the number of rooms. A scan takes the time it takes to walk slowly along the walls — a manual takeoff needs a number for every single thing you want to know.

Usually yes — but check first whether the estate agent already includes it in the marketing package, and whether a usable drawing already exists in the local planning archive. Often the extra purchase turns out to be unnecessary.

Morning sun gives a cool house and light early in the day; evening sun gives sun at the hour most people are actually home — but costs the house its warmest afternoon.

Trust the tape measure you hold in your own hand, at the right spot. Here are the five reasons a scan and a drawing of the same room don't agree — and how to work out who's right.

The first choice is not which app or which tape measure — it is whether you can scan or have to draw. That is decided by the phone in your pocket, not by what you would prefer. The rest of the task falls into place once that is settled.

Yes — a floor plan with measurements gives an AI an overview a single photo cannot: the whole shape of the room, every wall and opening at once, seen from above. It is not a requirement, but it is often the fastest route to a suggestion that actually fits.

A laser measures a single dimension far more accurately than a phone. A phone measures an entire room at once. The two don't solve the same problem — and most people benefit from both.

It's optional, but the address solves several small problems at once: it keeps track of which house is which, it gives a map lookup somewhere to start, and it makes a shared floor plan meaningful to a recipient who has never seen the home themselves.

To the wall surface. Measure to the centreline instead, and the two rooms each count half of the shared wall — and the house ends up looking bigger on paper than it really is.

Always prime new, absorbent, stained or glossy surfaces. Primer covers 8-12 m² per litre and typically saves a whole coat of expensive topcoat.

Most home apps offer both routes: look the address up, or let the phone find the point with GPS. They don't always give the same result, and one of them only works in exactly one place — wherever you happen to be standing.

Laser for long, straight measurements between two surfaces — walls, ceiling heights, room lengths. Tape measure for anything without a surface to aim at: openings, diagonals, furniture dimensions and wall thicknesses. Bring both.

Lay the floor under the whole kitchen if it is tiled or glued down — and only up to the front edge of the cabinets if it is a floating click floor.

Reflections, mirrors and furniture close to a wall can trick a 3D scan into drawing surfaces that aren't really there. The fix is rarely to scan again — it's to remove the wrong surface from the drawing afterwards.

When you share a home from a measuring app, it is not your whole account that opens up to the recipient. It is a defined package: plan, measurements and a 3D model. Photos and private notes usually stay home.

Four dates a year mark the sun's extremes and turning points. Know them, and you can compare how light falls in your home at the year's two opposite poles, instead of guessing from a single sunny afternoon.

A linear metre is length alone — no width, no height. Skirting boards, worktops and new partition walls are priced per metre, because the work follows the length, not the surface. So your takeoff needs both square metres and linear metres.

The Measure app is a digital tape measure and a spirit level: it measures distances, heights and rectangles. It cannot create a floor plan, calculate square metres, or save a room.

Go against the flow, use the empty rooms while everyone else is in the kitchen, and settle for three or four measurements plus sound, light and the flow between rooms. A thorough takeoff belongs at a private viewing — ask for one.

Prioritise what you can't work out from home afterwards: ceiling height, clear passage widths, the rooms' real shape, window sill height, and where radiators and soil pipes sit. Floor area, build year and energy rating are already in the listing.

The eaves space is the low void behind the knee wall on a first floor. It is excellent for storage on pull-out units, but it does not count as living area — and it must not be sealed up if the roof is ventilated through it.

LiDAR doesn't see through curtains, blinds or closed shutters — it measures whatever surface it hits first. If a window is covered when you scan, it can simply be absent from the drawing, and the fix is to add it back in by hand afterwards.

First: check whether the difference is simply the walls. Most "wrong record" cases turn out to be two different ways of measuring. If something is still left over afterwards, it's the owner's job to get it corrected — through whichever authority keeps the record.

Measure it with a tape and draw it in. Here are the seven rooms that most often trip up a LiDAR scan — and exactly which measurements to bring home from each one.

Mirrors send the scan into a room that does not exist, and clear glass disappears entirely. Here is why it happens, how to spot it in the drawing, and the four fixes that solve it.

Design and engineering fees for an ordinary extension typically land around 5-10% of the construction cost — more on a small extension, where the fixed costs weigh heaviest. Here are the four line items that percentage is made of.

A floor plan is full of lines that do not look like what they represent — a door is an arc, not a rectangle, and a thick line means something different from a thin one. Once you know the symbols, you can read a plan in a minute.

Built-up area is the house's footprint on the plot, seen from directly above. If the house has two storeys, it is roughly half the living area — and that is not a mistake.

1:50 means 1 cm on paper is 50 cm in reality. 1:100 means 1 cm is 1 metre. Here are the sums, the fixed scales used in construction, and why a printed PDF rarely holds its scale.

There is no single price, because there is no single product. Four different things get sold under the same name, and they sit at four different price levels — and the most expensive line is often the one nobody mentions: the survey.

The buyer sees the floor plan, the measurements, the areas and the 3D model in an ordinary browser — but never your photos and never your notes.

A land surveyor works on the plot, not the rooms. Fees vary hugely between markets, so the real question isn't the price — it's whether the job belongs with a surveyor at all.

A neighbouring house to the south steals winter sun first and summer sun last — settle it with one angle: arctan(height divided by distance), weighed against the sun's height on the date.

Piers between windows, alcoves, chimney breasts, crooked walls, and doors sitting somewhere other than you remember. A scan has no expectation of what a room ought to look like — and that is its biggest advantage over your own drawing.

The registered area is the basis for the listing, the price per square metre, and the buyer's comparison. If it is wrong, it is usually discovered late — and it is more expensive to correct mid-sale than before.

From nothing to a subscription. The important part isn't the price, it's what's free: almost every app lets you scan freely and only charges once the drawing has to leave the app.

Often nothing at all — the drawings for a block of flats usually already exist with the owners' association or in the planning archive. Check four places before you pay anyone to measure up.

From nothing at all to a serious professional fee — and what decides the price isn't how neat the drawing looks, but how much liability comes attached to it.

A drawing set from a design office typically costs a modest fee — but for a small structure you can often draw what the authority needs yourself. The expensive part is rarely the drawing; it's the boundary.

An ordinary click floor fitted by a flooring contractor is one of the cheaper jobs in a home — but it is not the floor itself that decides the bill. It is what lies underneath it.

Materials for an ordinary room add up to a modest shopping list, and most of it is paint you can work out in advance. Get a decorator to do the work and the bill is typically three to five times as much — nearly the whole difference is hours, not paint.

The price depends entirely on what is sitting above the ceiling. Taking down a suspended ceiling is small change; opening a loft up to the ridge is a renovation with an engineer, insulation and a new ceiling surface. Here is how to work out which of the three jobs you actually have.

One question moves the price more than anything else: does the wall carry any load? A light partition is a manageable job. A load-bearing wall is sometimes several times more expensive — it's the beam and the engineer that move the figure.

A tape measure, an hour per floor, and a fixed routine. Here is exactly which measurements to take, in what order — and what you can skip.

The north arrow shows which way the home actually faces. Without it you cannot tell which rooms get morning sun, evening sun or no direct sun at all — and you must never assume that north is up.

The architect needs a DXF in metres to draw on top of, a PDF of the same drawing as a reference — and a line about how the measurements were taken.

Three kinds: the drawing (PDF and DXF), the model (OBJ, STL, PLY, glTF, GLB, DAE, USDZ), and the raw measurement points (PLY, XYZ, PTS, LAS) — and the choice depends only on who has to open it.

The short answer depends on the app, but a well-designed app never deletes your data just because a subscription expires. The key difference is between "read-only" and "deleted" — and it's a difference you should know before you say yes to a subscription, not after.

Delete HouseSense and the local copy on your phone is gone, but the homes in your own private iCloud remain — reinstall the app with the same Apple ID and they come back.

Scandinavian, japandi, boho, industrial, midcentury — the words get used a lot without explanation. Here are the most common styles, what defines each of them, and how to find the one that fits you.

Apple's room scanner RoomPlan arrived with iOS 16 in 2022, and the ability to stitch several rooms into one building came the following year. If you're running the latest iOS, you're covered.

The clear opening is the smallest width and height an object can pass through with the door fully open — measured between the inner faces of the frame and from the finished floor to the underside of the frame, not off the door leaf.

DXF is Autodesk's open exchange format for drawings, and it is read by AutoCAD, Revit, ArchiCAD and SketchUp; DWG is Autodesk's closed format, which only their own and licensed programs can write.

A half-height wall (also called a pony wall) doesn't reach the ceiling — typically 90-120 cm tall. It divides a room visually without shutting out light and air.

A level is a height measured against a shared zero point — either mean sea level or a home's own ground-floor slab. The numbers next to floors, ground and ridge tell you what sits highest, and by how much.

A point cloud is the raw measurement points from a scan: millions of individual measurements with x, y, z and a colour, with no interpretation of what is a wall and what is a sofa.

The ridge is the highest line of the roof — where the two roof planes meet. That one simple detail decides how much usable space there is under a sloped ceiling, and why two rooms with the same floor area can feel entirely different to live in.

A section is the house cut straight down and seen from the side. It shows ceiling heights, floor build-ups, roof pitch and the guts of the construction — everything a floor plan and a facade elevation cannot show.

There is no single number. Ceiling height varies with a home's age, floor and renovation history — and the only figure that applies to your home is the one you measure yourself, in several spots in the room.

A takeoff report is a document listing a home's measured areas room by room, stating who measured them and by which principle. It is used whenever area matters in a sale, for contractor quotes, and for ordering materials.

A trimmer (or lintel-and-trimmer) is the beam that carries what a removed wall used to carry. The cost follows the span — and the bearings at each end often cost more than the beam itself.

A window and door schedule is a list of every window and door in a home, with its measurements and location — the document a tradesperson or supplier asks for when they need to give a quote without visiting in person.

The straight line on a property map lies. A school 600 m away as the crow flies can easily be 1.1 km when you have to walk the actual streets. Here is how to check the real walking distance — and what to look for along the way.

An elevation is a wall seen straight on, with no perspective. It shows heights — window height, sill height, ceiling height, sloped ceilings — that a floor plan simply cannot show, because a plan is only ever seen from above.

An estimated ceiling area is a calculated figure, not a measured one — especially true in rooms with a sloped ceiling, where the surface can never be scanned or measured directly. Here is how the figure comes about, why it is often larger than you think, and what you can and can't use it for.

Extra work is everything that wasn't in the quote. It happens either because the quantities were wrong, or because something unexpected turned up. You can remove the first kind entirely by measuring properly; the second you can only agree your way around in advance.

RoomPlan is Apple's built-in room scanner for developers: it uses LiDAR and machine learning to recognise walls, doors, windows and furniture as you walk around a room. It is not an app you can download — it is the engine under many of them.

Sill height is the distance from the floor up to the underside of the window frame. It decides how much you can see out, how much light reaches the lower part of the room, and whether the window can serve as an escape opening or have furniture placed in front of it.

A 3D scanner creates a model of the surfaces as they look. A floor plan app creates a drawing of the building as it is built — with walls, doors and measurements. They look alike on screen and can be used for very different things.

A fixed-price quote is a firm price the contractor is bound by. An estimate is a qualified guess that may shift. Time-and-materials work is hours and materials, billed as they fall. Which model you are offered depends on how good the measurements you hand over are.

Floor area is length times width. Wall area is the room's perimeter times the ceiling height, minus doors and windows — and it is typically more than double the floor area.

LiDAR measures distance directly, with light. Camera-based methods compute distance from images. Draw it yourself, and the measurements come from your tape measure. The three methods fail in different places — here is where.

OBJ is read by almost everything, STL is for 3D printing without colour, GLB is one self-contained file for the web and Blender, and USDZ opens directly on iPhone, iPad and Mac.

Most floor plan and scanning apps have a free version and a paid one. The line is rarely drawn where you would expect — it is usually not the features that get locked, but the number of homes and the ability to share with others.

USDZ is Apple's format for 3D models that open straight in the camera — no app installed. Send a USDZ file to an iPhone or iPad user and they can place your home model right in the middle of their own living-room floor. For Android and Windows you need a different format.

The painter works in net wall area, ceiling area and number of coats. The flooring fitter works in floor area plus waste and running metres of skirting. The carpenter works in running metres and item counts. Here is what each trade needs — and what each of them cannot use.

Living room, kitchen, bedroom, bathroom, hallway — most floor plans sort rooms into a fixed set of categories. It is not just decoration: the room type drives the icon on the drawing, and in many apps also what the room is suggested to be called if you do not name it yourself.

A good home screen answers two questions at once: what does the home look like, and how far along are you with it. Everything else — buttons for the individual features — can wait for the next tap. Most apps mix it all together and show too much at once.

Quantities, not rooms. A usable request for quotation contains measured areas, a list of openings, the condition of the surfaces, access conditions, the desired timing and a reply deadline — that is what makes the quotes comparable.

A technical prompt describes the room as numbers, not mood: where each wall starts and ends, where the windows and doors sit, and which furniture is already in place. It is the type of prompt that produces the fewest guesses and the most usable answers.

A measured floor plan, the takeoff for each room, a list of doors and windows, photos of the surfaces, your questions written down — and something to take minutes on. The meeting usually lasts under an hour; the preparation decides what that hour is worth.

Ten points: the quantities, the scope, what is excluded, tax, materials, the schedule, payment, extra work, validity and the company's registration. If the quantities are missing, it isn't a quote — it's just a number.

Check four things before you download: can you correct the measurements afterwards, can you get the file back out, where does your data live, and what does it cost once the trial ends.

Every wall's internal length, at least one diagonal per room, ceiling height at several points, every door and window with the opening's size and its distance from the nearest corner, wall thickness, and which room lies on the other side of each wall.

Ask about what isn't in the paperwork: when was the home renovated and with what drawings, why the official area and the listing's area don't match, what has been replaced and when, and how long the home has been on the market. And ask permission to measure and scan before you do it.

A charged phone, a tape measure at least 5 metres long, a written list of no more than ten points, and the measurements of your three biggest pieces of furniture. Everything else is optional — and a laser distance meter is the best of the optional extras.

The second viewing is for what you could not get to, or did not dare ask, the first time: measurements, technical details, the flow between rooms, and the light at a different time of day. Bring a written list — otherwise you spend half an hour falling in love all over again.

The wall behind the photographer, the ceiling height, how the rooms actually connect, sound and smell, and what is fixed to the walls: radiators, pipe boxing and the fuse board. Listing photos are shot from corners with a wide-angle lens, and they systematically show the tidy half of the room.

Keep the scan inside what is actually yours to measure — a neighbour's garden, shared basement corridors and other people's rooms are not part of your survey.

Most move-in mistakes are not discovered in the chaos of moving day, but weeks later — when the heating bill arrives, or a fault turns up that no one can remember was there before. A room-by-room checklist catches it while you can still do something about it.

Not just one area figure for the whole home — but measurements, budget, a to-do list and photos for every room on its own. Most decisions are made at room level: what does it cost to paint this room, will the bed fit in this bedroom. A single total for the whole home answers neither question.

The official property record is the property's registered profile. Here are the fields that get misread most often, and how to read them without drawing the wrong conclusion.

An external wall faces the outdoors and has to keep out weather, cold and damp. A partition wall stands inside the home and divides rooms. Thickness is usually the quickest giveaway.

An estate agent floor plan is meant to sell a layout, and nobody stands behind its measurements. A construction drawing has to be buildable and approvable, with real dimensions, scale, wall thicknesses and a named professional behind it.

Gross area is measured around the outside of the exterior walls, living area is the inhabited part of that, and net area is the actual floor inside the rooms. Here are all three worked out for the same house.

A scan measures the home as it stands. A drawing reproduces the home as you understood it. Both can produce a measured floor plan — the difference is who decides what's there.

The rule of thumb: if the drawing is used to decide something, you can make it yourself. If it is used to approve something or commit someone to a price, a professional needs to be behind it.

The answer depends on three things: which way the room faces, the season, and what is blocking the view outside. Here is how to work it out yourself — and how an app can show it to you instead.

No. Solar noon falls around 12:00 on standard time and around 13:00 once the clocks go forward for summer time — plus a correction for how far your longitude sits from your time zone's meridian, and up to a quarter of an hour for the time of year.

Scan when you are standing in the home and pressed for time. Draw when you are not there, or when you want to draw something that is not built yet. Here is the answer for nine concrete situations.

Start with the local authority's building case archive — it is usually free, and most authorities have put the archive online. After that: the old estate listing, the ownership-transfer documents, the kit-home manufacturer, and the previous owner.

You have asked an AI to visualise a new interior and got an image back. The question is where that image should live so you can find it again — and whether you can collect several proposals for the same room without mixing them up with each other or with your ordinary photos.

HouseSense stores scans, floor plans and figures on your own iPhone and in your own private iCloud — there is no account, no server on our end and no tracking.

Put the patio south if you want to use it early in the year, and west if you want to use it in the evening — and keep it clear of the house's own shadow, which at midwinter is many times the height of the house.

There are four kinds: Apple's built-in Measure app, LiDAR scanners, camera-based apps without LiDAR, and drawing apps where you type in the measurements yourself. Here is the difference, and what each type can and cannot do.

On the home floor area, not the plot, not the basement, and not the sum of the rooms floors. Mix up two different areas, and the same home can look 45% cheaper without the price changing at all.

The main rule: lay the boards along the room's longest dimension and parallel to the light from the main window — but the subfloor can override both.

Keep a PDF of the floor plan, a DXF of the same drawing, your photos — and the point cloud, if you have one: the four cover what you need to show, what others need to work in, and the evidence of what you actually measured.

Five figures decide it: net wall area, floor area, ceiling area, the size and position of every opening, and the ceiling height. Known, and a fixed price can be worked out — miss one, and it becomes an estimate.

Eight measurements no scan is the right tool for — and together they take under ten minutes to take yourself.

Camera to scan rooms, and location for the north arrow and the sun calculation — the app does not ask for contacts, microphone or tracking.

If you need to place the bedroom, the dining table or the home office correctly, it's not enough to know the home "faces well". You need to know which room actually gets sun early, and which one only brightens up late in the day — and that depends on compass direction, not gut feeling.

Pick the compass direction by when in the day you use the living room: south gives the most hours and the best winter sun, west gives evening sun and the biggest risk of overheating, east gives morning light and a cool evening.

Some cracks are normal settling in plaster and joints. Others are a sign the structure is moving — and those need an engineer to look at them right away.

Usually because the three contractors have actually priced three different jobs. The difference lies in quantities, scope and caveats — not in the hourly rate. A shared set of measurements and a shared job description removes most of the spread.

Because most features in a home app calculate from numbers the app can't invent on its own — a budget needs an area to multiply, a 3D model needs a geometry to build from. Without data to build on, a feature isn't locked by the business; it's empty, because there's nothing to show yet.

A "what's new" screen isn't an advert — it's the shortest route to discovering a feature that solves something you've already been fighting. Here's how to tell a good changelog from an annoying one.

Small projections and recesses disappear because a scan has to decide what is a wall and what is furniture — and because the phone never got close enough. Here is why, and how to capture them.

Because the public building register, the surveyor, the estate agent, the tradesperson and your own tape measure are each answering a different question. Here is what each figure means, and when to use which.

You measure a window from inside the room, step outside and measure again — and the figures don't match. That is not a mistake. A window opening has several widths, depending on where along the opening you put the tape.

A floor plan you draw yourself looks at the room from above — like a bird. It cannot see how high the ceiling is, because it simply isn't looking that way. That figure is one you have to supply.

A camera doesn't see the way the eye sees. How much of a room fits into the frame — the field of view, FOV for short — decides whether a room feels spacious or cramped. Property listings usually lean on one extreme, a poor app view the other.

Two windows that look identical in real life can easily end up with different measurements on a surveyed floor plan. It is rarely the windows that differ — it is the measuring itself.

Scan several rooms in one go, and the app may register them as one connected group instead of two separate rooms. That is not a bug — it is how the scanner remembers that the rooms sat in sequence. But it can be undone.

Because a scan measures what the phone could actually see that day — not a lookup of a fixed answer. Here are the five reasons the same room ends up with two different measurements, and how to decide which scan to trust.

Because construction drawings measure in millimetres without a unit, as a rule. It removes decimal points, which can vanish in a photocopy, and makes every figure on the drawing directly comparable.

A floor plan can be drawn without knowing where the house is. But as soon as the app needs to calculate sunlight, shadows from neighbours or noise from a road, it needs to know two things: the position, and which way the house faces. That is not the same question.

The windows haven't changed, but the daylight has: the day is under seven hours long, the sun sits around 11 degrees high, and an overcast winter sky delivers a fraction of summer's brightness.

Because uncertainty costs money, no matter who carries it. Either a safety margin gets built into the fixed price, or you end up paying the overrun afterwards. Measured quantities remove the reason for the margin in the first place.

Ceiling height multiplies a room's area into a volume — and it decides how far daylight can reach in. 20 cm of extra ceiling height in a 25 m² living room is 5 cubic metres more air.

Reverberation grows directly with the room's volume in cubic metres. A high ceiling adds volume without adding soft material — that is why it echoes, and why the fix is surfaces, not height.

Because the phone is constantly working out its own position from the position before it — and each small error stacks on top of the next. Here is what drift is, where you see it, and how to keep it down.

When a home has been scanned in several sessions — an extension on its own, a floor on its own — the two parts can land wrongly relative to each other on the drawing. That is not a fault in the scan, but in the stitching, and most apps let you correct it by hand.

A south-facing room is rarely overheated by the south window alone — it's the roof windows, west-facing glass, missing external shading and a 17-hour summer day that do the damage.

Because the eye measures a room by comparing it to objects whose size it already knows. Without furniture, that yardstick is gone, and the brain guesses low — while a furnished room with deliberately undersized furniture makes it guess high.

Measure vertically from finished floor to ceiling at three points: two opposite corners and the middle of the longest wall. Floors settle and old joists sag, so one reading taken in the centre of the room is rarely the room's real height.

A floor plan you understand perfectly yourself can be completely misread by a tradesperson reading it in their second language. Language in a home app is not about convenience — it is about who actually has to use the drawing afterwards.

It's a snap feature — a shortcut that straightens the furniture parallel to the wall and pulls it in close when you drag it nearby. It exists because most furniture ends up there anyway, but it can be turned off.

A scanned floor plan often follows whatever angle the house happened to be scanned at. It looks messy, but it is rarely a measuring error — and most apps can straighten the drawing without changing a single dimension.

The figure on the tin is a theoretical coverage measured under ideal conditions. In a real room paint typically goes 20-40 percent less far — here are the six reasons.

A 3D model of a whole home can contain tens of thousands of triangles, shadows recalculated every frame, and light hitting every surface in real time. That is heavy work for a phone, and there are concrete things that make it heavier or lighter.

A floor plan shows the floor from above and says nothing about height. On a first floor with sloped ceilings, a third of that floor is often too low to stand on or put furniture against — and you cannot see that on the drawing.

Because a listing often adds areas together differently than the public property record does — and because the registered figure can simply be out of date. Here are the five explanations, in the order you should check them.

The public property record counts registered habitable rooms — not the rooms a family actually uses as bedrooms and living space. Kitchens and bathrooms usually don't count, and a room created by splitting another one won't appear until it has been reported.

A 3D scan recognises openings from shape and position, not from function. A low-set window, a French door or a floor-to-ceiling window can easily end up in the wrong category — and it is simple to fix once you notice it.

Because the tradesperson cannot vouch for your measurements, and because the visit is about more than numbers: substrate, access, unevenness and everything a tape measure never catches. Your measurements make the visit shorter — they rarely make it unnecessary.

Because the drawing usually shows the house as it was planned, with internal dimensions — while the registered area is measured externally. And because houses are rarely built exactly as drawn.

Because a scan has to decide where the floor and the ceiling begin — and rugs, glossy floors, cornices and lamps shift that decision. Here are the six reasons and the check.

Because official areas are usually measured from the outside, to the outer face of the exterior walls, while you measure from the inside, wall to wall. The difference is the walls themselves, and it is bigger than most people think.

Because each room is measured on its own and has to be pieced together afterwards. When the piecing-together fails, the drawing must not guess at the placement — so the rooms sit in a row until you set them in place yourself.

Because the room isn't square. A LiDAR scan measures the walls exactly as they stand — and real walls are crooked, curved and unevenly plastered. Here is what that unevenness is made of, and when you should straighten it out.

Because a floor plan is a straight view from above: a piece of furniture is shown as the floor area it occupies. The rectangle isn't a simplification of the furniture — it's its real footprint, and that's exactly what you need when furnishing the room.

Because the geometry made the trip but the appearance didn't: OBJ keeps colour in a separate MTL file, and STL can't carry colour at all.

Because the registered area of a flat is, as a rule, a gross area: walls and often a share of the stairwell and corridors count towards it. Your floor is always smaller.

A measured wall that is actually straight rarely comes out as a perfectly straight line. Here is why measuring noise skews walls on the drawing, when it is worth correcting, and what it does to the floor area.

Your phone's compass uses the earth's magnetic field — and indoors, that field is full of noise from reinforcing steel, door frames, fridges and wiring. A compass can be off by 20-30 degrees just a few metres from where it was fine in the garden.

Because the house's area is measured around the outside of the external walls, while the rooms are measured inside them. Walls typically take up 15-20% — here's the arithmetic for a 120 m² house.

A true sun calculation needs three things: where the house sits on the globe, what time of year and day it is, and which way the building faces. Miss just one of the three, and no app can show you the real sun — only a neat guessed arc.

Because flooring is produced in batches with different colouring — in two years you may not be able to buy the same floor again, and then three damaged boards can mean a whole new floor.

A floor plan's fixed words, such as "Kitchen" or "Width", can be pre-translated by a program. But if you type your own name into a room, such as "Dad's Study" or "Utility Room", that is an entirely different task to translate, and most apps cannot do it.

Allow 70 cm of clear floor along each side of the bed and 70 cm at the foot end: a 180 × 200 cm double bed therefore needs a bedroom at least 3.20 × 2.70 m.

The sofa will fit through the door if its smallest dimension is less than the door's clear opening — but it can only turn a corner once the hallway is clearly wider than the sofa's depth.

Headroom under a sloped ceiling grows with the distance from the knee wall: a 200 cm wardrobe needs 110 cm of clearance at a 45° roof pitch — but a full 191 cm at 30°.

A standard washing machine is 60 cm wide, 55-65 cm deep and 85 cm tall, and it clears most internal doors — but the recess needs to be 8-10 cm deeper than the machine, because hoses and taps take up space behind it.