When is it best to scan a home, and when is it best to draw it?
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.
Short answer: Scan when you are physically in the home, have an iPhone or iPad with LiDAR, and can walk along the walls — it is the only method that finds the niches and irregularities you would not spot yourself. Draw when you are not in the home, when the phone has no LiDAR, when the room is inaccessible, or when you want to draw a renovation that does not exist yet. When in doubt: scan first, and correct it on the drawing board afterwards.
Situation 1: Open house, and you have a quarter of an hour
Scan. This is the scanner's strongest case. You probably will not come back, you do not have time to measure 30 numbers with a tape, and you do not know in advance what you will later need to know. A scan captures everything — including the pillar you only notice three weeks later, when the kitchen has to be planned.
Practical tip: walk along the walls instead of standing in the middle of the room turning around. And always ask the agent first; it is still a stranger's home.
Situation 2: You are sitting at home with a property listing
Draw. There is nothing to scan. Draw the rooms up from the listing's measurements, and be aware that a listing's floor area is, as a rule, measured externally, while your own rooms are measured internally. Your total will therefore come out smaller — that is not a mistake.
Treat the numbers as an estimate until you have been there with a tape measure. A drawing made from a listing is a good plan, not a takeoff.
Situation 3: You need a quote from a contractor
Scan, and verify by hand. A quote is calculated on surfaces: wall area, floor area, ceilings, number of doors and windows. A scan gives you all the surfaces at once, including the corners and projections that cost extra labour hours.
But always measure one control dimension per room with a tape before the numbers leave the house. A binding quote calculated on a wrong ceiling-height figure helps neither you nor the contractor. Send the takeoff along as a basis, not as gospel — a contractor who has to give a fixed price needs to see the room themselves.
Situation 4: You are planning a renovation
Both. Scan the home as it is — that is your starting point, and it needs to be measured, not guessed. Then draw the proposal on top: the wall to come down, the opening to be cut through, the extension to go up. A scanner can only measure what is there; the drawing board can draw what is not.
One thing neither a scan nor a drawing can settle: whether a wall is load-bearing. That takes a building surveyor or an engineer looking at the structure. No app can answer that, and none should pretend to.
Situation 5: You are painting or laying a floor
Either works, it does not much matter. For areas, the two methods are practically equal, because a couple of centimetres of disagreement is swallowed by the 5-10% waste allowance you add anyway.
The arithmetic: a room measuring 3.60 × 4.20 m is 15.12 m². If the scan is 8 cm narrower than reality, you get 14.78 m² — a difference of 0.34 m². If you buy flooring with an 8% waste allowance, you order either 15.96 or 16.33 m². You buy whole packs either way. The difference disappears.
Situation 6: Something has to fit between two walls
Tape measure — regardless of method. Kitchen units, built-in cabinets, a countertop, a sliding door. Here you need the smallest dimension, at the height the thing will sit, and you need to have measured it yourself.
Both a scan and a drawing can be off by a couple of centimetres, and a couple of centimetres is exactly the difference between whether the countertop fits. Use the floor plan to plan and the tape measure to order.
Situation 7: The phone has no LiDAR
Draw. LiDAR sits in the iPhone Pro models and in iPad Pro, not in the other models — the app itself will tell you if your device cannot scan. If you do not have a device with LiDAR, drawing is not a fallback. It is your method, and it gives a fully measured floor plan if you measure properly.
In HouseSense you draw the rooms on graph paper and enter the measurements in whole centimetres. From there there is no difference: area, floor plan, 3D model, takeoff, sun and reports all work on a drawn home exactly as on a scanned one.
Situation 8: The home is empty, dark, or packed to the ceiling
Depends which. An empty home is a scanner's paradise: every wall is free, and there is no furniture to mistake for a wall. A dark home can be scanned, because LiDAR measures with pulses of light and does not depend on room lighting — but turn the lights on anyway, since the software also uses the camera image to understand what it is looking at.
A home that is packed to the ceiling is the hard case. The scan measures the boxes, not the walls. Here a tape measure and a drawing are often quicker, and always more true.
Situation 9: You want to document the home before moving out
Scan. Once you have moved, you cannot measure it again. A scan captures the home as it was — including the details you did not know you would come to miss: the exact width of the windows, the ceiling height in the odd-shaped room, how far it was from door to corner.
If there are rooms you cannot reach, measure them quickly with a tape and draw them in afterwards. A room that is missing entirely makes the total wrong; a room that is roughly measured just makes it a little less certain.
The rule behind it all
Scanning and drawing are not two levels of quality. They are two ways of getting knowledge into the plan: either the sensor measures, or you do.
The scan is strong because it has no expectation of how the home ought to look. The drawing is strong because it can draw what is not there yet, and because it works without LiDAR and without you standing in the house.
What decides the quality is neither the method nor the equipment. It is whether the numbers were measured or guessed. A scan nobody has checked is no better than a drawing nobody has measured.