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How do I plan a renovation before calling a contractor?

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.

Why the order matters more than anything else

The typical renovation starts with a phone call and a feeling: "We are thinking of opening up between the kitchen and living room." The contractor comes round, has a look, guesses at a figure, and you are left with a loose estimate you cannot compare against anything.

That order costs money in two ways. First, contractors add buffer when they cannot see what they are walking into — uncertainty has a price. Second, the project changes as it goes, because no one has decided what it actually is, and every change made along the way costs more than the same change made on the drawing.

The right order is: measure → draw the current state → draw the desired state → write the list → settle the structure → get quotes. Anything that can be decided on the drawing should be decided on the drawing.

Step 1: Measure the home as it is

You need real measurements. Not approximate ones, not from the sales listing, not from the official property register — your own, internal measurements, wall to wall.

There are three ways to get them:

• Tape measure and paper. Measure each wall internally at floor height, measure the room's diagonal (it reveals whether the room is out of square), and measure the wall thickness in a door or window reveal. Allow about an hour for an average home.
• Scanning with LiDAR. If you have an iPhone Pro or iPad Pro with a LiDAR sensor, HouseSense can scan the rooms as you walk around and build the floor plan from that.
• Drawing it yourself in the app. In HouseSense you draw the home on a digital sheet of graph paper with your finger and type your own measured figures in whole centimetres. The drawing conforms to the numbers — not the other way round. It works on any iPhone and iPad, even without LiDAR.

Whichever route you take, you need to end up with the same four figures per room: length, width, ceiling height and area — plus wall thicknesses and the position of doors and windows.

Step 2: Draw the home as it is — and keep it

The drawing of the current home is not a stepping stone you throw away. It is the document everything else is measured against: the contractor's quote, the engineer's assessment, the authorities' handling of the case, and your own judgement of whether the result turned out the way you thought.

It needs to contain: every room with a name and area, every wall with a thickness, every door and window with a width and position, ceiling heights, and if the home has more than one storey: each floor on its own, showing which walls sit in the same place across several levels. That last point matters — it is the strongest clue to which walls form part of the home's load-bearing system, and it is usually the first thing an engineer asks about.

In HouseSense you get the floor plan as a PDF with measurements and areas, which you can send on by email. It is a much better conversation starter than a photo of a sketch on a piece of squared paper.

Step 3: Draw the change as a layer on top

Now draw what you want. Not instead of the current drawing — on top of it, so both exist.

In HouseSense you can draw and remove walls directly on the floor plan and place the change as a scenario layer, while the home as it stands today remains unchanged underneath. You can then switch back and forth and see the difference — and you can build several scenarios and compare them.

This is also where you spot the things that would otherwise only surface on site:

• How much unbroken wall space is left? A room with no walls is a room with nowhere to put a sofa or a tall cabinet. Reckon on: a sofa arrangement typically needs 80-120 cm of unbroken wall, a fridge 65-75 cm, a double bed 150-160 cm.
• Will the passage be wide enough? Allow at least 90 cm of clear passage, and 100-120 cm if two people need to pass each other.
• How much flooring needs laying? Under a removed wall there is no floor at all, and there are often two different floor finishes on either side. Add up the m² for the room that results.
• What happens to the light? In the 3D model with true sunlight, you can see whether the window you are counting on will actually reach into the new room — and at what time of day and year.

Step 4: Write the list — broken into line items

Now write down what needs doing. Not as a story, but as a list of lines a contractor can price individually. That is what makes three quotes comparable.

An example of a line-item list for an opening between kitchen and living room:

1. Demolition of wall between kitchen and living room, length 3.20 m, thickness 0.12 m, ceiling height 2.48 m — including protection of adjoining rooms.
2. Removal of debris.
3. Removal/relocation of 3 sockets and 1 switch in the wall, carried out by a licensed electrician.
4. Repair and painting of ceiling (strip 3.20 × approx. 0.15 m) and two vertical strips on cross walls.
5. New timber flooring in the combined room, 36.2 m², including skirting — client to supply the flooring.
6. Possible steel beam: pending the engineer's assessment, to be priced separately.

Notice two things: every line has a figure, and whatever is unresolved is listed as unresolved instead of being guessed at. Both give you a better quote.

Step 5: Settle the structure — the step that cannot be skipped

If the renovation involves removing or breaking through a wall, one question has to be answered before anyone can give a real price: does the wall carry any load?

You cannot decide that yourself, and no app can decide it for you. Wall thickness, whether the wall continues through the storeys, which way the floor structure spans, and whether there is a beam above — all of that is a clue, not an answer. The final assessment has to be made by a building surveyor or a consulting engineer who has been to the site and can produce the structural calculations.

Get that assessment into the plan before the contractor quotes — not after. It costs something, but it is cheaper than having a project priced when no one knows its scope. And remember: removing a load-bearing wall is an intervention in the home's structure, and that kind of work needs approval from the authorities before it starts.

This is where your drawing helps concretely: the engineer needs measurements, ceiling heights, wall thicknesses and the floor plans stacked on top of each other regardless. Bring those along, and the engineer's time goes on assessing instead of measuring up.

Step 6: Get at least three quotes on the same list

Send the same floor plan, the same scenario and the same line-item list to at least three contractors. Ask that the quote be broken into the same line items as your list — so you can compare line by line instead of staring at three lump sums.

Also ask for three things in writing: when the work can be carried out, how long it takes, and what is not included in the price. That last one is the most important. It is rarely the price of what was agreed that blows the budget — it is everything nobody had talked about.

One last thing: budget for what you cannot see

Add 15-20 % on top of the total budget for unforeseen issues. In older homes, make it 25 %. There is always something behind the wall: a pipe that was not on the drawing, a floor built up in two layers, a previous renovation done differently than assumed.

That is not pessimism — it is the only way to avoid having to make a bad decision halfway through the project because the money has run out. A renovation planned to completion on paper and budgeted with some slack almost always ends up cheaper than the one that started with a phone call.