All articles · 6 min read

Is a hand-drawn floor plan as good as a scanned one?

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.

What actually happens when a drawing "becomes a house"

A floor plan you have drawn with your finger on virtual graph paper starts out as nothing more than lines and numbers — a sketch you can correct, but not a "home" in the app's sense on its own. What happens when the drawing is turned into a real house is that the same lines get translated into the named building elements a scan would otherwise have produced: every line becomes a wall with a thickness, every marked opening becomes a door or a window with its own dimensions, every closed shape becomes a room with an area. From that moment there is no difference in how the app treats the data — the same floor-plan engine, the same 3D build, the same takeoff calculation.

This is a deliberate architectural decision, not a coincidence: an app with two separate data models for "scanned home" and "drawn home" would have to maintain everything twice, and every feature built for one would have to be built again for the other. By letting both paths land in the same data model, a drawn home automatically inherits everything a scanned home can do — floor plan, 3D, takeoff, budget, reports.

Where the difference still lives: the precision of the source

Even though the data model is the same, the source of the numbers is not. A LiDAR scan measures distances with a sensor that typically lands within a few centimetres under good conditions — reflective surfaces, very dark rooms or strong backlight can push the error higher. A drawing, on the other hand, has no sensor at all: every measurement is whatever you yourself typed in, whether it came from a tape measure, a laser distance meter, or — in the worst case — a guess.

That means a drawn home can end up either more or less precise than a scanned one, depending on how carefully you measured. A room you have measured with a laser in all four corners and typed in to the millimetre can easily be more accurate than a scan that was run quickly through a cluttered room. Conversely, a drawing where you have "roughly guessed" a couple of walls becomes less reliable than even a middling scan.

Can I use a drawn home for a contractor's quote?

Yes — under the same condition as a scanned home: the numbers must be measured, not estimated. A contractor asking for measurements for a quote does not care whether the numbers came from a scan or a drawing. What matters is whether the numbers can be trusted. The practical advice is therefore the same regardless of method:

• Measure with a tape measure or a laser, not by eye, when you draw a room from scratch.
• Note both the width and any deviations — if a wall is not quite straight, or a corner is not quite 90°, use whatever the drawing offers to mark it, rather than rounding it off to what you "know" it should be.
• Double-check the figures that cost the most to get wrong — an opening that is getting a new window or a new door tolerates no error, while a room's wall area for painting tolerates a couple of percent.
• Tell the contractor if some measurements were drawn from memory and others were properly measured — never mix the two without flagging it.

If the quote needs to be binding, most contractors will measure up themselves on site regardless of how good the source material is. A good drawing makes that work faster and cheaper — it does not replace it.

When is it better to scan than to draw?

• The room is irregular — curved walls, many angles, an old building without a single straight line. It is slow and difficult to draw precisely by hand, but trivial for a scan to capture.
• The home is large. Drawing 15 rooms with your finger takes noticeably longer than scanning them, even though the result is structurally the same.
• You want as many details as possible captured automatically — a scan picks up windows and doors you might forget to draw in by hand.

And conversely, drawing is often the better choice when you do not have access to the home — a flat you are considering bidding on, a house that has not been built yet, or a room you only have measurements for from an old building drawing. There is nothing to scan, but there are measurements to draw from.

Can the two methods be mixed in the same house?

Yes. If some rooms are easy to scan and others impossible — a loft room with no proper lighting, a room crammed with furniture, an extension that so far only exists as measurements on a piece of paper — you can scan what can be scanned and draw the rest. Both land in the same house, with the same kind of data, and the app cannot tell the difference afterwards. The only thing that stays different is how confident you yourself can be in the precision of the rooms you drew rather than measured with a sensor.

What HouseSense does

In HouseSense you can draw a home from scratch on the drawing board, with no LiDAR involved at all — and then tap the hammer to turn it into a real house inside the app, with area, floors, floor plan, 3D model, takeoff and reports. It is the same path a LiDAR scan ends up on, and anything a scanned home can be used for, a drawn home can be used for too. The difference does not lie in the app, but in you: a drawing is only as good as the measurements you yourself took, while a scan starts out with a sensor's own precision. When the numbers are being handed to a contractor or used in a decision that costs money to get wrong, the same rule applies either way — the drawing may be dressed up, the numbers may not.