Can a shared wall have two colours — one in each room?
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.
Short answer: Yes. A wall between a living room and a hallway is physically one wall, but it has two surfaces — one facing into the living room, one facing into the hallway. On a digital floor plan, colour is attached to the surface, not to the wall as a whole, so the living room side can be blue while the hallway side is white. That matches how painting actually works in real life: you choose colour room by room, not wall by wall.
Why we think of a wall as "one thing", when it isn't
When you stand in a room, you only see one side of the wall. It's easy to forget there's another room on the other side, with its own colour, its own floor and its own mood. A floor plan that works with two sides per shared wall matches the way a house is actually used: each room has its own character, and the boundary between them is invisible when you're standing inside one of them.
What "side" actually means on a drawing
On a 2D floor plan, a wall is a line with a thickness. That line has two edges — one facing into room A, the other into room B. Digitally, the two edges are typically stored as two independent surfaces, each with its own id, even though they share the same physical structure. That's the technical basis that lets colour, material and other choices be set independently on each side.
When does it make sense to colour the sides differently
- The rooms have different functions. A bedroom in a calm colour, a hallway or entrance in a more robust, light colour that doesn't show wear.
- You're planning to sell part of the property. A rental unit and a living unit can be painted so they read as two separate units even on the drawing.
- You want to see whether a colour "bleeds" visually. A bold colour on one side can read differently when you see the end of it from the neighbouring room in an open-plan layout — a drawing with two sides shows that more clearly than a drawing with only one colour per wall.
- The wall is already painted differently. If the house is older and already has different colours on the two sides of a wall, a drawing that only allows one colour per wall will always be wrong on one side.
What the colour on the drawing actually shows
The colour on a digital drawing is a visual marker — it tells you which room has which colour, and makes it easy to compare choices before you're standing there with a paint tin in hand. It's not a guarantee of how the colour will look in reality. The screen's colour rendering, the room's light and the paint's sheen (matt, silk, semi-gloss) all change how the same RGB value reads on an actual wall. Use the drawing's colour to plan and compare — use a physical paint sample on the wall itself for the final decision.
Does the colour carry through into the 3D model too?
In an app that builds 3D from the same drawing, colour typically works across the views: the same colour code you set on the 2D plan shows up on the wall in the 3D model and in any walkthrough of the house. That's a big advantage, because you can move from room to room and see the living room's blue wall meet the hallway's white wall exactly as it would look in reality — without having to paint twice to test the combination.
What about a completely ordinary, non-shared wall?
An external wall, or a wall that only borders one room, naturally only has one relevant side to colour — the other side, after all, faces the garden or the neighbour, not another room in your own home. The two-sided system only matters for walls that separate two rooms within the same property.
What a coloured drawing can't be used for
A coloured drawing doesn't tell you how many litres of paint to buy, and it doesn't work out the cost of the painting job for you. For that you need the actual wall area — minus windows and doors — and the paint's coverage rate, which is printed on the tin. The drawing is a decision tool for choosing and comparing colours, not a shopping list.
If the house is going to be sold — should you even paint it unevenly?
There are two schools of thought. One says a house that's going to be sold should be painted consistently and neutrally throughout, because that draws the fewest objections from a buyer who doesn't share your taste. The other says a room with character — a deep colour in a bedroom, a different one in a small guest toilet — helps a buyer imagine how the rooms can be used, instead of seeing an empty, white box. A coloured drawing is useful either way: you can see the whole house in one place and judge whether the variation reads as character or as clutter, before you put a single roller in the tin.
How do you choose a colour that matches the light in the room?
A colour that looks calm and light on a north-facing wall at midday can look completely different at dusk under artificial light, and a colour chosen in a south-facing room with strong sunlight can look pale and washed out in a room that never gets direct sun. That's one reason a digital colour sample — even a good one — can never stand alone. Hang a physical sample on the wall you're actually going to paint, and look at it at three points in the day: morning, midday and evening. Only then will you discover whether the colour "tips over" in one light or goes flat in another.
A concrete example: living room and hallway in open connection
Imagine a shared wall 3.2 m long and 2.4 m high between a living room and a hallway, with no door — just an open passage. Choose a dark colour in the living room and a light one in the hallway, and the transition between the two will read sharply, precisely because there's no door frame to visually mark the change. A digital drawing with two coloured sides shows you exactly that transition, including how sharp or soft the change is at the edge — something that's hard to picture from two paint samples held up next to each other in your hand.
What HouseSense does
In HouseSense you colour each wall side individually, directly in edit mode: tap the wall, choose a colour, and the choice applies only to the side you tapped. A shared wall between a living room and a hallway can easily end up with two colours. The colour carries through into both the 2D drawing, the 3D model and the walkthrough of the house, and it doesn't disappear even if you later go back to the original scan — the colour choice is a layer on top of the scan, not a change to the measurements themselves.
How to use it in practice
- Start with the rooms that border each other in an open plan. That's where you'll see fastest whether the colours match or clash.
- Test bold colours in a small scale first. A whole wall in 3D shows more than a 10×10 cm paint sample can.
- Save two or three combinations and step away from the screen. Colour choices you're instantly sure of rarely hold up best in the long run.
- Always buy a physical sample before you paint for real. The screen lies most about saturated, dark tones.