Arm editing
Open the designer and arm editing — the Design door, or the B key.
Builder feature · free · in your browser
Draw Walls Online —Free 3D House Planner
Draw the outline, then the rooms — the engine surveys as you go. Builder's wall graph splits T and X junctions, mitres the corners and merges collinear walls, then computes every room and the perimeter straight from what you drew. Walls become exterior or interior by themselves. Nothing to tag, nothing to clean up.
How it works — in the app
Draw the outline
Draw the house wall by wall, then add interior walls the same way.
Watch the graph work
Close a shape and the plan comes alive: junctions split, corners mitre, rooms appear with measured areas.
Go up a floor
Add a storey when the ground floor is done — the foundation and floor slabs follow the plan.
What you get
Draw walls is one of fifteen feature pages covering what ships in Builder today — every claim here maps to a shipped, verified feature. The list below is the concrete surface:
- Junction splitting at T and X crossings — however you draw, the graph stays clean
- Mitred corners and collinear merge, so overlapping strokes resolve into one wall
- Rooms and the perimeter computed from the plan — areas are measured, not guessed
- Walls classify themselves exterior or interior — no tagging
- Multi-level building: storeys, foundation and floor slabs follow the plan
- Editing is one capability, armed only when you want it — a shared link stays read-only until you open the Design door
FAQ
Do I have to mark which walls are exterior?
No. Rooms and the perimeter are computed from the plan, and each wall is classified as exterior or interior by itself. That classification is what drives roofs, daylight and sections later.
Can I keep a clean plan if I draw roughly?
Yes — that is the wall graph's job. Junctions split at T and X crossings, corners are mitred and collinear walls merge, so a rough sketch resolves into a tidy, computable plan.
Is this a floor-plan tool or a 3D modeller?
Both, in one move: you draw the plan, Builder builds the 3D. Walls sweep round in 3D, openings are cut with real booleans, and cross-section views read the building back to you.
More Builder features
Keep reading the tour, or jump back to the Explore hub for all fifteen.
Cut windows & doorsCut windows and doors into your walls with real CSG booleans — rectangle, circle and triangle openings,…Open the feature →
Fit a roofPick one of four roof types and Builder auto-fits it to your exact perimeter — gable, hip, flat or shed —…Open the feature →
140 house designsStart from any of 140 original house designs — single storey, attic or two storey; gable, hip, flat or shed;…Open the feature →
Open the designer, draw four walls, and watch a house stand up around them.
No install, no plugin — a house builds itself the moment the page opens.