Home Architect
Turn a map location or an empty plot into a measured floor plan, then check it against building rules, watch the sun move across it, walk through it in 3D, and price the build — all in the browser, with nothing uploaded.
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From a map pin to a costed floor plan, without a server
Designing a house starts with two things: a piece of land, and where north is. Everything downstream — which rooms get the morning sun, where the shadows fall in winter, how much wall you have to build — follows from those. Home Architect starts there. Paste a Google Maps link or type an address and the map centres on the spot; the coordinates are pulled straight out of the URL, so no mapping account or API key is involved. Building outlines come from the OpenStreetMap Overpass API, which returns real mapped footprints as polygons. If nothing is mapped where you are — common outside dense cities — switch to the satellite layer and click the corners of the plot yourself. Corners stay draggable, and the area and perimeter update as you move them.
That polygon is then projected onto a local tangent plane: metres east and metres south of the plot's own centre. Over a plot the error against a proper geodetic projection is a few centimetres, far below anything that matters for drawing walls. From that point on the drawing is in real metres, and the blueprint canvas is a true scale drawing rather than a sketch.
Rooms are not something you declare. They are worked out from the walls: every wall is split wherever another crosses it, endpoints within three centimetres are welded onto shared nodes, and the minimal cycles of the resulting planar graph are the rooms. Each connected group's largest cycle is its outline and is discarded; what remains are the enclosed spaces. That is why closing a gap in a wall instantly produces a room with an area, a name, a floor finish and a cost — and why leaving one open produces nothing.
The sun model is the standard NOAA approximation: day-of-year gives the solar declination and the equation of time, longitude and the clock give the hour angle, and from those come the altitude and the azimuth. Shadows on the plan are the wall footprints swept away from the sun by height divided by the tangent of the altitude. Direct sun per room is a different question and is answered separately: for every half hour of daylight, each window is tested for whether it faces the sun at all, and then a ray is cast towards the sun to see whether another part of the building is in the way.
Why we built this tool
Architectural software is either expensive, cloud-locked, or both, and the free web planners tend to want an account before they will show you a wall. None of that is necessary. A browser can already read a folder, do the astronomy, run the geometry and render WebGL, so a planning tool that never uploads a thing is perfectly possible — and for property data it is the right default. Where you live, what your plot looks like and what you can afford to build are nobody else's business.
The parts most people cannot do in their head are the ones we automated: whether a room is legal, whether the corridor is wide enough to carry furniture, whether the bedroom you put on the north side will ever see the sun, and what the whole thing might cost. The checks cover the common residential minimums — room areas, corridor and door widths, ceiling height, escape windows, the one-to-ten glazing rule, door swing clashes, bed clearance, the kitchen work triangle — and each finding says what the value is, what it should be, and where it is. Several offer a one-click fix.
It is a design and feasibility tool, not a substitute for a professional. It will tell you that a 7 m² bedroom is under the usual 9 m² minimum and that your hallway is 80 cm wide; it will not tell you the local code, the ground conditions, or what your municipality will approve. Drawings still need an architect or engineer to sign them off, and the estimate is a regional average, not a tender.
Getting good results
- If OpenStreetMap has nothing mapped at your address, do not fight it — press Satellite, then Trace plot, and click the four corners. It takes ten seconds and is usually more accurate than the mapped parcel anyway.
- Set the north rotation before you judge any sun result. It is under Properties with nothing selected, and every shadow, sun-hour figure and orientation score depends on it.
- Type while you draw: with the wall tool active, type
4.5and press Enter to commit a wall of exactly that length in the direction you are pointing. Hold Shift to invert the angle lock. - Rooms are named by dropping a room tag inside them, which the rectangle tool does for you. If a space shows as “Room” with a guessed type, click it and set the type — the type drives the minimum-area check, the floor finish and the cost per square metre.
- The auto-layout is a starting point, not an answer. Generate, then drag the walls: everything downstream — areas, checks, sun hours, quantities, the 3D model — recalculates as you move them.
- Sun hours are only as good as your windows. A room with no windows reports zero hours because it genuinely gets no direct sun, not because the maths failed.
Quick start: designing a house in Home Architect
- Open Site & plot and paste a Google Maps link, type an address, or press the crosshair to use your current position.
- Press Import OSM footprint to pull mapped outlines, or Satellite then Trace plot to click the corners yourself. Drag any corner to correct it.
- Press Use as site. The plot drops onto the blueprint canvas at true scale, in metres.
- Either describe the house in the Auto-layout tab (“3 bedrooms, 2 bathrooms, open-plan kitchen, south-facing balcony”) and press Generate, or draw walls yourself with the wall and room tools.
- Add doors and windows by clicking the wall they belong in, then drop furniture to test that the rooms actually work.
- Open Checks and clear the red items. Open Sun, set the date, and drag the time slider or press Play the day to watch the shadows move.
- Switch to 3D & AR to walk through it, and read the running total in Cost. Export the plan as SVG or PNG, the estimate as CSV, and the model as OBJ.
Everything — the map tiles you look at aside — happens in your browser. Projects are saved to this browser's own storage, and the .json export is your backup. There is no account, no upload, and no copy of your property on anyone's server.