A floor plan of your house comes in handy more often than you'd think: getting a quote for a new kitchen, preparing an extension, checking that a sofa will fit, or showing the house to a builder without them having to come round. The hard part is rarely the software. It's the measuring. A neat plan that's 30 cm out wastes more time than it saves.
This guide follows the order that avoids mistakes: measure first, put a base map down at the right scale, draw the outside before the inside, and check at the end. The examples use Architektor, which is free and runs in your browser, but the measuring method works with any floor plan software.
What you need before you start
- A 5 m tape measure and, if you can, a laser measure. The laser is quicker for long runs; the tape is more reliable for wall thicknesses and window reveals.
- A sheet of paper and a pencil for a rough sketch. It doesn't need to be pretty: it's there so you write each measurement in the right place.
- Any documents you already have: old architect's drawings, the drawings from a past planning application, the title plan, a land surveyor's boundary survey. Even old ones give you reference points. If they're in feet and inches, convert as you go: the editor works in metres.
- An hour or two for a typical ground floor, measuring included.
Measure the house
Start with a sketch of each floor, room by room, with the doors and windows. Then measure in this order:
- The internal length and width of each room, wall to wall, at floor level or just above the skirting boards.
- The thickness of the walls, in the reveal of a door or window. It's the only place you can read it directly.
- The external length of each elevation, corner to corner.
- The openings: width, distance from the corner of the room, and for windows the sill height (from the floor to the bottom of the window).
- The diagonals of the larger rooms. If the two diagonals of a rectangular room differ by more than a few centimetres, the room isn't square and you'll need to draw it as a polygon rather than a rectangle.
The most useful check happens on site: add up the internal lengths along one elevation plus the wall thicknesses, and compare with the external measurement. A 4.20 m room between two 40 cm walls should give 5.00 m outside. If it's more than 5 cm out, either a measurement is wrong or a wall isn't as thick as you think. A cavity wall, an old solid brick wall and the stone wall of a cottage are all different. Better to find out now than when you're drawing.
| Measurement | Where to take it | Common trap |
|---|---|---|
| Room length | At floor level, wall to wall | Measuring over furniture or a deep skirting board |
| Wall thickness | In a door reveal | Forgetting the plaster or internal insulation |
| Elevation | Outside, corner to corner | Measuring along a wider plinth at the base of the wall |
| Window | Width of the opening, masonry to masonry | Measuring the frame instead of the opening |
Put down a base map to scale
Create a project, then type your address: Architektor places the aerial view of your plot at real scale. In the UK and Ireland this is satellite imagery; official orthophotos are only available for Belgium (Wallonia, Flanders and Brussels). You then draw on top of it, like tracing paper.
Keep in mind that the photo is a guide, not a survey. From above, a house looks bigger than its walls because of the roof overhang, which can stick out by several tens of centimetres. Trees hide boundaries and shadows distort outlines. Use the photo to put the house and the plot in the right place, then trust your measurements for the dimensions.
No precise address, or a better document to hand? Import an image or a PDF (architect's drawing, title plan, scan), then calibrate it: click two points whose real distance you know and type that distance. Pick two points far apart, such as the two ends of an elevation with a written dimension: a click that's a few pixels off matters far less over 12 m than over 2 m. Then check another known dimension with the Measure tool.
Draw the plot boundary
With the Area tool, choose “Plot boundary” and click the corners of your plot, or drag for a rectangle. The area is shown in m² and in ares.
The best source for boundaries is a boundary survey by a land surveyor. In England and Wales, the title plan from HM Land Registry generally shows only general boundaries, not the exact legal line: fine for a garden layout, not for settling a disagreement with a neighbour. If the two don't match, draw the surveyor's version and note the difference in the element's Notes field.
Draw the external walls
Pick the Wall tool (W key), set the status to “Existing” and start at a corner of the house you're sure of. Click to place the first point then, instead of aiming at the next corner with the mouse, type the length: 8.4m or 840 then Enter. The wall is exactly 8.40 m long. Shift locks the angle to 45°, Alt turns off snapping, Esc or a double-click finishes.
Go all the way round the house. The last wall should land back on the first point: if it's a few centimetres short or over, that's the moment to go back to your elevation measurements, not to fudge the length.
Then set the wall thickness in the Properties panel. An accurate plan depends on it: with walls that are too thin, every room comes out too big.
Add partitions, doors and windows
Internal walls are drawn the same way, with their own thickness, often much thinner. Start from an external wall and type the length you measured inside.
For openings, pick the Door / window tool (O key) and click on a wall. Choose the type (door, double door, sliding door, window, garage door or open bay), then set the width, the position and, for a window, the sill height. You can flip the way a door swings in the properties. It matters when you plan furniture: a door that opens against the wall and one that opens into the room don't leave the same space.
Draw the rooms and read the floor areas
The Room tool (R key) creates a room when you drag a rectangle, or when you click its corners for any other shape. The area is worked out for you. Draw rooms to the inside face of the walls, not along their centre line: that gives you an area close to what you'd measure on the floor.
That figure is a geometric measurement, not a certificate. The floor areas used to sell or let a property, or for a planning application, follow precise definitions that vary from country to country (what counts under a sloping ceiling, walls, stairs and so on). For those uses, ask the professional concerned.
You can pick a floor finish for each room (parquet, tiles, polished concrete and so on): handy for estimating quantities, always with a margin for offcuts.
Handle floors and stairs
A new project already has several levels: underground and utilities, garden and outdoor, ground floor, first floor. When you draw the first floor, the other levels stay visible, faded, so you can place the upstairs walls exactly above the ground-floor ones. Double-click a level to show it on its own.
The Stairs tool offers straight, quarter-turn and spiral stairs. Enter the number of steps and the level they lead to: Architektor works out the riser height, the going and the Blondel comfort index (2 risers + 1 going, ideally between 60 and 64 cm). If your existing stairs fall outside that range, it isn't a drawing mistake: plenty of old staircases are steep.
Add the garden around it
A house without its plot doesn't tell the whole story. With the Area tool, add the patio, the path, the drive and the lawn; place the trees with the real diameter of their crown; draw fences and hedges. If you have a rainwater tank, a septic tank or inspection chambers, put them on the underground level. Each of these has its own guide: draw a garden plan to scale, where to put a swimming pool and mapping underground pipes and cables.
Check, save a version and export
Before you show anyone your plan, check three or four known dimensions with the Measure tool (M key): the length of an elevation, the width of a room, a diagonal. Add permanent dimension lines (D key) wherever a tradesperson will need them.
Then save a named version (⌘S, or Ctrl+S), for example “Existing, measured November”. Your work is saved continuously, but a version is a clear point to come back to before you start drawing projects. To try out an idea without touching this survey, create a variant.
For paper, export an A3 or A4 PDF. Architektor picks the largest standard scale that fits the plan on the sheet (1:50, 1:100, 1:200 and so on) and shows it in the title block, with a scale bar and a north arrow. Only visible levels are exported: hide the first floor to print the ground floor on its own. For an opinion from a distance, create a share link: the other person opens the plan without an account, measures and comments directly on it.
Mistakes that throw a plan out
- Mixing internal and external dimensions on the same elevation. Always note on your sketch which side you measured from.
- Forgetting the wall thickness, or using the same one everywhere when load-bearing walls, stud partitions and insulated walls all differ.
- Trusting the aerial photo for dimensions, when the roof overhangs the walls.
- Assuming everything is square. In an older house it rarely is: the diagonals will tell you.
- Drawing everything on one level, then being unable to print the ground floor without the first floor.
- Calibrating an imported plan over a short distance. Use the longest reliable dimension on the document.
With a clean survey, everything else gets easier: placing an extension, trying out a kitchen, drawing a patio. It's the foundation for every other project, including planning an extension or a conservatory.