Your floor plan is the document your home will be built from. If something is wrong or missing on the plan, it'll be wrong or missing in your house, and changing it after the slab is poured costs real money.
The good news is you don't need to be a draftsperson to read one. Here's what to look for on a typical Australian house plan.
C20 - What You Should Know When You Design Your New Home
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Last updated 28 Oct 2026 · Revision 3 · Free updates for life
Checklist Type: Minor
Form Factor: Fillable, print-ready PDF (A4, 42 pages)
When to use: Design stage: before the plans and specification are finalised and before you sign
A 134-check guide to work through with your designer while the plans are drawn. Settle the block, the sun, the layout, the energy rating, the services and the contract early, so a change costs a redraw, not a variation.
Start with the title block
The title block, usually in the bottom right corner, tells you the job address, drawing number, revision letter and date, and the scale. Always check you're looking at the latest revision. I've seen homeowners mark up an old version for weeks while the builder was working off a newer one.
Scale
House plans are usually drawn at 1:100 (1 mm on the plan equals 100 mm on site) or 1:50 for more detail. The scale is shown in the title block and only applies when the plan is printed at the stated paper size, often A3.
Never measure off a PDF printout or screen. It may not be printed to scale. Use the written dimensions instead.
Dimensions are in millimetres
Australian plans are dimensioned in millimetres. A room marked 3000 x 4000 is 3 m wide and 4 m long.
Room dimensions are usually taken to the frame, not the finished wall. Plasterboard, skirting and tiles take a little off each side, so a room will feel slightly smaller than the number suggests. If a fridge space or robe is tight, ask whether the dimension is to the frame or the finished surface.
Ceiling heights are usually noted on the plan or in the specification. Common heights are 2400 mm, 2550 mm and 2700 mm, and some rooms may be raked or higher.
Walls
Walls show as solid double lines. External walls are thicker than internal walls, and brick or block walls are often shown with hatching.
You can't tell which walls are load-bearing from the floor plan. That's shown on the engineer's framing and structural drawings, which you should also ask to see.
Doors
A door shows as a gap in the wall with a straight line for the door leaf and an arc showing which way it swings. Sliding doors show as two overlapping parallel lines in the wall, and cavity sliding doors as a line running into the wall.
Check every swing. A door that opens against a light switch, hits a toilet pan or blocks a hallway is easy to fix on paper and annoying for the next 30 years.
Windows
Windows show as thin parallel lines within the wall. Each one has a code, such as 1821, that links to the window schedule. The code is usually the height and width in hundreds of millimetres, so check your builder's schedule for how they've written it. The schedule also lists the window type (sliding, awning, fixed), glazing, and any obscure glass for bathrooms and toilets.
Dashed lines
Dashed lines usually show things that are above or hidden, such as eaves, bulkheads, overhead cupboards, raked ceilings or the roof outline. They don't mean a wall is non-load-bearing.
Other symbols worth finding
- Kitchen, bathroom and laundry fittings, such as the sink, cooktop, vanity, toilet and shower, drawn in outline
- Floor wastes in wet areas
- Downpipes, often marked DP
- Hot water system location
- Stairs, with an arrow showing the direction up
- Electrical items such as power points, lights, switches and smoke alarms. These are often on a separate electrical plan rather than the floor plan.
There's no single national symbol set, so if you see something you don't recognise, check the legend or ask your designer.
What to check before you sign off
- Flow. Walk through the plan in your head: carrying shopping from the garage, getting kids to bed, hanging out washing.
- Furniture. Measure your existing furniture and draw it on the plan to scale. Allow room to walk around beds and tables.
- Storage. Count the linen, broom and pantry space. Most people wish they had more.
- Light and orientation. Check where north is and which rooms get the morning and afternoon sun.
- Wet areas. Check shower sizes, floor waste positions and where the toilet faces.
- Consistency. Make sure the floor plan, elevations, electrical plan and specification all agree.
- Questions. If anything isn't clear, ask your designer or builder before you sign. Changes on paper are cheap. Changes on site aren't.
My C20 checklist on designing your new home (linked above) takes you through the decisions to make at this stage.
