Comparing layouts is where a space plan earns its keep. A single arrangement can only be judged against your hopes; two arrangements can be judged against each other. This page works through one comparison: a small home for a couple who work from home, with a hall, a kitchen and living space of about 30 m², two bedrooms of about 12 m² (one used as a study) and a bathroom of about 5.5 m².
1. Hold the brief and the measuring basis steady
A comparison is only fair if the layouts answer the same question. Use the same room list and target sizes for each, measure every area the same way, and assume the same wall thicknesses. Here every area is a planning area, measured to the planning lines, which are the inside face of the external walls. The "after walls" figures use 120 mm partitions centred on the shared lines and 400 mm external walls built outward, the convention described in how to turn a space plan into a floor plan.
If one layout quietly adds a room, drops a target or uses thinner walls, you are comparing your edits, not the arrangements.
2. Draw the alternatives at one scale
The two layouts below use the same five rooms. A is compact: the living space runs across the back, and a short hall from the entrance serves the bedrooms and bathroom. B is long: the living space is at one end and a corridor runs past the bedrooms to the bathroom.
3. Measure the same things on each
| Measure | A · Short central hall | B · Bedroom corridor |
|---|---|---|
| Planning area (inside the external walls) | 7.6 × 9.0 m · 68.4 m² | 13.0 × 5.2 m · 67.6 m² |
| Outside footprint with 400 mm walls | 8.4 × 9.8 m · 82.3 m² | 13.8 × 6.0 m · 82.8 m² |
| Length of external wall (planning outline) | 33.2 m | 36.4 m |
| Hall | 5.5 m² · 8.0% of the area | 7.2 m² · 10.7% of the area |
| Bedrooms | 10.2 m² (3.2 × 3.2) and 16.5 m² (3.3 × 5.0) | 12.2 m² each (2.9 × 4.2) |
| Bathroom | 5.8 m² · 3.2 × 1.8 m | 5.9 m² · 1.4 × 4.2 m |
| Doors passed from the entrance to the living space | 3 (both bedrooms, bathroom) | None |
| After walls: bedrooms | 9.9 m² and 16.0 m² | 11.5 m² each |
| After walls: hall clear width | 0.98 m | 0.94 m |
Each row answers a question the brief cares about:
- The route from the entrance. In A, a visitor walking to the living space passes both bedroom doors and the bathroom door. In B, the living space opens off the start of the corridor and the bedrooms are further along it, a private wing.
- Room sizes and proportions. A gives one generous bedroom and one under 10 m² once walls go in; B gives two equal rooms of 2.9 × 4.2 m. Check the shorter side as well as the area.
- Circulation. A spends 8.0% of its area on the hall, B 10.7%, the price of keeping the bedrooms apart.
- External wall. B's long outline needs 3.2 m more external wall, about 10% more, for slightly less area. External wall is usually the more expensive kind.
- What the walls change. Both halls fall just under 1.0 m clear once partitions are added. In B the bathroom is 1.34 m clear across, too narrow for a bath across the room.
Circulation share and room minimums are discussed in how much circulation space a house should have and room sizes and clearances.
4. Name the trade-off in one sentence
A table can hide the decision. Write it as a sentence: A is compact and cheaper to enclose, but every visitor walks past the bedrooms and one bedroom is small; B keeps the bedrooms private and equal, but needs a long, narrow plot, more external wall and a cramped bathroom. If you cannot write the sentence, the layouts are either too similar to be worth comparing, or you have not yet measured what matters.
5. Choose against the brief, and say what is still open
For this couple, the study is used all day and visitors come in the evening, so a private bedroom wing matters more than a few metres of wall. B is the better starting point, on two conditions: the plot is at least about 14 m wide, and the bathroom is widened, for example by moving the corridor end wall or shrinking the second bedroom by 0.4 m. A would be the better choice on a narrow plot, or for a household that rarely has visitors.
Some questions the comparison cannot answer yet, and they should travel with the choice:
- Which way the plot faces, and so which rooms get the sun.
- Where the kitchen units go inside the living space, and whether they fit beside the doors.
- Whether a 0.94 m corridor is wide enough once doors open into it (a common working minimum is 0.9 m; how wide should a hallway be covers the detail).
What a plan comparison can and cannot show
Everything in this comparison is measured on a 2D plan: areas, widths, which doors a route passes, which rooms touch an outside wall. That makes it repeatable, and it makes it limited. "Passes no bedroom door" is a fact about the plan, not a promise of quiet. "Touches an outside wall" is not daylight until you know the orientation and the window. And no comparison of two sketches says whether either complies with local building regulations, which need checking for your jurisdiction.
How this works in Gridsnap
You can draw each alternative by hand as Spaces and read their areas, or, with Gridsnap Pro, let Layouts arrange your room list. Its cards show every option at the same scale with its outer footprint, and View details lists each room's target and clear area, clear width and proportion, the relationships met and missed and the walking routes. When one part of a layout is right, keep those rooms and rework the rest, and compare Current and Proposed side by side. The measured checks cover the sizes, connections and footprint limit you stated; the choice, and everything the plan cannot show, stays with you. The product overview is on the Space Planning page.