Walls are expensive detail at the start of a design. A space plan lets you test the more important decision first: how much of the building each activity receives, and where that space sits in relation to the others.
Keep planning intent separate from the building
A room begins as a requirement, not a wall. You might know that the kitchen needs a generous work zone, that the entrance should not open straight into a private room, or that two bedrooms must share a fixed amount of floor area. None of those decisions tells you the construction thickness or the exact position of a door yet.
Treat the early arrangement and the finished floor plan as two different drawings. The first is allowed to stay loose enough to change quickly. The second becomes precise building geometry. What is space planning? places that first drawing among the other stages of a design.
| Space plan | Building plan |
|---|---|
| What each space is for | What the walls physically enclose |
| Target and planned area | Actual clear room area after wall thickness |
| Adjacency and open/closed intent | Walls, openings, doors and windows |
| Fast to rebalance | Ready for documentation, 3D and analysis |
1. Start with the room list
Write one line for every space the project needs. Use names that describe the activity—Kitchen, Dining, Main bedroom, Hall, Utility—rather than Room 1 and Room 2. Give each a target area when you have one, but keep targets provisional: their first job is to reveal trade-offs, not to make every room pass a percentage test.
Separate the non-negotiable parts of the brief from preferences. A fixed total footprint, an existing stair position or a required entrance is a constraint. A slightly larger bedroom is a preference. When the arrangement cannot satisfy everything, this distinction tells you what to protect and what to rebalance.
Do not start by perfecting one room. Put every required space on the drawing first. A beautiful kitchen block is not useful if it leaves no credible route to the bedrooms.
2. Define the available footprint
If the building outline is fixed, draw that region before arranging rooms. This might be an existing house, a permitted extension, a structural bay or simply the maximum footprint the budget can support. The outline is a planning envelope: it tells you how much area is available, but it is not automatically a wall. When the outline is the hard constraint, planning rooms inside a fixed footprint covers the arithmetic of making everything fit.
If the footprint is not fixed, begin without an envelope and compare a few overall shapes. Add a boundary once the arrangement has a plausible width, depth and relationship to the site. A free layout is useful for exploration; an envelope is useful for proving that the proposal fits.
3. Place every space as a simple block
Start with rectangles where you can. They make area and proportion easy to read, shared edges easy to move and circulation gaps obvious. Use a polygon only where the footprint or the spatial idea genuinely needs a corner. Complexity at this stage should explain the plan, not decorate it.
Place the large or constrained spaces first, then the smaller spaces that can absorb change. Keep asking ordinary project questions: Which spaces need an exterior edge? Where does someone arrive? Which activities should connect directly? Which ones need acoustic or visual separation? Write the answers down as relationships. A planning tool can then measure whether an arrangement meets them, but deciding which relationships matter is still the designer's job.
4. Draw the route through the arrangement
Trace the journey from the entrance to every room with your eye or finger. If the route cuts through a furniture zone, crosses a private room or relies on a corner touch between two blocks, the arrangement is not resolved. Hallways, landings and vestibules are spaces in their own right, not whatever happens to remain after the rooms are placed.
Check the plan in both directions. The route from the front door to the living area may work, while the route from a bedroom to the bathroom does not. A space plan is useful precisely because those relationships can still change without redrawing a network of walls and openings.
5. Rebalance area, not isolated rectangles
Compare current area with target area across the whole plan. If one room is generous and its neighbour is short, move their shared boundary once; do not independently resize both and leave a gap or overlap between them. Recheck proportions as well as area. The same square metres can form a useful room or a narrow strip.
In Gridsnap, adjacent Space edges snap together exactly. A shared boundary gets a ⇔ handle that reallocates area between both Spaces, and either target can become a snap point. With a planning envelope, the Space Plan summary also reports unassigned area and any portion that sits outside the envelope. Overlaps are called out directly rather than hidden inside a total-area figure. The controls are in Draw and adjust spaces by hand.
Use the room sizes and clearances guide when you need a dimensional starting point, then test the particular furniture, circulation and regulations of your project before treating any target as final. The shares and the shared-boundary arithmetic are worked through in how to allocate floor area between rooms.
6. Decide what each shared boundary means
Two spaces touching does not always mean a wall should divide them. Review every meaningful shared edge and choose the intent:
- Wall asks for a physical interior wall.
- Open asks for no wall along that shared run.
- Auto means no explicit decision yet; Gridsnap currently builds it as a wall.
Use Open for a deliberate continuous space, not as a substitute for a door. A wall between two rooms still needs an opening wherever people move between them; deciding exactly where is the next stage. The point here is to settle the large spatial decision before choosing the opening.
7. Compare alternatives before committing
The first arrangement that fits is rarely the only good one. Before converting to walls, set two or three arrangements of the same room list side by side and compare them on the same terms: the route from the entrance, how private the bedrooms are, how much area goes to halls, whether any room has become a strip, and how much external wall each needs. Keep the brief and the way you measure identical, or the comparison measures your changes rather than the layouts. How to compare room layouts works through one comparison with the numbers.
In Gridsnap you can sketch alternatives by hand, or, with Pro, generate layouts that already meet your stated sizes and connections and compare them at one scale. When part of an arrangement is right, keep those rooms and rework the rest.
8. Build the wall plan
Build only when every required Space is present, overlaps are resolved and the boundary summary has no hard blockers. Soft findings such as unassigned area can remain if they are deliberate; the summary exists to make the decision visible, not to optimize the design for you.
Gridsnap's Build plan action converts the whole arrangement at once. Exterior edges use the Outer wall preset, internal Wall and Auto boundaries use the Inner preset, and Open boundaries receive no wall. Exterior walls grow outward; interior walls sit on shared planning boundaries. Gridsnap then detects ordinary rooms from the resulting walls and applies the Space names where it can.
Expect the actual clear room areas to differ from the planned allocations. Physical partitions occupy space, so each room gives up part of a wall thickness. Use the wall thickness guide to choose realistic construction values before treating the area comparison as final, and how to turn a space plan into a floor plan for the arithmetic of how much each room loses.
After Build Plan
The generated walls are ordinary Gridsnap walls: edit, extend or delete them like geometry you drew by hand. If the arrangement came from a generated layout, its planned doors are listed in Finish door placement and can be placed in one step; otherwise add them with the Door tool. Then add windows, dimensions, furniture and construction information in the normal floor-plan workflow. The wall plan is now authoritative; edits do not continuously reshape the earlier Spaces behind it.
Gridsnap keeps the Space Plan as read-only planning provenance. The Built from spaces control can show that source or reopen it as an editable variation. Building that variation can replace the current floor, or—on Pro—become a separate design option. A build is one undoable action, so an immediate undo restores the live draft. The whole sequence is in Build walls, place doors and make a variation.
What Gridsnap's Space Planning does not decide for you
- Generated layouts are proposals. With Pro, Gridsnap arranges the rooms and checks sizes, stated connections and a footprint limit; it does not judge daylight, views, furniture, door swings or regulations.
- Its checks measure what you stated. A relationship you never recorded is not checked, and a measured pass is not a verdict on the design.
- Build Plan creates walls and rooms, not doors or windows. A generated layout's planned doors are placed afterwards; windows and furniture are ordinary floor-plan work.
- It does not keep walls and Spaces synchronized. The building becomes authoritative after Build Plan.
- A planning envelope is not a wall or room. It only supplies the region against which gaps and outside portions are reported.
Space-plan checklist
- Every required activity has a named Space.
- Large and constrained Spaces are placed before leftover rooms.
- Every room has a credible route from the entrance.
- Target areas and room proportions have both been checked.
- There are no accidental overlaps or thin leftover slivers.
- Unassigned area inside the envelope is understood.
- Each shared boundary is deliberately Wall, Open or provisionally Auto.
- At least one alternative arrangement has been compared on the same terms.
- Wall presets are realistic enough for the area comparison to mean something.