Floor Plan Checker
The mistakes are cheap on paper and expensive in concrete — find them while it's still a drawing
Nearly every bad room is bad for a reason that was visible on the plan. The door that hits the radiator, the bathroom you sidle into, the bedroom whose only window sits behind the bed head, the kitchen where the dishwasher door blocks the only route to the sink — all of them are millimetres on a drawing before they are money on a site. Gridsnap checks your plan for them while you draw it.
Not a style opinion and not a black box: seventeen rules applied to the actual geometry, each one pointing at the entities involved and the number of millimetres that is wrong. A badge in the editor keeps a live count; open it and each finding zooms the drawing to the exact spot.
What Gets Checked
Things that are physically impossible
FreeDrawing mistakes rather than design mistakes — the plan describes a building that cannot be built. These are checked on every plan, free.
Furniture overlapping furniture
Two pieces occupying the same floor. Chairs tucked under a table are fine, and so is a TV above its bench — the check compares real footprints and heights, not bounding boxes.
Furniture inside a wall or a doorway
A wardrobe half-buried in the partition, a cabinet standing in the opening. Common after a wall gets moved and the furniture doesn't.
Openings cut into each other
A window whose reveal overlaps a door's. Even a millimetre of overlap is a hole in the wall rather than two openings, and it is visible as a broken wall in 3D.
Doors and circulation
ProThe most common reason a plan that looks fine on paper is annoying to live in: you can see the rooms, but not the walking.
Blocked door swings and approaches
Both sides of every door need clear floor — roughly 800 mm of walk-up, plus the swept swing. A bookcase behind a door is a classic; so is a bed a door opens onto.
Doors swinging into each other
Two leaves that meet in the middle of the same space. Usually a hall with three doors within a metre of each other.
A route to everything
A walking route about 600 mm wide has to reach every door, every staircase foot and the working face of every piece of furniture, from the entrance. Solved as a route over the actual plan, so a sofa that seals off a corner is found even when nothing overlaps.
Slivers beside a wall return
A door left 5–100 mm from a returning wall: too narrow to plaster, too wide to be flush. Either push it flush to the corner or move it clear — the one-click fix snaps it flush.
Light and windows
ProRooms need daylight before they need furniture, and a plan is where daylight is won or lost.
Rooms with no window
A bedroom or living room without glazing — flagged once the floor has windows at all, so an unfinished plan isn't nagged.
Not enough glazing
The old rule of thumb: window area of at least an eighth of the floor area. Below that, the room reads as gloomy no matter how it's decorated.
Tall furniture in front of a window
A wardrobe against the glass. Measured against what you can see over — a dining set in front of a French window is normal and isn't flagged; a 2-metre cabinet is.
A bed head under a window
You sleep in the draught and can't open it from the bed. High sills (1200 mm and up) are exempt, because then it isn't behind your head.
A TV facing the window
A screen aimed straight at a big window fights daylight from morning to evening. Turn the seating group 90° at plan stage and the problem never exists.
Kitchens and bathrooms
ProThe two rooms where a few hundred millimetres decide whether the room works. They are also where retrofitting a fix is most expensive.
The work triangle
Sink, hob and fridge: no leg longer than about 2.7 m and no more than roughly 7.9 m in total. Too tight is as bad as too spread out.
Kitchen practice
A worktop landing beside the hob and the sink; an aisle of at least ~1050 mm between facing runs so two people and an open dishwasher door coexist; the hob not under a window; the fridge not hard against the cooker.
Fixture clearance
About 600 mm of clear floor in front of a toilet and 400 mm from its centreline to each side; roughly 550 mm in front of anything you open or stand at — wardrobe, fridge, basin.
Room too small to be that room
Advisory minimums by room type — a bedroom around 7 m² and 2.0 m wide, a living room 10 m² and 2.4 m, a kitchen 4.5 m², a bathroom 2.0 m², a WC 1.0 m² and 850 mm, a hallway 900 mm. Measured as the true narrowest width of the room, not its average.
Getting into bed
A double needs access down at least one side — around 400 mm — or someone is climbing over someone every night.
Explain, Then Fix
A finding tells you what is wrong; the next question is always what to do about it. Press the ✨ on any finding and you get an architect's note on that spot in your plan — what the rule is protecting, and a concrete suggestion for this geometry. It reads the finding and the surrounding context, never invents dimensions, and never touches the drawing.
Where the repair is unambiguous, there is a Fix button instead of a lecture — a deterministic geometric correction, one click, undoable like any other edit. And when a whole room needs rethinking rather than nudging, Furnish this room lays it out from scratch: the right pieces for the room type, zoned sensibly, placed flush to the walls they belong on, and checked by the same rules.
Why a Rule Engine Instead of a Model
Placement quality is checkable. "Is there 600 mm of clear floor in front of this toilet" is a measurement, not an opinion, and so is "can I walk from the entrance to that bed". Written as rules over real geometry, the answers are exact, repeatable, instant, and they come with the number attached — which is what makes them actionable. Language models are used where language is the problem: reading a brief, explaining a finding. The millimetres stay with the geometry.
Common Questions
What does the floor plan check actually do?
It reads the geometry of your plan — walls, doors, windows, rooms and furniture — and applies seventeen rules drawn from everyday drafting practice: clearances, door swings, circulation routes, daylight ratios, room minimums, kitchen and bathroom practice. Anything it finds appears as a list of findings in the editor; clicking one zooms the drawing to the exact spot.
Is it AI?
The checking is not — it is a deterministic rule engine working on the geometry, which is why it gives the same answer every time and can tell you the actual number of millimetres involved. AI sits on top of it, optionally: press the ✨ on a finding and it explains that specific issue in plain language with a concrete suggestion. Some findings also have a one-click deterministic Fix that simply repairs the geometry.
Will it reject my plan?
No — nothing is blocked or overwritten. Findings are advice, split into errors (mechanically impossible) and warnings (livability). Anything you disagree with can be dismissed and it stays dismissed. Rules of thumb are not building code, and a plan can be deliberately unusual.
Is this a building code compliance check?
No. These are conventions and rules of thumb that hold across most residential work — the things an experienced person would point out reading your drawing. Building codes are national, sometimes municipal, and change; check your own jurisdiction, and use a professional for anything being submitted for permission.
Which checks are free?
The mechanical impossibilities — overlapping furniture, furniture inside a wall, openings cutting into each other — run free on every plan, because a plan that cannot be built is a bug, not an opinion. The expert layer (circulation, clearances, daylight, kitchen and bathroom practice) is part of Gridsnap Pro at $9/month. Free users still see how many expert findings a plan has and in what category.
Can I check a plan I drew somewhere else?
Yes, by tracing it: import the PDF page, scan or photo as an underlay, calibrate the scale from one known distance, and draw over it. Once the plan is real geometry, every check applies. See converting an existing plan for the workflow.
The numbers behind these rules are collected in the room sizes & clearances cheat sheet. Checking a plan you drew elsewhere? Trace it first — editing an existing floor plan. Starting from nothing? Let the generator draw a first pass that already passes every rule.
Check your plan before your builder does
Draw it, and the findings appear as you go. Free to start, no account needed.
Open Gridsnap Editor