Buying new construction from a floor plan: what to check before you sign

Conceptual model only. Not a survey or construction document.

The scale model, the renderings and the model unit are not made to be measured. The sales floor plan is. What to check on it before you sign.

A sales center is built to sell, so the scale model, the renderings and the model unit are not made to be measured. The one thing in the room you can audit is the floor plan for your own unit, and it is only worth auditing if it prints dimension strings. Read those numbers before you sign a purchase agreement or write an earnest money check, because the layout is what you are buying and the brochure image is not. This page is for a buyer of a pre-construction condo or a new-construction home who has the plan and does not yet have the keys.

What does a sales center actually show you?

The marketing floor plan is the only one of the five you can hold a ruler against, and it was still drawn to sell. Furniture printed on a sales plan is often smaller than furniture people own, which makes a bedroom read larger than it measures, and beds are the usual offender: a queen mattress is 60 by 80 in (152 by 203 cm) and a king is 76 by 80 in (193 by 203 cm). Line by line, that is how to read a builder’s floor plan. Before you argue about a room, check whether the sheet carries dimension strings at all. If it prints no numbers anywhere, you are reading a picture, and the first thing to ask the sales agent for is the dimensioned plan of your unit type.

Why the advertised square footage and the plan disagree

Two numbers can describe the same home and be measured by different rules. For attached and detached single-family homes, the Fannie Mae Selling Guide topic on the improvements section of the appraisal report requires an appraiser to follow the ANSI Z765-2021 standard, Square Footage, Method for Calculating, when measuring and reporting above-grade and below-grade area. The same topic adds the rule that matters if you are buying a condo: the ANSI standard cannot be used for apartment or multifamily buildings, and an appraiser measuring an apartment unit in a condo or co-op project must use interior perimeter measurements. It also says finished area that does not meet the ANSI ceiling height requirement is reported separately as nonstandard finished area, which is how a loft or a bonus room can drop out of a square footage figure you were quoted.

A developer’s marketing area follows neither convention automatically. It may be taken to the outside face of the walls, it may include a share of corridors and shafts, and it may be rounded. That is why a 3D model built from your plan, which measures the space between walls, rarely returns the number in the ad. Both figures can be honest at once, and why your floor plan and 3D model disagree on square footage explains where the difference goes. Ask in writing which measuring convention the advertised figure uses, and ask which area figure the purchase agreement carries.

What to check on the plan before you sign

1. Dimension strings. Get the dimensioned plan of your unit type, not the building sheet. Without at least one printed dimension, nothing else on this list can be verified from the drawing.
2. Wall thickness. An interior partition, a plumbing wall and a demising wall between units are drawn at different thicknesses, and the thick ones eat the room you thought you measured.
3. Door swings. The arc on the plan tells you which way a leaf opens and what it blocks: a closet door into a hallway, a bathroom door into the vanity, an entry door across a light switch. Clear opening width is narrower than the leaf, so read it as a doors and windows check rather than as decoration.
4. Window sizes. The plan usually gives a width, and the window schedule gives the rough opening. Ask for the sill height too, because it decides whether a desk, a sofa or a kitchen counter can sit under the glass.
5. Ceiling heights. Check the printed height for your floor and ask where it drops. Soffits for ducts, sprinklers and drainage show up on a reflected ceiling plan, not on the sales sheet, and top floors and podium levels often differ from the standard story.
6. Unit orientation. Ask which compass direction the windows face and what the next phase will build in front of them. Two units with identical square footage live differently at 4 pm.
7. Structure you cannot move. Columns, shear walls, plumbing chases and mechanical closets are permanent, and they are usually standing on the wall you wanted for the bed or the television.
8. The boundary of what you own. Corridors, the trash room, the elevator lobby, the amenity deck, the garage and often the balcony slab are common elements the HOA governs. Ask which line on the plan is the edge of your unit, and ask what the HOA rules say about that balcony.
9. Advertised area against the plan. Add the rooms up from the printed dimensions and compare the total with the number in the listing. A gap of a few percent is walls and rounding; a large gap is a different measuring convention, and you want it named in writing.
10. Standard against option. Islands, built-ins, a second sink, a pocket door and even a different door swing are sometimes drawn as though they were included. Get the finish and option schedule attached to the agreement, along with the developer’s substitution language.
11. The delivery route. If you are buying furniture for a high floor, ask for the elevator cab and door dimensions, the loading dock hours and the service corridor. A sectional that fits the living room can still fail at the elevator or in a stairwell turn.

What INK TO BRICK does with a sales floor plan

You upload the plan you already have, one file of up to 25 MiB as a PDF, PNG, JPEG, SVG, or DXF, and the conversion reconstructs a conceptual 3D model of that unit: rooms, walls, and openings you can inspect in a browser. For a single-floor upload, extract the required unit sheet as its own one-page PDF before uploading; the PDF floor plan route covers that preparation. Add drawing context you can verify: property type, floor level, ceiling height, original drawing units, scale denominator, and up to 30 reference measurements. The conversion interprets scale from the drawing and that evidence. One dimension string does not establish that every room is accurate, and omitting a reference does not by itself determine the result. Check the reported scale status and compare a second independent dimension before relying on the model’s distances.

Once the scale is resolved, the project reports overall width, depth and height, a space count, a modeled floor area and per-space dimensions, and a two-point measure tool takes any distance you want to bring back to the sales office. The editor’s Units control offers Metric or Feet and inches. For reference, 1 m is about 3 ft 3 in. Place pieces from the furniture library to see whether your bed, your sectional and your dining table leave a walking strip, and keep those changes in a saved design option on top of the locked existing conditions, so the reconstruction stays as drawn. Publish a showcase page and family can open the unit without an account. Exports carry it further: GLB and glTF, USDZ for AR, and PNG, JPEG or WebP images on Plus and above; DXF, DWG and SketchUp SKP on Creator and above; IFC and STEP on Business. Free covers one lifetime import of a public project. The allowances per plan are on pricing.

NoteConceptual model only. Not a survey or construction document. A model built from a sales plan inherits that drawing, including whatever the developer changes after it was printed, and it does not replace the area written into your purchase agreement, the appraisal, or a walk-through of the finished unit. Use this model for design exploration. Verify dimensions on site before ordering or building.

Walls and openings are locked in the app. A cleaner scan, the correct one-page PDF, or more drawing context can help when the source is missing information, but the reconstruction can also misread a legible drawing. A repeat import does not guarantee a repair. Record any discrepancy and do not treat a known geometry error as a reliable fit check. The longer version of this job is buying a home that is not built yet, and the conversion itself is described on floor plan to 3D.