Floor plans and square footage you can defend
Measured floor plans for listings, with the standard and method stated, so the size in the ad is a number you can explain.
Square footage is the number buyers argue about
Buyers compare homes by size and price per square foot, lenders and appraisers rely on it, and when the number in the listing turns out to be wrong it becomes a dispute. Most disputes come from the same few causes: the listing mixed interior and exterior measurements, counted a basement as living space, copied a figure from an old listing or a strata plan, or did not say how the number was produced.
A floor plan, ordered in the same listing package as the photos, fixes most of this. It shows the layout, gives room dimensions, and states the total area with the rules used to calculate it. The rules differ by province and country, and that is the part most people get wrong.
Measurement rules by jurisdiction
| Where | Who sets it | Is a method mandatory? | Key points |
|---|---|---|---|
| Alberta | Real Estate Council of Alberta (RECA): the Residential Measurement Standard (RMS) | Yes, licensees must use RMS when measuring and advertising residential property | Houses measured at the exterior of the foundation walls. Only levels entirely above grade count toward RMS area; below-grade space may be shown separately. Condos measured paint-to-paint inside the perimeter walls at floor level. Minimum ceiling heights apply (2.13 m, with 1.52 m for sloped ceilings). The condo's registered size cannot be used instead. |
| Ontario | Real Estate Council of Ontario (RECO), under TRESA | No. RECO has said there are no generally accepted standards for floor plan measurements in Ontario | Registrants must not publish false or misleading information. Verify measurements, or leave them out, or add a qualifying statement. Say if a finished basement is included. |
| British Columbia | BC Financial Services Authority (BCFSA) | No single standard is mandated | BCFSA advises verifying measurements, measuring strata units rather than relying only on strata plans, and separating the strata lot from exclusive-use areas such as balconies and parking. For commercial space it points to BOMA standards and asks that the source and method be disclosed. |
| Other provinces, including Québec | Provincial regulators | No national standard applies in Canada; check your regulator | Many measurers use RMS-style or ANSI-style rules by choice. The safest practice is the same everywhere: state the method. |
| United States | ANSI Z765-2021, published by the Home Innovation Research Labs | Required by Fannie Mae for appraisals since April 2022, and adopted by Freddie Mac; not a law for listing agents | Measured to the exterior of the house. Finished, above-grade space only; any level partly below grade is reported separately. Ceilings of at least 7 feet, with rules for sloped ceilings. Garages and unfinished areas excluded. Local MLS rules may add their own requirements. |
RECO, RECA and RMS are not the same thing
People often say “the RECO standard” when they mean RMS. RMS is Alberta's rule, set by RECA, the Alberta regulator. RECO is Ontario's regulator, and it does not require a particular method. An Ontario listing can use RMS-style measuring, and many measurers do, but it should say so rather than imply that a provincial standard applies.
The same care applies in the United States. ANSI Z765 is the standard most appraisers now use because the large mortgage buyers require it. If your listing uses a different method, the appraiser's number may not match yours, and the buyer will ask why.
How a floor plan is measured and drawn
Agree the standard
RMS for Alberta. For other provinces and the United States, agree which rules to follow before measuring, usually RMS-style or ANSI-style, and whether below-grade space should be shown.
Measure
Rooms and walls are measured with laser tools or a scanning camera, including wall thickness where the standard measures to the exterior. Stairs, openings to the floor below and low ceilings are recorded because the rules treat them differently.
Draw
A clean plan per level with room names and dimensions, doors, windows and fixed features, in metric, imperial or both.
Calculate and label
Totals per level and overall, with above-grade and below-grade shown separately and the method stated on the plan.
Add the site
Where the lot matters, a drone aerial gives the buyer the shape of the lot, the roof and the outbuildings. It is a marketing image, not a legal survey; mapped sites are a different product, see orthomosaics.
How measurement disputes start
Copied numbers
The size comes from a previous listing, the builder's brochure or the strata plan, and nobody checks it.
Basement counted as living area
A finished basement is added into the total without saying so, and the appraisal comes in smaller.
Tour measurements quoted as fact
A number read off a 3D model is used as the official size.
Marketing image treated as a survey
Lot lines drawn on an aerial are relied on for a fence or a subdivision.
Who relies on the number
Listing agent
- They need from you
- A size they can advertise without risk.
- You need from them
- Which standard applies and whether below-grade space is to be shown.
- On the DroneLink record
- The standard is stated on the order and on the plan.
Buyer's agent
- They need from you
- To check the number and explain it to the buyer.
- You need from them
- Nothing, if the method is on the plan.
- On the DroneLink record
- Share the plan from the project link.
Appraiser
- They need from you
- To compare like with like, often using ANSI rules in the US.
- You need from them
- A clear method, so differences can be explained.
- On the DroneLink record
- The plan shows exterior or interior measurement and grade levels.
Strata or property manager
- They need from you
- Plans for many units, measured the same way.
- You need from them
- Access and unit lists.
- On the DroneLink record
- One project per building, plans per unit; see property managers and strata.
Questions
What is the Residential Measurement Standard (RMS)?
RMS is the measurement standard that Alberta real estate licensees must use, set by the Real Estate Council of Alberta. Houses are measured at the exterior of the foundation walls, only levels entirely above grade count, and condos are measured inside the perimeter walls. Other provinces do not require it, though some measurers use it by choice.
Does Ontario have a square footage standard?
No mandatory one. RECO has said there are no generally accepted standards for floor plan measurements in Ontario. Registrants must not mislead, so they should verify the size, qualify it, or leave it out, and say whether a basement is included.
How is square footage measured in BC?
BC does not mandate one method. The regulator advises verifying measurements, measuring strata units rather than relying only on strata plans, and separating the strata lot from balconies, parking and other exclusive-use areas.
What is ANSI Z765?
ANSI Z765-2021 is the US standard for measuring single-family homes. It measures to the exterior, counts only finished above-grade space, and reports below-grade space separately. Fannie Mae has required it for appraisals since April 2022.
Does a finished basement count as square footage?
Under RMS and ANSI Z765 it is reported separately from the main above-grade total. In provinces without a mandatory standard, say clearly whether it is included.
Are condo sizes measured inside or outside the walls?
Under RMS, condos are measured inside the perimeter walls at floor level. Strata or condo plan areas can differ from what you would measure, so check before quoting one.
Can a drone measure the size of my house?
A drone map can measure the roof and building footprint, and the lot, from above. Living area is measured inside and at the walls from the ground. For legal boundaries you need a land surveyor. See how drone mapping works.
Tell us about your Miami site.
An address and what you need is enough to start. We reply with what it will take, who will fly it and when.