ANSI Compliant Floor Plans: Why "Fully Compliant" Is an Illusion

No floor plan tool can be fully ANSI compliant on its own, because ANSI Z765 compliance is claimed for one house's square footage statement, and several of the rules behind that statement are calls about the house that someone has to confirm. Software can apply the standard's method, which makes a plan ANSI aligned; the figure becomes compliant when someone who knows the house has made those calls and stands behind the result.

What an ANSI Compliance Claim Is About

ANSI Z765 is the American National Standard for calculating the square footage of detached and attached single-family houses. It is a voluntary guide, and it has to be applied as a whole, so a figure that follows some of its rules and skips others doesn't follow the standard. It also asks for a statement with the result: finished area above grade and below grade reported separately, and a declaration whenever the figure comes from exterior dimensions alone, from plans or from estimated dimensions. Leave out a declaration that applies and, by the standard's own terms, any claim of adherence to it is void.

A compliance claim is therefore about one statement of square footage for one house. Fannie Mae's Selling Guide puts appraisers under the standard when they measure, calculate and report the square footage of a single-family home, hybrid appraisals included, and it adds that when they use sketching or 3D scanning software, the output must conform to ANSI Z765 as well.

Part of the method is mechanical, and software does it the same way every time. Measurements are taken to the nearest inch or tenth of a foot and the total is rounded to the nearest whole square foot. Garages and unfinished areas never count as finished, and openings to the floor below are left out. The nearest inch is how a measurement is recorded, though, and it isn't a tolerance: the standard sets none for how far two measurements of one house may differ.

The Figures a Scan Has to Assume

Some of the rules need figures that a scanner standing inside the house never records. ANSI Z765 measures a detached house at floor level to the exterior finished surface of its outside walls. An attached house is measured the same way, or from the centreline between houses where that is appropriate, and which of the two fits a shared wall is a decision in its own right. A scan from inside records the inside face of each outside wall, so to reach the exterior surface the software adds a wall thickness that it assumes or that someone sets. Where the real walls are thicker or thinner than that figure, the total moves with them, however carefully each room was scanned.

Walls inside the house raise the same question. When a finished room sits beside an unfinished one on the same level, such as a kitchen next to a garage, the standard measures the finished area to the unfinished side of the wall between them, which makes that wall the outside wall of the finished area. The line can only be drawn once someone knows which side is finished.

Protrusions are judged by their floor. A chimney or a bay window that juts out beyond the exterior wall stays out of the area when it has no floor on the same level, and one that starts at floor level and meets the ceiling height rules counts with its room. A scan can show whether a bay window has a floor, but not whether the room behind it counts as finished.

The Calls That Need Someone Who Saw the House

Finished area has to be suitable for year-round use, with walls, floors and ceilings similar to the rest of the house, and a bare or painted concrete floor doesn't count as a finish. The room's shape and height come from the scan; whether its finish matches the house and whether it can be lived in all year are judgements. A sunroom or an enclosed porch can be counted either way under the US standard, depending on the room.

Ceiling height is measured, and it decides where a finished room is reported. A room needs a 7 foot ceiling, or 6 feet 4 inches under beams and ducts. In a room with a sloped ceiling, at least half the finished area has to reach 7 feet, and nothing under 5 feet is counted. A finished room that falls short goes into the appraisal as nonstandard finished area, reported on its own line.

Grade follows a strict rule. ANSI Z765 counts a level as above grade only when all of it is above grade, and Fannie Mae treats a level as below grade if any part of it is. Giraffe360 notes that its software can't always detect a level that sits partly below grade, and asks customers to verify it when the project arrives. Garages are left partly to custom: the standard's commentary says its treatment of garage area lets practitioners apply local customs.

Aligned by the Tool, Compliant at Sign-Off

A floor plan tool can honestly claim to be ANSI aligned. That means the software applies the standard's method by default: it measures to the inch, rounds the total, keeps levels below grade out of the above-grade total, says which wall thickness it assumed, and lets someone change the calls it can't make. Compliance is claimed later, for one house, once those calls have been confirmed and the statement the standard asks for has been made. For a mortgage, the appraiser makes that claim, and Fannie Mae requires them to follow the standard whichever software produced the sketch. For a listing, Giraffe360's own guidance puts the responsibility for compliance on the user of the plan and recommends checking each plan for accuracy and suitability.

A "fully compliant" label printed on the software skips that step. The defaults may suit the house, and the label still can't say whether this sunroom is finished or whether this lower level sits partly below grade. A plan described as aligned, with its assumptions in view, shows the person signing what they still have to confirm.

Measuring is a separate question. A plan can apply every rule correctly and still carry a measuring error. How close a scanner comes to the true distance depends on its margin of error and on how carefully the capture was done, and the standard is silent on both.

What a Giraffe360 Plan Assumes, and Where You Change It

A plan from a Giraffe360 camera capture starts from defaults, and the calls among them can be changed. The standard comes first. A workspace sets it for new projects in Presets, under Property Data and Measurements, where the Area calculation standard is chosen separately from the units; projects already uploaded keep their own setting. During onboarding, Compare standards sets the options side by side before you choose. The product's guidance is to choose the standard your properties require, and never one picked to raise the total.

Under the United States standard, Giraffe360's reading of ANSI Z765 measures to the outside of the exterior walls and assumes the most common wall thickness, 6 in. It treats garages, sheds and attics used for storage as unfinished, puts a level above grade only if every one of its walls is, and starts every property as a house. A condo unit can be switched to an apartment once the project arrives, which leaves the exterior walls out of the area.

The calls from the house go into the floor plans in the floor plan editor. In Property data, the Grade level line in Buildings and floors is dragged to where the ground sits for Building 1. In Rooms, Edit measurements gives each room an inclusion category, so the sunroom can be Finished or Unfinished and a low-ceilinged room Non-standard finished. When you have a verified correction to a total, such as the Non-standard finished area, its pencil icon takes the new figure, and the revert control beside it brings back the calculated value.

The plan also states its own basis. The sidebar of each floor plan names the standard its calculations reference and says the measurements are approximate and not to scale, and Giraffe360 can't guarantee that the calculations match local requirements without the customer's input.