Is GXX001 still valid?

No. Fannie Mae removed the GXX001- exception code in its June 2025 Selling Guide update, which applies to loan applications dated on or after September 8, 2025. Appraisers must now follow ANSI Z765-2021 in full, including any required declarations. If state law or regulation requires a different standard, the report must name that standard and explain how it was applied.

Does Fannie Mae require ANSI Z765 for condos?

No. ANSI Z765 covers single-family houses, not apartment or multifamily buildings, so it can't be used for condo or co-op apartment units. Fannie Mae has those units measured with interior perimeter measurements instead. Attached single-family homes such as townhomes and rowhouses do fall under the ANSI requirement.

Does Fannie Mae require ANSI for desktop appraisals?

No. Fannie Mae's desktop appraisal policy (Selling Guide B4-1.2-02) says ANSI Z765 is not required for desktop appraisals but is encouraged when feasible. A floor plan is still required. Hybrid appraisals are different: they need a floor plan that conforms to ANSI.

When did Fannie Mae start requiring ANSI Z765?

Fannie Mae's ANSI requirement applies to appraisals with effective dates on or after April 1, 2022. It covers hybrid appraisals and appraisals that require interior and exterior inspections of one-unit properties, including detached and attached homes, manufactured homes, townhomes and rowhouses. Freddie Mac followed for appraisals with effective dates on or after November 2, 2023.

Does Fannie Mae require ANSI for 2–4 unit properties?

No. Fannie Mae's July 2022 FAQ on its measuring guidelines says the ANSI requirement does not apply to 2–4 unit properties. It applies to one-unit single-family homes, attached and detached, appraised with an interior and exterior inspection or as a hybrid appraisal.

Guide

Fannie Mae's ANSI Z765 Requirement and the GXX001 Code

Fannie Mae requires ANSI Z765-2021 for measuring homes in appraisals. What it covers, what the GXX001 exception code was for, and what replaced it.

Updated October 12, 2026 · FloorFigures

Short answer

Fannie Mae Selling Guide B4-1.3-05 requires appraisers to measure and report square footage using ANSI Z765-2021 on hybrid appraisals and all appraisals with interior and exterior inspections, for appraisals effective on or after April 1, 2022. The old "GXX001-" exception code (often searched as GXXX001) is retired: since Fannie's June 2025 update, reports must follow ANSI in full, declarations included.

Fannie Mae adopted the ANSI standard to make square footage consistent from one appraisal to the next. The requirement itself is short. The questions come from the edges: which appraisals it covers, what to do with space that doesn't meet the standard, and what happened to the GXX001 code that many appraisers relied on.

What does Fannie Mae require?

Under Selling Guide B4-1.3-05 (Improvements Section of the Appraisal Report), appraisers must use ANSI Z765-2021 to measure, calculate and report above-grade and below-grade, finished and unfinished square footage. It covers attached and detached single-family homes, including manufactured homes, townhomes and rowhouses, and applies to "all hybrid appraisals and appraisals requiring interior and exterior inspections."

In practice that means the rules in ANSI Z765: measure to the exterior finished surface, keep below-grade levels out of above-grade area, apply the 7 ft ceiling rule, exclude garages and openings to below, and round to the whole square foot.

Which appraisals does it apply to?

Assignment	ANSI Z765 required?	Notes
One-unit home, interior and exterior inspection	Yes	Detached, attached, manufactured, townhome, rowhouse
Hybrid appraisal	Yes	The floor plan must conform to ANSI
Desktop appraisal	No	Encouraged when feasible; a floor plan is still required
Condo or co-op apartment unit	No	Measured with interior perimeter measurements
2–4 unit property	No	Per Fannie Mae's July 2022 FAQ
Apartment or multifamily building	Can't be used	ANSI Z765 doesn't cover them

Key dates

Date	What happened
April 1, 2022	Fannie Mae's ANSI requirement takes effect (appraisal effective dates on or after)
July 2022	Fannie Mae publishes its Standardized Property Measuring Guidelines FAQ
November 2, 2023	Freddie Mac's ANSI requirement takes effect (Bulletin 2023-15)
June 4, 2025	Fannie Mae updates the Selling Guide: GXX001- retired, GLA and basement terms replaced
September 8, 2025	Lenders must apply the June 2025 changes to loan applications dated on or after this date
November 2, 2026	UAD 3.6 mandatory for new reports first submitted to UCDP: six ANSI-based area fields

Does sketch or scanning software have to follow ANSI?

Yes. B4-1.3-05 says: "When using sketching or 3D scanning software, the resulting output must conform to the ANSI standard." A sketch program or phone scan that reports one total including the basement, or counts a two-story foyer twice, doesn't meet the requirement, whoever made it. The appraiser is the one who has to check. See appraisal sketch software.

What about space that doesn't meet the standard?

Fannie Mae gives two kinds of awkward space their own treatment:

Nonstandard finished area (NSFA): finished space that fails ANSI's ceiling-height rules or that you reach through unfinished space, like a finished room above the garage reached by garage stairs. Calculate it and report it separately, explain why it doesn't comply, and acknowledge any contribution to value. Above-grade NSFA rooms are included in the room count.
Noncontinuous finished area: attached finished space that isn't an accessory dwelling unit and has no interior access to the house. Report it on a separate grid line.

Neither goes into above-grade finished area. On the redesigned appraisal report they have their own fields; see UAD 3.6 and square footage.

What was the GXX001 code?

You may see it written GXXX001, with three Xs. The code Fannie Mae published was "GXX001-", with two Xs and a trailing hyphen. Either way, it is no longer in use.

When Fannie Mae first required ANSI, it allowed for assignments where the standard couldn't be followed. The appraiser entered GXX001- at the start of the Additional Features field and explained why. Typical cases were a berm home built entirely below grade, which has no above-grade area under ANSI, and states whose law required a different measuring method. Fannie Mae's FAQ was clear that the code could not be used to opt out of ANSI voluntarily.

What replaced GXX001?

No new code. Instead:

Follow ANSI in full. That includes the declarations: if your figures came from plans, an exterior-only measurement or estimated dimensions, the matching declaration is required.
Where the law requires something else, B4-1.3-05 now says "the appraisal report must note the standard required and explain how it was applied."
Space that doesn't qualify is reported as nonstandard or noncontinuous finished area, not hidden or forced into the main figure. A berm home simply reports its finished area as below grade.

What does Freddie Mac require?

Freddie Mac adopted ANSI Z765 in Bulletin 2023-15 (July 2023) for one-unit properties, excluding apartment-style condo and co-op units, for appraisals with effective dates on or after November 2, 2023. Both agencies now share the UAD 3.6 reporting rules and published a joint job aid (June 23, 2026) showing how ANSI areas go into the new report.

Do you have to state that you followed ANSI?

Fannie Mae doesn't require an affirmative statement that ANSI was followed. The standard itself, though, requires a declaration whenever the figures don't come from a full measurement of the house, and requires above-grade and below-grade figures to be stated separately.

Measuring a plan to ANSI rules

When you work from a builder plan, a listing floor plan or a third-party sketch, FloorFigures measures it with ANSI Z765-2021 rules applied: garage and porches carved out, openings to below subtracted, ceiling-height rules, below-grade levels kept separate, totals rounded to the whole square foot. It's free, and the plan never leaves your device. Add Declaration 2 when the figures come from plans. More for appraisers on FloorFigures for appraisers.

Sources

Fannie Mae Selling Guide B4-1.3-05 and B4-1.2-02.
Fannie Mae, Standardized Property Measuring Guidelines FAQ (July 2022, PDF copy).
Freddie Mac Bulletin 2023-15.

Questions

What was the GXX001 code?: GXX001- was a Fannie Mae exception code. An appraiser who could not follow ANSI Z765 on an assignment, for example on a berm home that is entirely below grade or where state law required a different method, entered GXX001- at the start of the Additional Features field and explained why. It could not be used to opt out of ANSI by choice. Fannie Mae retired the code in its June 2025 Selling Guide update. It is often searched as GXXX001, with three Xs, but the code had two.
Is GXX001 still valid?: No. Fannie Mae removed the GXX001- exception code in its June 2025 Selling Guide update, which applies to loan applications dated on or after September 8, 2025. Appraisers must now follow ANSI Z765-2021 in full, including any required declarations. If state law or regulation requires a different standard, the report must name that standard and explain how it was applied.
Does Fannie Mae require ANSI Z765 for condos?: No. ANSI Z765 covers single-family houses, not apartment or multifamily buildings, so it can't be used for condo or co-op apartment units. Fannie Mae has those units measured with interior perimeter measurements instead. Attached single-family homes such as townhomes and rowhouses do fall under the ANSI requirement.
Does Fannie Mae require ANSI for desktop appraisals?: No. Fannie Mae's desktop appraisal policy (Selling Guide B4-1.2-02) says ANSI Z765 is not required for desktop appraisals but is encouraged when feasible. A floor plan is still required. Hybrid appraisals are different: they need a floor plan that conforms to ANSI.
When did Fannie Mae start requiring ANSI Z765?: Fannie Mae's ANSI requirement applies to appraisals with effective dates on or after April 1, 2022. It covers hybrid appraisals and appraisals that require interior and exterior inspections of one-unit properties, including detached and attached homes, manufactured homes, townhomes and rowhouses. Freddie Mac followed for appraisals with effective dates on or after November 2, 2023.
Does Fannie Mae require ANSI for 2–4 unit properties?: No. Fannie Mae's July 2022 FAQ on its measuring guidelines says the ANSI requirement does not apply to 2–4 unit properties. It applies to one-unit single-family homes, attached and detached, appraised with an interior and exterior inspection or as a hybrid appraisal.