Key takeaways
- ANSI Z765 defines where you measure, not which tool you use.
- Ceiling heights, sloped ceilings, open-to-below areas, and finished vs unfinished space all need an interior view.
- UAD 3.6 does not require a floor plan for every property, but it does require structured interior data for every property.
Clarity, not alarm
UAD 3.6, together with the wide adoption of ANSI Z765-2021, is one of the biggest updates to appraisal reporting in years. Appraisers have been doing excellent work with UAD 2.6 and the tools they have. UAD 3.6 adds new structure; it is not a correction of what came before.
This guide covers what ANSI requires, what UAD 3.6 introduces, and where tools like BoxLi can make the transition faster and more predictable.
What ANSI Z765 requires
ANSI Z765 is the measurement standard for single-family residential properties. Appraisers have applied it for years and that does not change. What helps now is being precise about the interior rules.
- Measurement line: the exterior finished surface of outside walls for detached homes, and the centerline of common walls for attached homes. This defines where measurements are taken, not how.
- Ceiling height: finished area needs a ceiling of at least 7 feet. Beams, ducts, and similar obstructions may drop to 6 feet 4 inches.
- Sloped ceilings: space under 5 feet is excluded, and at least half of the room's finished area must have a ceiling of 7 feet or more for the room to count.
- Open-to-below areas: stairwell openings and two-story spaces are excluded from the upper level's square footage.
- Finished vs unfinished, above vs below grade: each must be reported separately.
None of these can be determined from an exterior outline. Ceiling height, slopes, and open-to-below space all need an interior reference point.
What ANSI expects you to understand
ANSI does not mandate a tool or a workflow. It expects the appraiser to know:
- Where interior boundaries fall
- How ceiling heights vary
- The geometry of sloped or vaulted ceilings
- Where knee walls sit
- Where finished space turns into unfinished space
- Where stair openings and open-to-below boundaries are
Appraisers make these calls every day. The change is that UAD 3.6 asks for them in a structured, standardized format.
What UAD 3.6 requires
UAD 3.6 does not require a full interior floor plan for every assignment. Layout diagrams are needed only when a property's design is atypical or functionally unusual. It does require a more structured dataset for every property, including:
- Room counts by level
- Interior functionality
- Floor plan relationships
- Interior condition
- Ceiling height characteristics
- Finished and unfinished areas
- Access relationships
Where exterior-only sketches fall short
Exterior perimeter sketches are still useful and familiar. The gap appears when the dataset asks for information the exterior does not show:
- Does the attic or bonus room meet the ceiling height rules?
- Where do ceiling height changes reduce qualifying area?
- What is finished and what is unfinished?
- Are there open-to-below spaces that change the calculation?
The modernization effort puts weight on standardization, defensibility, repeatability, and clear documentation. Traditional methods still work, but tools that capture interior detail quickly become more valuable.
How LiDAR helps
LiDAR does not replace appraiser expertise. It captures interior detail faster and with fewer chances to miss something. One pass with a LiDAR-equipped device records room geometry, wall relationships, ceiling height changes, sloped ceilings, open-to-below areas and stairs, and finished vs unfinished transitions.
BoxLi is built around a single scan of the whole home, minimal prep, and handoff to the appraisal software you already use. The output is machine-readable geometry that makes ANSI application clearer, UAD 3.6 fields simpler to fill, and documentation consistent from one assignment to the next.
Frequently asked questions
- What is the minimum ceiling height under ANSI Z765?
- Finished area needs a ceiling height of at least 7 feet, with obstructions such as beams and ducts allowed down to 6 feet 4 inches. Under sloped ceilings, space below 5 feet is excluded and at least half of the finished area must be 7 feet or higher.
- Does ANSI Z765 require a specific measuring tool?
- No. ANSI defines the measurement line and the rules for what counts as finished area. Tape, laser, and LiDAR are all acceptable if the rules are applied correctly.