> For the complete documentation index, see [llms.txt](https://underwriting.homium.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://underwriting.homium.io/underwriting-property/appraisal-requirements/improvements-section-of-the-appraisal-report/gross-building-area.md).

# Gross Building Area

The gross building area

* is the total finished area including any interior common areas, such as stairways and hallways of the improvements based on exterior measurements;
* is the most common comparison for two- to four-unit properties;
* must be consistently developed for the subject property and all comparables used in the appraisal;
* must include all finished above-grade and below-grade living areas, counting all interior common areas such as stairways, hallways, storage rooms; and
* cannot count exterior common areas, such as open stairways.

Homium will accept the use of other comparisons for two- to four-unit properties, such as the total above-grade and below-grade areas discussed in Gross Living Area, provided the appraiser

* explains the reasons they did not use a gross building area comparison, and
* clearly describes the comparisons that were made.