FAQ · 4 min read

Does a Deck or Patio Count as Square Footage?

No. Decks and patios do not count as gross living area (GLA). Under ANSI Z765 -- the national standard for residential appraisals -- GLA must be above grade, finished, enclosed, and heated. A deck or patio meets none of those criteria.

Appraisers note decks and patios as site amenities and may give them contributory value in the appraisal, but they are never part of the GLA figure.

Why decks and patios are excluded

GLA must meet all of the following under ANSI Z765:

• Above grade. Must be above ground level. Patios that sit at or below grade fail this test.
• Finished. Must have finished floor, walls, and ceiling. Decks and patios have no enclosed walls.
• Enclosed. Must be accessible from the interior and enclosed on all sides. Decks and patios are open.
• Heated. Must be heated by a permanent system connected to the rest of the home.

A deck fails on finish and enclosure. A patio usually fails on all four criteria. Neither qualifies.

What about covered porches and screened enclosures?

A covered porch is still excluded from GLA. Having a roof does not change the classification -- the space still lacks finished walls and is not enclosed to the standard required for GLA.

A screened-in porch adds enclosure on three or four sides, but typically still does not qualify as GLA because it is not heated by a system connected to the home's main HVAC. Appraisers generally treat screened porches as an amenity, not GLA.

The one gray area: a sunroom or four-season room that is fully enclosed, finished (drywall, flooring, ceiling), and heated by the same system as the main house may qualify as GLA depending on how the appraiser assesses it and local market convention. If it meets all ANSI criteria, it can count. If it is a three-season room without heat, it does not.

Do decks affect the appraised value?

Yes -- just not through GLA. Appraisers adjust for outdoor amenities separately. A large deck, covered patio, or screened porch will typically contribute positive value in the sales comparison approach, as a line-item adjustment compared to similar homes that lack those features.

The contributory value depends entirely on market demand. In warm climates, outdoor living space may be worth $10,000 or more in value. In cold climates or markets where outdoor space is less prized, the adjustment may be minimal.

Can sellers advertise deck square footage?

Sellers and agents sometimes include deck or patio square footage in marketing materials, but this is not the same as GLA. If a listing says "2,800 sq ft including 400 sq ft deck," the appraiser will report GLA as 2,400 sq ft. Buyers should be aware of this distinction when comparing listings -- advertised square footage is not always appraisal-standard GLA.

Summary

Decks and patios do not count as square footage in any appraisal methodology. They contribute value as amenities, but they are never part of GLA. The only outdoor-adjacent space that could potentially count as GLA is a fully enclosed, finished, and heated sunroom that meets all ANSI Z765 criteria.