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If you have ever compared your home's square footage across different sources, you have probably noticed they do not agree. The county assessor says one number. The MLS listing from when you bought the home says another. Your original builder plans say something else entirely.
In Portland's diverse housing stock, square footage discrepancies are remarkably common, and they can have significant financial consequences when it comes time for an appraisal.
Why the Numbers Disagree
Square footage discrepancies arise from multiple sources, and understanding them helps explain why the number on your tax statement may not match reality.
County assessor records are often based on original building permits, sometimes dating back 50, 80, or even 100 years. If a homeowner later converted a basement, enclosed a porch, added a sunroom, or built an addition without pulling permits, the county records were never updated. The assessor's number may reflect the home as it existed decades ago, not today.
MLS listings rely on the selling agent's measurement or, more commonly, whatever number the agent pulled from public records. Agents are not trained in professional measurement standards, and the MLS number is frequently carried forward from listing to listing without verification.
Online estimates from Zillow, Redfin, and similar platforms simply echo the public record data. They do not measure anything.
How Appraisers Measure: The ANSI Standard
Professional appraisers follow the American National Standards Institute measurement guidelines, which provide a consistent, industry-wide methodology for calculating gross living area.
Key ANSI rules that affect Portland homes:
- Below-grade space does not count as GLA. Even a fully finished, beautifully appointed basement with bedrooms and a bathroom is not included in the above-grade gross living area calculation. It is noted and valued separately, but it does not inflate the primary square footage number.
- Space must be accessible from the interior. A room that can only be entered from outside the home, such as certain ADU configurations, may not qualify as part of the main dwelling's GLA.
- Ceiling height matters. Areas with ceiling heights below the ANSI minimum threshold are excluded from the GLA calculation.
- Measurements are taken from the exterior. The appraiser measures the exterior perimeter of the dwelling, not interior room dimensions. This typically produces a slightly larger number than interior measurements because it includes wall thickness.
The Financial Impact of Getting It Wrong
A 200-square-foot discrepancy might sound minor, but in Portland's market, it can translate to a meaningful valuation difference.
If comparable homes in your neighborhood sell for approximately $350 per square foot, a 200-square-foot error represents a $70,000 swing in value. In a divorce settlement, that discrepancy could shift the property division by tens of thousands of dollars. In a refinance, it could change your loan-to-value ratio enough to alter your terms.
This is why relying on public records or MLS data for square footage in a high-stakes situation is risky. The only reliable number comes from a professional measurement conducted during the appraisal process.
Common Portland Scenarios
Portland's housing stock creates several recurring square footage issues:
- Bungalow attic conversions: Many Portland bungalows have converted attic spaces with dormers. Whether this space qualifies as GLA depends on ceiling height, access, and whether it was finished with permits.
- Basement living space: Portland's older neighborhoods are filled with homes where the basement has been converted into living space over decades of incremental improvement. This space has value, but it is categorized differently than above-grade area.
- ADU and duplex configurations: Properties with attached accessory dwelling units require careful delineation of which square footage belongs to the primary dwelling and which belongs to the secondary unit.
- Enclosed porches and sunrooms: Portland's climate makes enclosed outdoor spaces desirable, but their inclusion in GLA depends on insulation, heating, and construction standards.
What You Can Do
If you suspect your home's square footage is inaccurate in public records, an appraisal is the most direct path to correction. The appraiser will conduct a professional measurement during the property visit and document the actual gross living area.
At Bernhardt Appraisal, we measure every property we appraise using current ANSI standards. We do not rely on tax records, MLS data, or assumptions. Our measurements become part of the permanent appraisal record, providing you and any future parties with accurate, defensible documentation of your home's actual size.
