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How to Measure a New Construction Floor Plan

New construction homes come with architect drawings before the first nail is driven. Here is how to calculate accurate GLA from those drawings before the home is built.

Why measure from architect drawings

New construction appraisals are done on an "as-proposed" basis: the appraiser estimates value based on the plans before the home exists. Buyers, investors, and builders use pre-construction GLA calculations to verify what is being built matches what was advertised, size the home for financing, and catch plan discrepancies early.

Architect drawings are the most precise floor plans available. Every wall dimension is labeled. Scale bars are standard. GLA calculated from a professional architect's plan is typically within 0.5-1% of the completed home's actual measurement.

Getting the architect drawings

If you are buying a new construction home, the builder's sales office will have floor plan PDFs for each model. Request the full architectural drawing set, not just the marketing brochure floor plan. The architectural drawings include exterior dimensions; the marketing brochure often does not.

For custom builds, your architect produces the construction documents. The floor plan sheet (typically labeled A-1 or A2.0) shows the floor plan layout with all dimensions. This is your source file.

How to measure from an architect drawing

1. Open the floor plan sheet as a PDF and upload it to MeasureFloorPlan.com.
2. Trace the exterior perimeter of the above-grade living area. Architect drawings show the exterior wall line clearly. Follow that line, not the interior wall face.
3. Exclude the garage. Trace it as a separate polygon if you want its area.
4. Set scale from any exterior dimension shown on the drawing. Architect plans label exterior dimensions along each wall face.
5. For a two-story home, repeat for the second floor plan sheet.

Reading scale on architect drawings

Architect drawings include a scale notation in the title block (usually bottom right). Common residential scales: 1/4" = 1', 3/16" = 1', 1/8" = 1'. They also usually include a graphic scale bar.

However, these are only valid at the original print size. If the drawing has been printed at a reduced size (common when PDFs are saved from large-format originals), the stated scale ratio is no longer accurate. Always use a labeled dimension for scale calibration rather than the scale notation. See floor plan scale explained.

Verifying the builder's advertised square footage

Builders advertise square footage prominently. That number is sometimes GLA, sometimes total including the garage, and sometimes uses interior measurement rather than exterior. Compare your calculated GLA to what the builder advertises. If your number is significantly lower, the builder may be including spaces that an appraiser will not count as GLA.

This matters at closing: if the appraisal comes in at a lower GLA than was advertised, it can affect the loan-to-value ratio and potentially the purchase price.