How we turn building permits into prices

Most cost guides publish national averages without saying where they come from. We start from public records: the building permits that U.S. cities publish on their open-data portals. Every figure on this site states how many permits it is based on and when they were issued.

Where the data comes from

When a homeowner or contractor applies for a building permit, they declare the estimated cost of the work. We download residential permits from each city's open-data portal and keep those that describe a single type of project, such as a roof replacement or window replacement.

• Chicago: 5,104 permits across 5 project types, Jan 2025 – Nov 2026. Source dataset
• San Francisco: 7,897 permits across 7 project types, Jan 2025 – Nov 2026.
• Seattle: 407 permits across 3 project types, Jan 2025 – Nov 2026.

How we filter permits

We match permit descriptions and work types to each project, remove commercial and multi-unit buildings where the city marks them, and drop records with a missing or zero declared cost. Where the permit records the roof area or the number of windows, we divide the declared cost to get a price per square foot or per window.

What low, typical and high mean

• Low is the 25th percentile: one in four projects cost less.
• Typical is the median: half of projects cost less and half cost more.
• High is the 75th percentile: one in four projects cost more.

We only show a city-level figure when it is backed by at least 20 permits. When we do not have local data, calculators show a reference range built from the cities we do cover (lowest 25th percentile, median of the medians and highest 75th percentile), clearly labeled as such. We never estimate a local figure we have not measured.

Limitations

• The cost is declared by the applicant and can be lower than the final price.
• Text filters can let some commercial work through.
• Coverage is partial. Today we cover Chicago, San Francisco, Seattle, which are high-cost markets. Costs in most of the country are likely lower.
• Some work, such as gutters or most flooring, rarely needs a permit, so we do not publish figures for it yet.

All figures

The full table is available in our cost index, with a CSV download.

Data last updated November 11, 2026. We refresh it every quarter.