Home Addition Cost in Miami: What 333 County Filings Show

An addition is a construction project, not a repair, and the declared values show it. Here is what attached-addition permits in unincorporated Miami-Dade were filed for.

What the records show

From November 2025 through October 2026, 333 home addition jobs were filed on houses in unincorporated Miami-Dade County. The middle job was valued at $39,500, meaning half were valued above that and half below. The middle half of jobs fell between $15,000 and $100,000. The work was filed by 173 different companies.

Why the values spread

Attached additions cover everything from a small covered porch or utility room to a new bedroom suite with a bathroom. That mix is why the range is so wide, and why the middle value is more useful than an average.

One caution: the value in these records is the declared value written on the permit when the job was filed. It is not a quote and not the final bill. The real cost can land higher or lower.

How to use the middle value

Treat $39,500 as a reference point, not a price. If a quote is far below the $15,000 to $100,000 range, ask what is left out. If it is far above, ask for a written breakdown. Then check that the company has filed similar jobs near you recently.

How we counted

• Source: Radar's permit database, built from Miami-Dade County building department records (permits issued by the County, which means unincorporated Miami-Dade). It does not include cities with their own building departments (City of Miami, Hialeah, Coral Gables, Miami Beach, Homestead and others). Data as of 2026-11-04.
• Coverage: permits issued 2025-11-03 to 2026-10-30. Every month in the window has filings (no gap): 2025-11 20, 2025-12 27, 2026-01 34, 2026-02 32, 2026-03 24, 2026-04 33, 2026-05 18, 2026-06 24, 2026-07 27, 2026-08 36, 2026-09 25, 2026-10 33.
• Which permits count: County BLDG permits with application type ADDITION - ATTACHED (the master permit itself); residential (ResidentialCommercial R), single-family or duplex use, issued 2025-11-01 to 2026-10-31.
• Values: EstimatedValue kept if 5000 <= value <= 1500000; null/zero/outside excluded from value stats only. 296 of 333 permits had a usable value. Median and middle half (25th to 75th percentile) use those.
• What the value is: the declared permit valuation, not the final price.
• Groups with fewer than 20 permits are not shown. No homeowner names or addresses are used.