Estimating additions and ADUs in St. Louis, MO
Prices for additions and ADUs in St. Louis, MO, how they compare with the national median and what to know when bidding here, for remodeling contractors.
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Room addition prices in St. Louis
Q4 2026 pricing. Ranges are rounded to the nearest $50, or $100 from $5,000 up.
1 story over a basement
$46,700 to $308,500
150 to 1,000 square feet
National median: $45,700 to $302,100.
2 story over a basement
$71,000 to $476,100
150 to 1,000 square feet
National median: $69,300 to $464,400.
How St. Louis compares
Across the work in the cost data, St. Louis prices run 3% above the national median.
More work in St. Louis
- Kitchen remodelsCabinets, countertops, appliances and finishes.
- Bathroom remodelsTile, fixtures, vanities and plumbing rough-ins.
- GaragesOne and two car garages, framed and sided.
- Decks and porchesFraming, decking, railings and stairs.
- PaintingInterior and exterior, by surface area and substrate.
- Electrical workService upgrades, rough-ins, fixtures and finish work.
- All of St. Louis, MOEvery category, against the national median.
- Additions and ADUs nationallyNational ranges, cost drivers and the estimate's structure.
Estimate additions and ADUs with St. Louis prices
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