How Much Does Room Addition Cost in St. Louis, MO?
Average room addition costs in St. Louis range from $8,608 to $11,646. Get a free, customized estimate below.
Room Addition Cost Breakdown — St. Louis, MO
| Item | Unit | Qty | Unit Price | Total |
|---|---|---|---|---|
| Foundation | sq ft | 200 | $14.25 | $2850.00 |
| Framing | sq ft | 200 | $11.40 | $2280.00 |
| Roofing | sq ft | 220 | $7.60 | $1672.00 |
| Electrical & Plumbing | lump sum | 1 | $3325.00 | $3325.00 |
| Estimated Total | $10,127.00 | |||
* Prices are estimates based on St. Louis market rates. Actual costs may vary based on project specifics.
Estimate
Ref ID: EST-2026-PRFP
Date Issued
May 6, 2026
Client
Project Details
Site Address
Start Date
End Date
Scope of Work
Materials
| Material Specification | Units | Amount | Ext. Total | |
|---|---|---|---|---|
$ | $2,850 | |||
$ | $2,280 | |||
$ | $1,672 | |||
$ | $3,325 |
Labor
| Service Specification | Type | Hrs | Rate | Ext. Total | |
|---|---|---|---|---|---|
Craftsmanship Guarantee | $ | $600 |
Contractual Agreements & Conditions
Total
$10,727
Draft
Frequently Asked Questions — Room Addition in St. Louis
How much does room addition cost in St. Louis, MO?
The average cost for room addition in St. Louis, MO ranges from $8,608 to $11,646, depending on project scope, materials, and labor rates. St. Louis costs are close to the national average.
How do I get a free room addition estimate in St. Louis?
Use Brixor's free online estimate generator above. Enter your project details, customize line items for your specific needs, and download a professional PDF estimate instantly. No signup or credit card required.
What factors affect room addition costs in St. Louis?
Key factors include project size and complexity, material quality, labor rates in St. Louis (MO), permit requirements, accessibility of the work area, and seasonal demand. Getting multiple estimates is recommended.