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Room plus window
HomeGuide puts the cost to finish one bedroom in a basement at $3,000–$12,000. Under IRC R310 every basement sleeping room needs its own emergency escape opening, so if the room does not already have a qualifying window, add HomeGuide's $4,000–$12,000 per egress window.
| Item | Low | High |
|---|---|---|
| Finish one bedroom | $3,000 | $12,000 |
| Egress window, cut in | $4,000 | $12,000 |
| Total with window | $7,000 | $24,000 |
What makes a basement bedroom legal
- An escape opening of at least 5.7 sq ft net clear, 24″ high and 20″ wide, with the sill no more than 44″ off the floor (IRC R310).
- A ceiling of at least 7 ft (IRC R305), with beams and ducts allowed down to 6′ 4″.
- At least 70 sq ft of floor and no wall shorter than 7 ft in plan (IRC R304).
- Smoke and carbon monoxide alarms as your local code requires.
Check these with the bedroom requirements checker.
Getting comparable bids
- Write a one-page scope: rooms, bathroom fixtures, number of egress windows, ceiling type and flooring.
- Ask each contractor to price the permit, the water fix and any electrical panel work as separate lines.
- Ask whether quotes include design, dumpster and final cleaning.
- Compare per-square-foot totals only after removing the bathroom and egress lines, which do not scale with area.
- Check the license, insurance and recent permits of each contractor with your building department.
The usual order of work
| Phase | Who | Notes |
|---|---|---|
| 1. Water and radon | Waterproofer, mitigator | Test radon and fix leaks before anything is covered |
| 2. Permit and plan | Owner, designer | Rooms, egress windows, bathroom location |
| 3. Egress and drains | Excavator, plumber | Cut windows and break slab for drains while the space is open |
| 4. Framing and insulation | Carpenter | Foam on the concrete, treated bottom plates, fire blocking |
| 5. Rough electrical, plumbing, HVAC | Licensed trades | Inspections before walls close |
| 6. Drywall and ceiling | Drywall crew | Leave access panels for valves and cleanouts |
| 7. Flooring, trim, paint, fixtures | Finish trades or owner | Final inspection |
Bathroom and egress costs land early, in phase 3, which is why they surprise people who budget only by the square foot.
Common questions
How much does it cost to add a bedroom in the basement?
$3,000–$12,000 for the room according to HomeGuide, plus $4,000–$12,000 if you must cut in an egress window.
Related calculators
Sources
- https://homeguide.com/costs/cost-to-finish-a-basement
- https://homeguide.com/costs/egress-window-installation-cost
- https://www.stpaul.gov/sites/default/files/Media%20Root/Safety%20&%20Inspections/DSI.Bldg_EgressWindow.pdf
- https://www.cityofboise.org/media/3924/434-irc-code-section-r305-ceiling-height.pdf
- https://shop.iccsafe.org/media/wysiwyg/material/7100S15-Sample.pdf