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Two ranges for the same basement
| Size | Owner-managed $7–$23 | Contractor basic $25–$40 | Contractor mid $40–$75 |
|---|---|---|---|
| 500 sq ft | $3,500–$11,500 | $12,500–$20,000 | $20,000–$37,500 |
| 700 sq ft | $4,900–$16,100 | $17,500–$28,000 | $28,000–$52,500 |
| 900 sq ft | $6,300–$20,700 | $22,500–$36,000 | $36,000–$67,500 |
| 1,100 sq ft | $7,700–$25,300 | $27,500–$44,000 | $44,000–$82,500 |
| 1,300 sq ft | $9,100–$29,900 | $32,500–$52,000 | $52,000–$97,500 |
| 1,500 sq ft | $10,500–$34,500 | $37,500–$60,000 | $60,000–$112,500 |
The gap is mostly the labor share (about 40% per This Old House) and the general contractor's overhead, which HomeAdvisor puts at roughly 20% of the budget. Doing the carpentry, drywall and paint yourself captures part of that. Most building departments still require licensed electricians and plumbers or a homeowner permit and inspection for that work.
Jobs worth hiring out
- Electrical panel work and new circuits.
- Drains below the slab and ejector pumps.
- Cutting the foundation for an egress window.
- Waterproofing and drainage.
- Moving ductwork and gas lines.
Jobs owners often do
- Framing walls with a treated bottom plate.
- Rigid foam insulation on the walls.
- Hanging and finishing drywall.
- Painting, trim and floating floors.
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 can I save finishing my own basement?
On a 1,000 sq ft basement, the owner-managed range ($7,000–$23,000) is well below the contractor basic range ($25,000–$40,000). Your saving depends on how much you actually do yourself.
Related calculators
Sources
- https://www.homeadvisor.com/cost/basements/
- https://www.thisoldhouse.com/foundations/reviews/cost-to-finish-basement
- https://www.blockrenovation.com/guides/basement-remodel-cost-per-square-foot-2026