Basement Waterproofing Cost Estimator
Enter your basement perimeter to estimate interior drain, exterior waterproofing, or sealing costs.
Runs entirely in your browser — your numbers never leave this page.
How it works
Not all “waterproofing” fixes the same problem — matching the method to the water source is the whole game:
- Interior French drain ($40–$100/linear ft): a perimeter channel cut into the slab that catches water under the floor and routes it to a sump pump. The standard fix for water seeping up through floor cracks or the cove joint.
- Exterior waterproofing ($106–$198/linear ft): excavate to the footing, apply membrane, add drainage. Stops water at the wall — thorough, but the digging roughly triples the price.
- Interior sealing ($5–$13.20/sq ft of wall): paint-on products like DRYLOK. Fine for dampness; useless against hydrostatic pressure pushing water through.
- Sump pump: usually bundled into the interior-drain price; a second pump on big basements runs ~$175–$225 for the unit.
- Battery backup ($1,000–$1,800): storms kill power exactly when you need the pump most — the cheapest insurance in the project.
Frequently asked questions
How much does basement waterproofing cost?
Interior French drains run $40–$100 per linear foot (a 120-ft basement: roughly $4,800–$12,000); exterior waterproofing runs $106–$198 per linear foot.
Interior drain vs exterior waterproofing?
Interior drains relieve water pressure under the slab and cost far less; exterior work stops water at the wall but requires full excavation around the foundation.
Does wall sealing stop a leaking basement?
No — paint-on sealers handle dampness only. Active leaks driven by hydrostatic pressure need a drain system, not paint.
How many sump pumps do I need?
One pump typically covers up to 130–150 linear feet of drain; larger basements need two.
Is a battery backup sump pump worth it?
Yes — power outages coincide with the storms that flood basements. A backup system runs $1,000–$1,800 installed.
What is the cove joint and why does it leak?
The seam where the basement floor meets the wall. Hydrostatic pressure pushes water up through it — the most common leak path an interior drain is designed to intercept.
Do I need a permit for waterproofing?
Often yes, especially for exterior excavation. Check with your local building department before digging — and call 811 for utility marking.
How long does interior drain installation take?
Typically 2–4 days for an average basement, with concrete cutting and re-pouring the trench.
Will waterproofing raise my home value?
A dry, documented basement removes a major buyer objection and makes finishing the space viable — appraisers notice both.
Can I waterproof a basement myself?
Sealing paint is DIY-friendly. Interior drains and exterior excavation need pros — mistakes redirect water into the house instead of away from it.