Exterior foundation waterproofing
Keeping water off the outside of the wall is the most complete fix, and the most disruptive. Here's what to expect.
Exterior waterproofing means excavating along the foundation down to the footing, cleaning the wall, and applying a waterproof membrane or coating with a drainage board over it. A perforated footing drain at the bottom carries water to daylight on a sloped lot, or into a sump. The trench is backfilled, ideally with material that drains well, and the soil on top is graded to slope away from the house.
When is it worth the extra disruption?
- You're finishing the basement and want dry walls, not just a dry floor
- The original footing drain is missing, crushed or packed with silt
- The house is cut into a hillside and the uphill wall takes most of the water
- An old stone or brick wall is losing mortar to water coming through it
- The wall has to be exposed anyway for structural repair
What makes it hard on some lots?
Porches, driveways, patios, mature trees, gas meters and a neighbor's house a few feet away. Many older streets in Binghamton, Johnson City and Endicott have houses set close together with a driveway down one side, which can rule out digging on that wall. Hillside lots in Vestal and on the city's hills can mean a deeper trench on the uphill side, and glacial till full of cobbles can slow the digging. A good company will tell you which walls can be done from outside and which are better handled with interior drain tile.
What has to happen before anyone digs?
New York's one-call rules require excavators to contact Dig Safely New York by calling 811 at least two and no more than 10 full working days before digging, so utilities can mark buried gas, electric, water and communication lines. Your contractor should place that call and wait for the marks. If you're digging yourself, NYSEG says it's prudent for homeowners to call too. Ask, as well, whether the job needs a permit from your municipality.
What should I ask?
- Which membrane or coating will be used, and how is it protected during backfill?
- Where does the footing drain empty?
- What will the yard, plantings and walks look like when you leave?
- What happens to the plan and price if the wall turns out to be cracked or bowed once exposed?
What affects the price?
- Foundation depth and length of wall to excavate
- Machine access versus hand digging near utilities and tight spaces
- Concrete, pavers, steps or porches that come out and go back
- Repairs found once the foundation is exposed
Pricing comes from the waterproofing company after someone has been in the basement, looked at the walls, floor joint and sump, and walked the outside of the house. We don't quote prices, and nobody can give you an honest number over the phone before seeing where the water actually comes in.
Where we connect you with help
Common questions
Is exterior waterproofing better than interior drain tile?
It keeps water off the wall, which interior drain tile doesn't. It also costs more and tears up the yard. Which is better depends on your lot, your walls and how you plan to use the basement.
Can just one wall be waterproofed from outside?
Yes. It's common to dig only the wall that leaks, often the uphill side, and handle the rest from inside or leave them alone.
Related services
More background: Broome County basement water guide.
Wet floor edge, a weeping crack, or a sump that runs all night?
Call and a Broome County waterproofing company will come find where the water is getting in.