Exterior foundation waterproofing
Stopping the water on the outside of the wall is the most complete fix, and the most involved one. Here's what to expect.
Exterior waterproofing means digging 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 footer drain at the base of the wall carries water to daylight on a sloped lot, or to a sump. Then the trench is backfilled, ideally with material that drains well, and the soil is graded away from the house.
When is it worth the extra work?
- You plan to finish the basement and want the walls to stay dry, not just the floor
- The original footer drain is missing, crushed or clogged
- The house is on a slope and the uphill wall takes most of the water
- Old stone or brick walls are letting in water that's eroding the mortar
- The wall needs to be exposed anyway for structural repair
What gets in the way?
Porches, driveways, patios, sidewalks, mature shrubs and a neighbor's house a few feet away. On many older Altoona streets, homes sit close together or right up against the sidewalk, which can rule out digging on one side. Sloped lots can also make the trench deeper on the uphill side. A good company will tell you which walls can be done from outside and which might need an interior drain instead.
Before anyone digs
Pennsylvania law requires homeowners and contractors to call 811 at least three business days before digging, so PA One Call can have buried gas, water, electric and communication lines marked. Your contractor should place that call and wait for the marks. Ask too whether the job needs a permit from your municipality.
Questions to ask
- What membrane or coating will be used, and how is it protected during backfill?
- Where will the footer drain empty?
- How will the yard, plantings and walkways be restored?
- What happens if the crew finds a cracked or bowing wall once it's exposed?
What affects the price?
- Depth of the foundation and length of wall to excavate
- Hand digging near utilities or tight spaces versus machine access
- Concrete, pavers or porches that have to be removed and replaced
- Wall repairs found once the foundation is exposed
Every price comes from the waterproofing company itself, after someone has walked the basement, checked the walls and floor edge, and looked at the gutters and grading outside. We don't quote prices, and a number given over the phone before anyone sees the house is a guess at best.
Where we connect you with help
Common questions
Is exterior waterproofing better than an interior drain?
It keeps water off the wall itself, which an interior drain doesn't. It also costs more and disturbs the yard. Which is better depends on your lot, your walls and what you plan to do with the basement.
Can just one wall be done from the outside?
Yes. It's common to excavate only the wall that leaks, often the uphill side, and handle the others differently or not at all.
Related services
More background: Blair County basement water guide.
Puddles by the wall, a damp smell, or a pump that won't stop?
Call and a Blair County waterproofing company will come take a look.