Exterior foundation waterproofing
Keeping water off the outside of the wall is the most thorough fix and the most disruptive one. Here's what it takes.
Exterior waterproofing means excavating along the foundation down to the footing, cleaning the wall, repairing cracks, and applying a waterproof membrane or coating, usually with a drainage board over it. A perforated drain at the footing carries water to a sump or, on a sloped lot, out to daylight. The trench is then backfilled with soil that drains reasonably well, and the ground is shaped to slope away from the house.
When does digging make sense?
- You plan to finish the basement and want dry walls, not just a dry floor
- The original footing drain is missing, crushed or plugged with silt
- The house is cut into a hillside and the uphill wall takes most of the water
- Stone or brick walls are losing mortar to water coming from outside
- The wall has to be exposed anyway for structural repair
What makes it harder in Dubuque?
Steep lots, shallow rock and tight spacing. On the bluffs and in the older neighborhoods, houses can sit a few feet from the next one, with stoops, retaining walls and stairs in the way. Where bedrock is close to the surface, the trench may hit rock before it reaches the footing. And on a slope, the uphill trench gets deeper fast. A good company will tell you which walls can be done from outside and which are better handled with interior drain tile.
Before anyone digs
Iowa law requires anyone who digs, homeowner or contractor, to contact Iowa One Call through 811 at least two business days ahead, and the Iowa Utilities Commission recommends calling at least 48 hours before digging. The utilities then mark their buried lines. Your contractor should place that request and wait for the marks before excavating.
Questions to ask
- What membrane or coating will go on the wall, and how is it protected during backfill?
- Where does the new footing drain empty?
- How will lawn, plantings, steps and walks be put back?
- What happens to the plan and the price if the crew finds a damaged wall or hits rock?
What affects the price?
- Depth of the foundation and length of wall to dig out
- Machine access versus hand digging near utilities or tight spaces
- Concrete, steps, decks or retaining walls that have to come out and go back
- Wall repairs found once the foundation is exposed
We don't quote prices. The waterproofing company sets its price after someone has been in the basement, looked at the walls, floor joint and sump pit, and walked the outside to check gutters, downspouts and grading. Any figure offered before that visit is a guess.
Where we connect you with help
Common questions
Is exterior waterproofing better than interior drain tile?
It keeps water off the wall, which interior tile doesn't. It also costs more and tears up the yard. Which is better depends on your walls, your lot and what you want to do with the basement.
Can just one side of the house be done?
Yes. It's common to dig only the wall that leaks, often the uphill side on a sloped lot, and leave the others alone or treat them from inside.
Related services
More background: Dubuque basement water guide.
Water on the floor after a storm, or a sump pit that never rests?
Call and a Dubuque-area waterproofing company will come see what's going on.