Service
Exterior Basement Waterproofing in Janesville, WI
Exterior basement waterproofing in Janesville, WI runs roughly $7,000 to $18,000 according to 2026 national cost guides, because we dig down to the footing, seal the wall, and replace the drain outside. We do this when water presses against the foundation from the soil and has to be stopped before it reaches the wall. Call 123-456-7890 for a free inspection and a written price.
What Exterior Waterproofing Is
Exterior waterproofing treats the foundation wall from the outside, where the water first meets it. Interior drainage manages water that has already come through. Exterior work keeps it from getting in. We excavate along the wall, clean it, repair it, coat it with a waterproofing membrane, and install drainage at the footing so water moves away from the foundation instead of building against it.
It's a bigger job than interior drainage, and it costs more. It's also the right one when the wall itself is leaking or the original footing drain has failed.
What We Do on an Exterior Job
We excavate to the footing. We dig along the wall that leaks, down to the base of the foundation, so the whole wall face is exposed.
We clean and repair the wall. We remove old coatings and soil, patch cracks and mortar joints, and prepare the surface so the membrane bonds.
We apply a waterproofing membrane. A membrane sealed over the wall keeps water from passing through the block or concrete.
We install exterior drainage. A drain at the footing and a drainage layer against the wall carry water down and away from the foundation.
We backfill and restore. We fill the trench and leave the grade sloping away from the house.
Work is performed by independent professionals.
How it works
How an Exterior Job Goes
First, we inspect inside and outside to confirm the water is coming through the wall and not only the floor joint.
Second, we mark the walls that need work and check for utilities, decks, and walkways in the way.
Third, we excavate, clean, repair, and coat the wall.
Fourth, we install the footing drain and drainage layer and test where the water goes.
Finally, we backfill and regrade so rain runs away from the house.
When Exterior Waterproofing Fits
Exterior waterproofing fits when water comes through the face of the wall, when a footing drain has failed, or when the soil outside holds water against the foundation. It also fits when we can reach the wall easily. A wall with a deck, a patio, a porch, or a tight lot can make excavation costly, and in that case interior drainage and a sump pump may do the job for less. Many Janesville homes need only the interior system, and the inspection decides. For the full comparison, see interior vs exterior basement waterproofing.
Frozen ground slows excavation. The Afton-Janesville weather station records a January average low near 12°F and about 37 inches of snow in an average year, and March crosses freezing almost every day. We schedule exterior digging around the weather and tell you the timing in the written plan.
Why Janesville Foundations Need It
The ground around a Janesville foundation takes about 37 inches of precipitation a year, with the heaviest stretch from March through June at about 14.7 inches. Water builds against the wall each spring, and in a flash flood it builds fast. On April 17, 2026, storm runoff flowed into Janesville basements. About 28% of occupied homes in the city were built between 1960 and 1979, and another 27% before 1960, so many walls have gone decades without a membrane or a working footing drain. A wall that leaks through its face and a drain that has stopped working are the two cases where we dig.
What Exterior Waterproofing Costs in Janesville
Published 2026 national cost guides put exterior waterproofing at roughly $7,000 to $18,000. Those are national averages, not Janesville quotes. The length and depth of wall, the access, and the condition of the foundation move the price. A wall that also needs repair adds to it. We write the price after the inspection, before work begins. What basement waterproofing costs, and what changes the price
Frequently asked
Frequently Asked Questions
What is the difference between exterior and interior waterproofing?
Exterior waterproofing seals the foundation wall from the outside and installs drainage at the footing, so water is stopped before it reaches the wall. Interior drainage collects water at the base of the wall inside and pumps it out. Exterior costs more and means digging. Interior costs less and can go in any season. Which one a Janesville home needs depends on where the water enters, and an inspection settles it.
How much does exterior waterproofing cost in Janesville?
National cost guides published in 2026 put exterior waterproofing at roughly $7,000 to $18,000. Those are averages, not Janesville quotes. The price depends on how much wall is treated, how deep it goes, the access around the house, and whether the wall needs repair. We give a written price after an on-site inspection and before any work begins.
Does exterior waterproofing disturb my yard?
Exterior waterproofing means a trench along the treated wall, so landscaping, walkways, and sometimes decks along that wall are affected. We backfill the trench and regrade so water runs away from the house. Plants and hardscape near the wall may need to be moved or replaced. We mark what's in the way at the inspection and put the scope in the written plan.
Can exterior waterproofing be done in winter?
Exterior waterproofing is harder in winter, because frozen ground slows excavation. Janesville's January average low is near 12°F, according to the Afton-Janesville weather station, so we schedule digging around the weather. If water is entering the basement now, interior drainage can go in during any season, and exterior work can follow when the ground allows.
Do I need exterior waterproofing if my sump pump runs a lot?
A sump pump that runs constantly shows that a lot of water reaches the foundation, and it doesn't always mean exterior work is needed. Interior drainage with a properly sized pump handles high water volume for many homes. Exterior work comes in when the wall leaks through its face or a footing drain has failed. We inspect inside and outside to decide.
Get a Free Exterior Waterproofing Estimate in Janesville
For a free estimate on exterior waterproofing in Janesville, call 123-456-7890. We'll inspect the wall inside and out and write up a price. You can also reach us here, see our wall repair options, or return to basement waterproofing in Janesville.