A patio that slopes toward the house has sunk next to the foundation, where the soil is loose backfill. That sends rainwater straight at your basement wall. We lift the low side with polyurethane foam until the patio pitches away from the house again, then seal the joint along the wall.
By Rob Diederich, owner · Updated
Typical job
2–4 sections
Time on site
A few hours
Use it
Same day
Warranty
Written warranty
Lifting the house side reverses the slope, so rain runs away from the foundation. Drag the slider.
Why patios tip toward the house
The ground right next to a foundation is backfill from the basement dig. It settles for years after the house is built, and roof runoff keeps soaking it. The patio edge along the house sinks with it, and the whole slab ends up pitched the wrong way.
Settling backfill
The soil pushed back against a new foundation is rarely compacted well. Anything sitting on it settles for years after the house is built.
Fix: Foam fills the voids and stiffens the zone under the slab without adding weight.
Water washout
Roof and downspout water runs into open joints and carries fine soil out from under the slab. The slab drops into the hollow.
Fix: We seal the joints, and point out downspouts that need extending.
Freeze-thaw
Clay-heavy Green Bay soil holds water. Every winter it freezes, swells and thaws softer, loosening the base a little more each year.
Fix: Sealed joints keep water out of the base, which is what freezes.
Why it matters
✓Water that runs toward the house soaks the soil against your basement wall.
✓Ice forms in the low corner every winter.
✓Furniture rocks and doors that open onto the patio start to catch.
How we fix the slope, step by step
1Set a slope away from the houseLevel isn't the goal on a patio. We set a line with a gentle fall away from the house so rain runs to the yard.
2Drill 5/8″ holesPenny-sized holes go through the slab a few feet apart, kept off the edges and corners where concrete is weakest.
3Inject along the house sideFoam goes in along the foundation side first. It fills the void, then lifts that edge so the slab rotates up and the slope reverses.
4Patch and seal along the wallHoles are grouted and the gap between the patio and the foundation is sealed, so water can't run behind the slab and down the wall.
Illustrations, not to scale. Most residential jobs take a few hours, and you can walk on the slab when we pack up.
Why lift the patio instead of replacing it?
Patios usually sit in a finished yard, next to landscaping, a deck or a door. Replacing one means breaking it out by hand or getting a machine into the backyard. Lifting needs a hose run from the truck and a few hours.
Fraction
of what tearing out and pouring new concrete costs
Same day
Walk on it when we pack up, not days later.
No demo
No jackhammers, no dumpster, no torn-up lawn or landscaping.
5/8″ holes
Penny-sized and patched flush. No new slab that won't match.
Stays up
Foam adds almost no weight and doesn't wash out like soil.
Warranty
Written, and spelled out in your quote before you approve it.
Replace
tear out + pour
Demo
Base
Pour
Keep off
Still curing: full strength in about 4 weeks
Lift
foam, one visit
Done in a few hours. Walk on it right away.
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 8
Day 9
Day 10
Replacement timing is typical; a contractor's schedule and the weather can stretch it. New-concrete cure times from Concrete Network.
Your price, without a sales visit
Send three photos and a tape-measure shot. You'll get a firm price by text within 24 hours.
The soil along a foundation is backfill that settles for years after construction, and roof water keeps it wet. The patio edge resting on it sinks, which tips the whole slab toward the house.
Can water from a sunken patio cause basement leaks?
It can contribute. A patio pitched toward the house collects rain and snowmelt against the foundation, which raises the water pressure on the wall. Restoring the slope away from the house is one of the cheapest drainage fixes there is.
Can you lift a patio with a hot tub or pavers on it?
A hot tub needs to be drained and usually moved before lifting, because it adds too much weight and could crack the slab as it rises. Pavers are a different system; foam lifting is for poured concrete slabs.
