A pool deck or patio that has dropped half an inch at one edge is a trip hazard and a drainage problem, and it is almost never the concrete that failed. The ground underneath moved. Two repairs lift that slab back to grade, mudjacking and polyfoam injection, and both of them work. What separates them is the size of the holes left in the finished surface, how close the equipment has to get to the deck, how much weight goes back into soil that already gave way once, and how many times the deck is likely to need lifting over its life. This post covers how each method works, the names you will see them sold under, when lifting is worth doing at all, and when a slab should be replaced instead.
Why Pool Decks Settle
Concrete sits on whatever was there when it was poured. Around a pool that is often backfill dropped in against the shell and compacted in a hurry, and backfill keeps consolidating for years afterward. Add a downspout discharging at the edge of the slab, a weeping pool line, or the long, saturating Fraser Valley wet season, and fine material washes out from between the coarse particles. A slab loses contact with the ground before it loses elevation, so the empty space that forms under a concrete slab is usually well established by the time anyone notices a lip at a joint. That is why lifting a slab without dealing with the water that emptied the ground beneath it only resets the clock.
Foam Mudjacking, Poly Jacking and Foam Jacking: One Method
The names get mixed up. Mudjacking and slab jacking mean pumping a cement slurry under the slab. Foam mudjacking, foam jacking, poly jacking and polyurethane lifting all describe the same thing: injecting expanding polyurethane foam. When you compare quotes, ask what material is going under the slab, because two contractors using different words may be offering the same repair, or two very different ones under similar names.
How Each Method Lifts a Slab
Mudjacking pumps a cement and sand slurry through holes drilled in the concrete. The slurry fills the void, and as more of it arrives the pressure raises the slab. It is a mature method and it lifts heavy concrete reliably.
Polyfoam injection pumps a two-part polyurethane through much smaller ports. The two parts react under the slab, expanding to fill the void and then pressing upward as expansion continues. The lift is controlled by how much material goes in and at which port, and the foam reaches about 90 percent of its strength within fifteen minutes. Most residential slab lifts are finished in a few hours. We go further into the material itself in what polyfoam grout is and how we use it to restore concrete.
Hole Size and Surface Patching
Slurry is thick, so mudjacking needs larger holes, and usually more of them across the slab. Those holes get patched with fresh concrete, and fresh concrete does not match a deck that has spent years in the sun. The result is a grid of pale circles. On a plain grey utility slab that is tolerable. On stamped, tinted or exposed aggregate concrete it is the thing the owner notices every time they walk outside.
A small port can be placed in a joint or inside the texture of an aggregate finish, then patched so it is hard to find.
Equipment Access and Landscaping
Slurry is heavy and cannot be pushed far down a hose without losing pressure, so the pump has to come close to the work. In a fenced backyard that usually means pulling fence panels and running equipment across the lawn, over the irrigation lines and around the planting. Polyurethane moves through more than 300 feet of slender hose, so the rig stays on the street or the driveway and only the hose comes through the gate. On a finished backyard that difference often matters more to the owner than anything happening under the slab.
Weight Added to Weak Soil
When a slab sank because the soil below could not carry what was already on it, packing in a thick layer of heavy material works against the diagnosis. That matters on a deck taking splash-out from the pool and standing rain for half the year. It also expands into the loose soil around the void instead of forming one dense pad under the concrete.
Cost Against Service Life
Whether it turns out cheaper depends on the site. Where drainage has been corrected and the ground is stable, a mudjacked slab can sit for a long time. The honest comparison is the quote against how many times the deck is likely to need lifting, not the quote alone.
When Mudjacking Still Makes Sense
We do not offer mudjacking, but it is the right call often enough to say so plainly. A shed pad, a utility slab, or a rough section of driveway where appearance does not matter, access is open, and the soil below is dry and stable does not need polyfoam. What pushes a pool deck the other way is a decorative finish, tight backyard access and constant water together. Those three conditions describe most residential pool decks and patios, which is why we recommend polyfoam for most of them.
Other Options and Whether Lifting Is Worth Doing
Lifting is not the only answer. The alternatives are tearing out and repouring the slab, or living with it and grinding down the trip edges. Lifting is worth doing when the concrete itself is sound and the problem is the ground. It is not worth doing when the slab is shattered into small pieces or the rebar has snapped or badly corroded. In those cases the concrete has failed along with the soil, and replacement is the honest answer. Either way, the water source comes first. Downspouts, grading and pool overflow should be dealt with alongside the injection, as covered in our Fraser Valley drainage and foundation check, and in why the order of repairs matters.
Frequently Asked Questions
Is foam mudjacking the same as mudjacking?
No. Foam mudjacking is a common name for polyurethane foam lifting, also sold as poly jacking or foam jacking. Traditional mudjacking uses a cement slurry. Same goal, different material, different holes and a very different weight left under the slab.
How soon can we use the pool deck after the repair?
Mudjacking uses a cement fill that needs a day or more of curing before the slab takes weight, depending on the weather.
Will the injection holes be visible when the work is finished?
Polyfoam ports are small, and on a textured or stamped surface they are usually hard to pick out once patched. Mudjacking holes are larger and patched with concrete, so they tend to stay visible as lighter circles. Neither method is truly invisible on a smooth, evenly tinted slab, and it is better to agree on that before the work starts.
Can a cracked slab be lifted, or does it have to be replaced?
Cracked concrete can often be lifted, as long as the pieces are big enough to move as units and the reinforcement is intact. Injection points are planned so each section rises together. A slab that is shattered, or has snapped or badly corroded rebar, is not a candidate and should be replaced.
Is polyurethane foam safe to use next to a swimming pool?
Once cured, the foam is chemically inert. The real concerns near a pool are mechanical.
How long should the repair last?
A lift paired with corrected drainage should hold for decades. A lift on its own, with the downspout still discharging at the slab edge, is a temporary fix no matter which material goes in.
Sunken concrete around a pool or patio is worth looking at before it becomes a trip hazard or starts sending water back toward the house. If a slab on your property in Chilliwack, Abbotsford, Langley or elsewhere in the Fraser Valley has dropped, book a free estimate with Black Birch Contracting. We will look at what moved underneath it and recommend the repair that suits the finish, the access and the soil.