Denver Foam Concrete Leveling

A settled slab is rarely a concrete failure. Break one out and the concrete itself is often perfectly good. What's missing is the four to six inches of support that used to sit under it: base washed sideways by a downspout, trench backfill that finished compacting a decade after the pour, soil that shrank away during a dry stretch and never came back. The slab didn't sink. The ground left.

Polyurethane leveling goes after that directly. We drill a small port, inject a two-part resin that expands into every corner of the empty space, and the slab rides back up on the fill. It hardens in minutes and it weighs almost nothing, which counts for a lot when the soil that already failed once is the same soil holding everything now.

What's actually under a settled Denver slab

What sits under Denver flatwork, block by block

Older neighborhoods surprise people. Pull a century-old walk in Wash Park or Park Hill and there's frequently no base course at all, just concrete laid on native soil that was scraped flat and called good. It held because the concrete was thick and the soil stayed dry. Change the moisture, and the whole equation moves.

Scrape-and-rebuild lots in Sloan's Lake, Berkeley, and the Highlands have the opposite issue. There's imported fill under everything, sometimes deep, and if it went in fast it's still finding its level. Central Park flatwork sits on engineered fill that's usually solid, which is why the calls from there tend to be about one apron or one strip along a garage rather than a whole yard. And in University Hills, half of what we chase is irrigation. A leaking zone under a walk will hollow it out quietly for a couple of seasons.

What we look at before a single hole gets drilled

• Where roof water lands, not where the gutter says it should
• Sprinkler zones and heads near the settled panel
• Whether the slab tips toward the house or away from it
• Joint condition, since open joints feed water into the void
• Slab thickness, checked with a test port before we commit to a pattern
• Crack pattern, which tells us how many pieces we're lifting
• What sits on top: rails, condenser units, steps, planters

Foam and slurry are not the same tool

People use the words interchangeably. They shouldn't. Mudjacking pumps a sand and cement slurry through holes a little over an inch and a half wide, and it puts real weight back under your concrete. Foam goes in through a port the size of a pencil, expands as a closed-cell polyurethane, and adds a few pounds per cubic foot. It's water resistant, so it won't wash out the way loose fill can.

So which one? Slurry is the value pick on firm subgrade with a big void to fill, and we run plenty of it. Foam wins when the soil is soft and can't take more load, when the panel butts a foundation and needs a gentle push, when the void is thin and irregular, or when you need the surface back in service within the hour. That's the whole decision. Not brand loyalty, just what the ground can carry.

Timing, and the homework that's yours

Injection has a longer season than most concrete work. The resin cures by chemical reaction, not by ambient warmth, so a cold clear day is workable. Frozen subgrade is still a wall: lift a slab that's frost-locked to the ground and you tear it. We watch for thawed ground more than the thermometer, and a January warm run is often a fine week to level a walk.

Then the part we can't do for you. Get roof water away from the concrete. Downspout extensions, a corrected splash zone, a regraded strip along the walk. Seal the joints so surface water quits pouring into the space we just filled. We lift the slab; you keep the water off it. Do both and the repair holds for a long, boring stretch of years.