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Why is my concrete sinking?

Posted Mar 17, 2021 in Concrete Raising

What caused your con­crete slab to sink? (The con­crete we are refer­ring to include side­walks, dri­ve­ways, patio slabs, pool decks, and even some home foun­da­tions.) Most con­crete slabs are free-float­ing which means they rest on the soil beneath them. If you take away soil, your slab will move. It’s that sim­ple. Fam­i­ly Water­proof­ing Solu­tions can raise, lev­el and sta­bi­lize your sunken con­crete; how­ev­er, we feel it is impor­tant for you to under­stand what caus­es these issues. Here are the 2 major rea­sons why your con­crete slab can sink:

Nat­ur­al char­ac­ter­is­tics of soil

If you were to con­duct a soil test around the Greater Chicagoland area and sur­round­ing town­ships, you would be amazed by the vary­ing com­po­si­tions of our soils. These com­po­si­tions will bear dif­fer­ent load capac­i­ties, set­tle and com­pact dif­fer­ent­ly, and expand/​shrink in wet or dry cli­mates. With the right soil com­po­si­tion and prepa­ra­tion, you will have very lit­tle prob­lems with uneven, sunken con­crete slabs. Here are a few things to remember:

1. Soils will nat­u­ral­ly com­pact and set­tle over time. Prop­er soil type and com­paction are required to sup­port con­crete slabs. Many slabs require bring­ing in select fill soil as a base. The prop­er thickness/​amount is often deter­mined by a com­pa­ny that con­ducts a soil bor­ing test.
2. Soils that con­tain large amounts of clay will shrink and expand dur­ing dry/​wet cli­mates. This move­ment will cause your con­crete slabs to become uneven over time. Prop­er drainage and irri­ga­tion can help con­trol huge move­ments of your con­crete slabs.

Soil washout

The soil under­neath your side­walk, dri­ve­way, patio slabs and oth­er con­crete sur­faces offer sup­port and sta­bi­liza­tion. Water can wash away soil; fur­ther­more, this will cause voids under­neath your con­crete slabs. Over time, your con­crete will begin to sink or even crack due to the lack of sup­port. Here are a few main rea­sons why this happens:

1. Home gut­ters wash­ing out the soil under­neath dri­ve­ways and sidewalks
2. Nat­ur­al drainage routes water under­neath dri­ve­ways and side­walks (drainage between hous­es rout­ed to the street will usu­al­ly cross a sidewalk)
3. Con­crete expan­sion joints rot­ting away and not being replaced caus­es water to wash away soil
4. Weed eaters caus­ing deep canals around your dri­ve­ways and side­walks (eas­i­ly fixed by adding soil or sand every year

Get a free con­crete lift­ing estimate

Fam­i­ly Water­proof­ing Solu­tions can raise, lev­el, and sta­bi­lize your con­crete slabs for an afford­able price. One of the biggest advan­tages of using polyurethane foam is that it fills the voids while also adding sta­bil­i­ty. On top of that, it’s water­proof. Call our team at (708) 330‑4466 for more infor­ma­tion or to get a FREE esti­mate.