What causes cracks in basement floor

Posted Mar 31, 2021 in Foundation Crack Repair, Waterproofing

Cracks in basement floor

While every home is unique, they often expe­ri­ence prob­lems that are actu­al­ly very com­mon. One of the com­mon prob­lems is cracks. These cracks can appear any­where, from lit­tle cracks in walls or tiling to major cracks in base­ment floors. As a home­own­er, you need to know what the cause is and, more impor­tant­ly, how crit­i­cal of a prob­lem is it? If you’ve dis­cov­ered a crack in your base­ment floor, learn the pos­si­ble caus­es and how to han­dle them below.

Caus­es of base­ment con­crete cracks

Shrink­age

The two pri­ma­ry parts of con­crete are cement and water. After it’s poured, it cures to become sol­id. As the con­crete dries, it will shrink. The degree of shrink­age is large­ly affect­ed by tem­per­a­ture. If tem­per­a­tures drop while your base­ment cures, that can cause cracks. Like­wise, swel­ter­ing heat will rapid­ly dry your con­crete – and cur­ing too quick­ly also caus­es cracks. Even in per­fect con­di­tions, over time, your base­ment con­crete will expe­ri­ence some degree of shrinkage.

While there are some ways to help mit­i­gate shrink­age, such as con­trolled cracks in spe­cif­ic areas, it’s impos­si­ble to pre­vent them. There are cer­tain areas that are more like­ly to devel­op these cracks than oth­ers, such as around doors or oth­er sharp corners.

On the bright side, cracks in your base­ment floor due to shrink­age rarely result in any struc­tur­al prob­lems. How­ev­er, they still open the doors for oth­er prob­lems like water or pests. That means they should be repaired and sealed when­ev­er you iden­ti­fy them. While you should con­sid­er every crack a poten­tial risk, most cracks under one-eighth of an inch wide aren’t a cause to be concerned.

Set­tle­ment

Anoth­er com­mon cause of cracks in base­ment floors is when the con­crete slab begins to set­tle. Typ­i­cal­ly, set­tle­ment occurs when the soil beneath your foun­da­tion is too unsta­ble to sup­port the weight of your home and it shifts. Most homes are designed to allow for about an inch of soil move­ment – although some areas require the design to allow for up to four inch­es. In addi­tion to soil move­ment, leaks in your base­ment and even tree roots can insti­gate set­tle­ment cracks.

Cracks are one of the most com­mon signs of set­tle­ment. How­ev­er, there are a hand­ful of oth­er signs that might indi­cate an issue with settling:

-Gaps form­ing between the floor and walls

-Gaps form­ing between the walls and ceiling

-Walls pulling away from each other

-Cracks on the walls, espe­cial­ly near corners

If you notice one of these clear signs, make sure to take it seri­ous­ly. You should also look for oth­er signs that can indi­cate the cracks are relat­ed to the set­tle­ment. Doors or win­dows that cease to open cor­rect­ly or floors and sur­faces that notice­ably slope sug­gest your issue could be a seri­ous one. Set­tle­ment is a prob­lem that only gets worse with time. Cracks will con­tin­ue to form and your foun­da­tion could suf­fer con­sid­er­able damage.

Frost heave

Dur­ing the cold­er sea­sons of the year, anoth­er source of cracks in your base­ment floor is frost heave. When soil freezes and thaws, it caus­es an expan­sion than a shift under­neath your foun­da­tion. Like set­tling, this move­ment caus­es your con­crete to also shift and that leads to cracks. The most obvi­ous sign of frost heave are cracks near sup­port columns in the floor­ing. With cold weath­er sea­son around the cor­ner, you should look into ways to help pre­vent frost heave.

Risks of cracks in your base­ment floor

Water seep­age

Any cracks in your base­ment floor open you to the pos­si­bil­i­ty of water seep­age. The ground under­neath your foun­da­tion is full of mois­ture. When there are cracks in your home’s foun­da­tion, it lets pres­sure force the water up into your base­ment. Once a source of mois­ture exists, mold follow.

Struc­tur­al problems

Con­crete base­ments will always crack. For­tu­nate­ly, these small cracks, like those from shrink­age, rarely impact the struc­tur­al integri­ty of your home. How­ev­er, big­ger cracks or those caused by insta­bil­i­ty of the soil beneath your house can lead to seri­ous issues. If you notice sig­nif­i­cant cracks in your base­ment, make sure to have them inspect­ed by a pro­fes­sion­al to iden­ti­fy their dam­age potential.

Inva­sive Pests

There are plen­ty of pests that con­sid­er a crack in the foun­da­tion to be an open invi­ta­tion to your home. While it’s like­ly that you would fix a crack in a wall any­where else in your home, it’s not uncom­mon for cracks in base­ment floors or walls to go unno­ticed. Even if you notice them, you may not con­sid­er them as big of an issue, espe­cial­ly if you don’t fre­quent­ly use your base­ment. In addi­tion to the oth­er poten­tial dam­age caused by cracks, this is a good rea­son to get them fixed as soon as pos­si­ble – oth­er­wise, you might be shar­ing your home with all sorts of critters.

Is fix­ing cracks in the base­ment floor a DIY job?

When it comes to foun­da­tion cracks, there is no one answer. Hair­line cracks and those that clear­ly don’t impact the integri­ty of your home can be sim­ply sealed, or patched and sealed. How­ev­er, if you’re not sure, it’s always bet­ter to be cau­tious and have an expert inspect them. In addi­tion to the poten­tial health risks of mold, mildew, and pests, cracks can be a sign of big­ger prob­lems. If your home is at risk of major dam­age, it’s best to find out as soon as possible.

Pro­tect your home — sched­ule your free estimate

If you’re wor­ried about cracks in your base­ment floor, Fam­i­ly Water­proof­ing Solu­tions can help with a FREE ESTIMATE! We’ll help you find out if your home is at risk for water dam­age and which solu­tions will best serve you.

Con­tact us online to sched­ule an appoint­ment or give us a call at (708) 330‑4466 and sched­ule your inspec­tion today!

Stay con­nect­ed with Fam­i­ly Water­proof­ing Solu­tions on Face­book to learn more base­ment tips and tricks!

About the Author

Maria Kirchner, founder of Family Waterproofing, is a waterproofing expert with extensive hands-on experience in basement waterproofing, concrete raising, and moisture prevention. Passionate about staying ahead through annual training, she shares practical tips on her blog to empower homeowners—like tackling sinking slabs with polyurethane foam for quick, cost-effective fixes. Her customer-first approach has earned hundreds of 5-star reviews, helping families protect their homes with confidence. Connect with Maria for personalised advice: Contact Us.

What our customers say

  • We con­tract­ed Fam­i­ly Water­proof­ing Solu­tions for exte­ri­or wall seal­ing and foun­da­tion crack repair ser­vices. Ken was very thor­ough in explain­ing the work that would be done, and his crew did a great job. This busi­ness was a plea­sure to work with.

    Stacie T.
  • You and your crew did a great job in our base­ment and crawl­space. You went the extra mile to insure that all of our water seep­age prob­lems are over. We would rec­om­mend you high­ly to oth­er peo­ple. Your qual­i­ty and time­ly work out­match­es all the others.

    William
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    Ed
  • Thank you for final­ly get­ting rid of my flood­ing prob­lem. I had almost resigned myself to liv­ing with the Black Lagoon in my base­ment. You were able to iden­ti­fy the real prob­lem with my leak by using some empir­i­cal evi­dence rather than guess­ing and charg­ing me for fan­tas­ti­cal projects. Above all, you talked to me as if l am an intel­li­gent per­son instead of the lit­tle lady” who needs her hus­band to make a deci­sion. Final­ly, the extent and care of your pro­pos­al, with its exten­sive pic­tures, con­vinced me that you are an hon­est bro­ker. My base­ment stayed dry despite the recent tor­ren­tial rains. I would be hap­py to rec­om­mend your work.

    Paris