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


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.


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!

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What our customers say

  • 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.

  • 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.
  • Work­man­ship and ser­vice were excel­lent. Would rec­om­mend with­out reservation.