What to do when you find a crack in your foundation

Posted Jul 01, 2024 in Foundation Crack Repair, Waterproofing

The foun­da­tion walls and floor of your base­ment are built to sup­port your house and to keep out the mois­ture that sur­rounds them. Their pur­pose is to keep your home dry and cre­ate a sta­ble struc­ture for you and your fam­i­ly. When foun­da­tion walls crack, it can cause mois­ture or harm­ful gas­es from the ground to seep into your base­ment, decreas­ing the air qual­i­ty, caus­ing mold growth and dam­ag­ing per­son­al property.

There is no viable quick fix when it comes to base­ment foun­da­tion crack repair. There are dif­fer­ent cor­rec­tion meth­ods and knowl­edge need­ed to fix them cor­rect­ly. Let’s take a look at the list below for some tips and a lit­tle more knowl­edge about foun­da­tion cracks.

Exterior crack

1. There are three rea­sons for cracks in your base­ment foundation:

Shrink­age:

Shrink­age is caused by the poured con­crete, walls or floor, dry­ing too fast. The quick-dry­ing time caus­es the con­crete to shrink, and hair­line cracks are the result. Shrink­age is notice­able not long after the con­struc­tion of the house.

Set­tling:

Set­tling caus­es cracks in the base­ment foun­da­tion when the ground below the foun­da­tion con­tin­ues to com­press under the weight of the poured con­crete. The cracks that hap­pen are a result of set­tling and direct­ly relat­ed to the amount of ground com­pres­sion. If the ground under the base­ment foun­da­tion only com­press­es for a short time, the cracks are gen­er­al­ly minor. How­ev­er, if the ground con­tin­ues to set­tle for a more extend­ed peri­od, the cracks can become more numer­ous and troublesome.

Move­ment:

The most com­mon cause of base­ment foun­da­tion cracks is move­ment. Move­ment and shift­ing in the ground under the foun­da­tion can cause foun­da­tion cracks. As with set­tling, if the move­ment con­tin­ues, the cracks will get worse.

2. Cracks in foun­da­tion walls and floors hap­pen for the same rea­sons, but are not the same when it comes to fix­ing them

Cracks in the base­ment foun­da­tion floor can be more chal­leng­ing to fix, espe­cial­ly if you are notic­ing leak­ing or wet­ness. Typ­i­cal­ly, the floor cracks will only leak when there is a sig­nif­i­cant amount of water leak­ing under­neath your base­ment floor.

If you are notic­ing leak­ing on your foun­da­tion floor, it would be a good idea to check your sump pump. Often, when you see water com­ing through the cracks in the base­ment foun­da­tion floor, the sump pump has stopped work­ing as it should. If your sump pump is work­ing, then an under­ground drainage sys­tem could solve your floor leak­age issues.

When water leaks are not­ed, base­ment foun­da­tion crack repair becomes very dif­fi­cult. Wet con­crete will not allow water­proof­ing prod­ucts to adhere well or per­ma­nent­ly. Also, for the best seal, the prod­uct would have to be applied to the top and under­side of the floor which would be very dif­fi­cult at best.

3. Base­ment foun­da­tion cracks can neg­a­tive­ly affect the air qual­i­ty in your basement

Though water leak­age, through foun­da­tion cracks, can be a big has­sle, cracks in base­ment foun­da­tion walls and floors could be an entry for oth­er poten­tial­ly dan­ger­ous gas­es, such as Radon, Methane, and even pesticides.

When the cracks give these gas­es a pos­si­ble entry into your base­ment, the air qual­i­ty in your base­ment could become a prob­lem for you and your family.

Basement foundation mold

4. Mold

Base­ment foun­da­tion walls that have water leaks can poten­tial­ly cause a mold infes­ta­tion in your base­ment due to the exces­sive mois­ture that can soak into the con­crete. Mold can slow­ly spread through­out oth­er areas of your home.

At a glance, mold on your walls is unpleas­ant to look at and could cause a nasty smell as well. How­ev­er, the poten­tial health risks and struc­tur­al risks to your fam­i­ly and home could be a lot more dan­ger­ous. Mold not only destroys the mate­r­i­al it col­o­nizes on, but it can also adverse­ly change the air qual­i­ty that in turn could cause illness.

5. Dif­fer­ent types of base­ment foun­da­tions require dif­fer­ent types of repair for opti­mal results

  • Poured con­crete: Poured con­crete walls are sta­ble and formed as a sol­id block of con­crete. If you need to repair cracks in this type of struc­ture, an expand­ing ure­thane-based sealant can be inject­ed into the cracks to seal them.
  • Block, Brick or Stone: Walls made out of these mate­ri­als are made up of mul­ti­ple parts patched togeth­er with cement or mor­tar. Repair­ing cracks in these types of struc­tures is best done from the out­side rather than the inside of the base­ment. A flex­i­ble elas­tomer­ic mem­brane is a pre­ferred mate­r­i­al for this type of base­ment foun­da­tion crack repair.

6. Epoxy for base­ment foun­da­tion repair

Epoxy is a sub­stance that can be used to fix cracks in poured con­crete base­ment foun­da­tion struc­tures. Using epoxy for crack repair may not stop the wall from crack­ing or leak­ing again in the future if there is a con­tin­ued prob­lem with the ground pres­sure push­ing against the walls. How­ev­er, this could be a quick-fix option until fur­ther inves­ti­ga­tion is done on your foundation.

Interior crack
Exterior crack

7. Repair­ing pre­vi­ous­ly repaired cracks

It is vital that pre­vi­ous­ly repaired cracks are repaired cor­rect­ly as they are dif­fer­ent than a new crack and require addi­tion­al prepa­ra­tion and knowl­edge when select­ing a method of repair that will be effective.

Tak­ing the time to remove as much of the pre­vi­ous repair medi­um as pos­si­ble, and inject­ing the crack with ure­thane on the inside of the struc­ture, is a suit­able method.

A pre­vi­ous­ly repaired crack can also be cor­rect­ed from the out­side using either the elas­tomer­ic mem­brane or sodi­um ben­tonite as the pre­ferred repair medium.

8. Don’t just fix the leak­ing cracks, fix them all

If you have mul­ti­ple cracks in your walls but are only seek­ing crack repair for the ones that are leak­ing, the oth­er cracks will even­tu­al­ly leak if you don’t fix the source of the accu­mu­lat­ed water.

Water fol­lows the path of least resis­tance and the cracks that weren’t leak­ing before become the new door­way for the built-up water to escape.

It is more cost-effec­tive to have all your base­ment foun­da­tion crack repairs done at the same time rather than hav­ing some­one come out mul­ti­ple times to fix the oth­er cracks as they start to leak.

Base­ment foun­da­tion crack repair is a nec­es­sary invest­ment to pro­tect your home and your fam­i­ly from poten­tial prob­lems asso­ci­at­ed with the cracks. Whether it be struc­tur­al insta­bil­i­ty or poten­tial health risks, it is essen­tial to have base­ment foun­da­tion cracks repaired quick­ly and correctly.

Many prob­lems can be pre­vent­ed by tak­ing sim­ple pre­cau­tions while oth­ers may require a more com­pli­cat­ed approach. If you are expe­ri­enc­ing dif­fi­cul­ty resolv­ing a foun­da­tion, base­ment, crawl­space or a drainage issue, con­tact your friends at Fam­i­ly Water­proof­ing Solu­tions today (708) 330‑4466.

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.

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