Tips on basement foundation cracks

Posted Mar 31, 2021 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 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 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.


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.

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.

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

  • 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.