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Basement Crack Repair - 6 Things You Need To Know

Dec 8, 2016 • By Matthew Stock with Mike Likvan.


Your foundation walls are designed to support the weight of your house and to resist moisture that’s surrounding them.  When foundations work, you get to live in a stable and dry environment.  When they crack, moisture seeps into your basement; it damages valuables like carpeting, keepsakes, and furniture; it promotes mold growth and it disrupts your peace of mind.

Fixing foundation cracks isn’t as simple as squirting epoxy into them. There are different types of cracks and foundations, as well as very specific ways to properly do basement crack repair for each of them.  If you’re noticing wall cracks in your basement and want to get them fixed, below are some things you need to know before you hire someone to repair them.

6 Things You Need To Know About Basement Crack Repair

1) There are 3 basic causes of cracks in foundation walls.

  • Shrinkage – This happens shortly after a house is built.  The poured concrete foundation dries too quickly, shrinks and hairline cracks appear. 
  • Settling – Typically this happens for only a short period after the house is built.  The foundation is placed onto ground that still wants to compress.  If the compression is minor, the cracks usually are also.  However, if the ground continues to compress for a while, the existing foundation cracks get progressively wider and new ones may appear.
  • Movement – This is the most common cause of cracks we see.  When the ground around the foundation moves and shifts it causes cracks.  As movement continues these cracks worsen and multiply. 

2) Cracks in basement floors may happen for the same reasons as above, but they are different than walls cracks.  Floor cracks typically don’t leak unless an excessive amount of water is accumulating under your basement floor. If you have this problem, consider installing a below floor drainage system.  Before you do that though, make sure you check your sump pump.  Many times water coming through the cracks in the floor is a sign your sump pump has stopped working properly.

Sealing basement floor cracks is difficult, if not impossible.  Any waterproofing product you try to stick to the surface of the floor will eventually fail because the constant wetness of the concrete will keep it from adhering well or permanently. The problem is that the best topical crack repair is one applied on the side of the concrete where the water first enters.  Unfortunately, in the case of basement floor cracks, the water is entering from the underside that you can’t reach. 

3) Crack repair methods also depend on the type of foundation that’s breaking.  Cracks in a poured concrete foundation can be filled with a flexible, expanding urethane sealant using an injection method because these walls are solid and monolithic. Cracks in block, brick or stone cannot be injected because those walls are made up of many pieces, much like a puzzle, that are held together with mortar which is porous.  Cracks in these foundations are best repaired from the outside using a flexible, trowel-on elastomeric membrane. If outside repairs aren’t practical or affordable, then a tear resistant liner can be installed inside to protect your basement from moisture seeping in. An under-floor drainage system also needs to be installed so the moisture that accumulates behind the liner has somewhere to drain.

4) Epoxy can fix poured concrete foundations, but if ground pressure pushes against the foundation walls after the repair, the epoxy will not keep the wall from cracking again and leaking.  With ground pressure being a year round occurrence in Chicagoland there are some sealing methods that are more reliable.  We did a blog article worth reading regarding epoxy vs. urethane injection

5) Previously repaired cracks present a unique repair challenge and require additional preparation work and know-how to select an effective method to seal them again.  The best options are to clean off as much of the previous repair as possible and inject it with urethane, or go outside and seal it with either sodium bentonite or elastomeric membrane.

6) All cracks eventually leak.  Fixing only the leaking ones just delays the inevitable, and costs more because you have to pay more than once to bring the repairman out.  Water seeks the path of least resistance. If there are multiple cracks some will provide less resistance to the water than others so they leak first.  Once the cracks are sealed, the water will look for the next easiest path which is typically the cracks that weren’t previously leaking. When you are having cracks repaired, take advantage of quantity discounts usually available and have them all fixed at once. 

U.S. Waterproofing knows the most reliable methods to repair cracks so then can be fixed and forgotten.  We’ve fixed hundreds of thousands of cracks since 1957.  When cracks and moisture threaten your quality of life you can schedule a no-charge visit from one of our Advisors.

Tags: basement waterproofing facts, foundation cracks, basement waterproofing solutions, foundation repairs

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