How to Fix a Cracked Foundation
As many as a quarter of all American homes have damaged foundations, according to the American Society of Civil Engineers. Foundation damage often manifests as cracks that can be more than eyesores; they can actually let water and termites into your home and undermine its structural integrity.
Several factors cause foundation cracks, including natural disasters such as tornados and earthquakes, soil around the foundations that’s too dry or too wet, and improperly compacted soil. While major cracks should be left to the professionals, you should be able to fix minor foundation cracks yourself.
Assess Your Crack
Before you set about fixing your foundation crack, you should assess it to decide whether it’s a job you can tackle.
You should call a structural or civil engineer to fix large cracks and cracks that seem to compromise your home’s foundations. While a single small crack is fixable, numerous small cracks may indicate your foundations are broken. Broken foundations will never regain their strength if they’re simply stuck back together. Consult an engineer for a better solution.
You also shouldn’t attempt fixing a foundation crack that’s likely to widen over time. Shrinkage cracks, caused by shrinking concrete, are a good example of cracks that probably won’t get wider. Often found in basements, they’re usually less than 2 millimeters at their widest point.
Prepare Your Crack
Different foundation cracks suit different repair solutions. No matter what method you’re using, you’ll need to clean the area around the crack.
Lay down a drop sheet to catch any dust and debris that falls from the crack.
A cold chisel and a small sledgehammer can then help you widen your crack, so your repair materials can penetrate it and seal correctly. Take care you don’t widen the crack any more than necessary when you’re working.
If there are loose materials around the crack, use a wire brush to free them. Then vacuum the area and wipe it with a damp cloth. This will remove any dust and debris, which may prevent your sealant or patch from attaching to the concrete.
Repair a Narrow Crack With a Vinyl Concrete Patch
A vinyl concrete patch can easily fix foundation cracks measuring between one-eighth and one-quarter inch wide. These boxed products are available from many home improvement stores.
Mix the patch until it’s a thin, pasty consistency. The instructions might suggest mixing the patch powder with water, but experts insist latex is a better liquid substitute. Latex is more elastic, so it moves better with concrete’s natural tendency to expand in the heat and to shrink in the cold. When you mix your concrete patch with latex, the patched area is unlikely to develop future cracks. The vinyl patch solution will dry quickly, so mix only a small amount of paste at a time.
Spray a mist of water or sponge down the crack; then use a trowel to fill it with the patching paste. Moistening the crack makes sure the concrete doesn’t draw water from the paste, so the patch adheres better and resists cracking. Make sure you pack the paste in tightly to ensure there are no air bubbles between the concrete and the patch solution.
Use the trowel to smooth your finish and remove excess paste. If you’re patching a crack in rough concrete, use a broom to replicate the texture.
Remember, the patch paste dries fast. Wash your bucket, trowel, and any other tools you’ve used quickly, as your cleanup will take much longer if you delay it.
Repair Narrow Cracks Without a Patch Product
While commercial patch products are convenient, they’re not the only way to fix narrow foundation cracks. If you can’t find a vinyl concrete patch, you can make your own from common items sold through home improvement stores.
Mix a solution of one-part Portland cement to three-parts sand. Add concrete bonding agent until you’ve got a mix with a similar consistency to mashed potatoes. Move a small amount of your mix to another bucket and add more bonding agent until the new mix resembles soup. Use a brush to paint the soupy mix into the crack. Then fill the crack with the potato-like mix using a trowel. The trowel can also smooth the surface once the crack is full.
Repair Wide Gaps With Caulk
So long as large gaps, with the width of a quarter inch or more, don’t affect the home’s structural integrity, they can also be fixed with caulk.
You’ll need a flexible caulk to cope with the natural expansion and contractions of concrete. Latex caulk with silicone and polyurethane caulk are both good choices. Simply use a caulk gun to pump the gel-like solution into the crack. The caulk will settle level with the concrete’s surface, so there’s no need to use a trowel for a professional finish.
For the next week, spray the patched surface with water twice daily. This will help the caulk cure and minimize the risk of cracks.
Many people feel homeowners shouldn’t touch large gaps on their own. Unless you’re confident the gap isn’t indicative of a larger problem, consult an engineer.
Repair Deep Cracks with Triple Expanding Foam
Deep cracks can be difficult to fill with caulk and patch paste. Triple expanding foam can get into spaces these other substances struggle to reach. You only need to apply a little foam, as it will quickly expand to fill the space inside the crack. Wait for a few minutes to let the foam expand and dry. Scrape off any excess foam with a trowel to create a flat finished surface.
Paint Over the Crack
No matter what patching method you use, it’s smart to wait a few weeks after your repair job before completing your work. This time allows your repair to dry entirely. Once this time passes, you can paint over your repair to hide the patch job.
The longer you leave foundation cracks, the greater the chance they’ll grow to become major problems. Don’t spend another day staring at that minor foundation cracks. Fixing this common home eyesore is easier than you think.
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