How To Repair Foundation Cracks From Inside

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Foundation cracks are a mutual occurrence, peculiarly in older homes. Fortunately, repairing a thin crack is commonly a simple weekend project. For hairline cracks in and around your foundation, the quickest fix is urethane caulk. While caulking is fast and easy, it's not the best solution for wide or deep foundation cracks. For cracks between ⁱ⁄₁₆ and ¹⁄_four in (0.16 and 0.64 cm), go with a physical injection kit. If the crack is wider than ⁱ⁄₄ in (0.64 cm) or runs horizontally through a foundation wall, call a structural engineer.

1
Seal thin, non-structural cracks with urethane caulk. While it's the easiest method, caulking is commonly a surface-level, temporary fix. Caulking is best for cracks in joints between a foundation and physical surfaces, such as a driveway or sidewalk. It'due south also suitable for shallow hairline cracks in basement floors and non-load bearing walls.^[1]
- Find urethane physical caulk online or at hardware and dwelling improvement stores.
- Go with urethane caulk if you're confident the fissure doesn't run deeply through your foundation wall or slab. Caulk tin can't penetrate the interior of a deep crack; a concrete injection kit is the mode to go if the cleft is more than 2 or 3 in (5.1 or 7.6 cm) deep.
Warning: Cracks that are ^one⁄₄ in (0.64 cm) or wider, horizontal cracks, and basement walls that bulge inward are signs of structural problems. Consult a structural engineer for these issues. Look online or ask a local contractor for a referral.^[2]
2
Scrub off any loose concrete, paint, or old filler. Dislodge loose debris around the cleft with a wire castor to make the surface more receptive to the caulk. If necessary, knock off thick deposits of mortar, physical, or old repair compound with a small hammer and chisel.^[3]
- After scrubbing the surface, sweep or vacuum any remaining dust and droppings. Lingering grit will prevent the caulk from bonding with the concrete.
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iii
Use a caulk gun to fill the crevice with the urethane chemical compound. Load the caulk cartridge into the cradle of a caulk gun, then snip about ¹⁄_eight in (0.32 cm) off of the tip. Squeeze the trigger and slowly run a bead of caulk into the crack.^[four]
- Intermission periodically so the compound tin can seep into the crack as deeply every bit possible.
- Wear piece of work gloves when working with urethane caulk. If you go any on your pare, promptly wipe it off with a cloth dipped in paint thinner or mineral spirits.
4
Level the caulked surface, then allow it to cure for 4 to 6 hours. Run a ane ¹⁄₂ in (3.viii cm) putty knife over the filled fissure to smooth the surface and scrape abroad backlog caulk. Level the compound with the surrounding surface, then permit information technology cure for at least 4 to half dozen hours, or according to the manufacturer's instructions.^[5]
- Wipe your putty knife with mineral spirits as soon as you've finished using information technology.
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ane
Go with an epoxy or polyurethane injection kit for a longer lasting fix. Buy a kit that includes a 2-part epoxy sealer, caulk-type cartridges of repair compound, and injection ports, which are pocket-sized plastic nozzles that allow you to fill the within of the crack. You'll adhere the ports to the wall, embrace the crack's surface with the 2-office epoxy sealer, then inject the crack with the repair compound.^[6]
- In that location are 2 types of injection compounds available. Epoxy is the preferred option for dry cracks in load begetting foundation walls and slabs. Since epoxy can't bond to wet surfaces, polyurethane is best for cracks that are actively leaking.The awarding process is basically the same for both compounds.^[vii]
- Experience around the crack to exam for dampness. If information technology feels at all clammy, dry it thoroughly with a blow dryer, then check it once more after 15 minutes. If it'southward still dry, go with epoxy; if information technology'southward wet and won't dry out, inject it with polyurethane.
2
Scrub and sweep the area effectually the cleft. To gear up the surface for repair, remove loose concrete, paint, and former sealer with a wire castor. Then sweep or vacuum up whatever lingering dust and droppings.^[8]
- If you lot're repairing a crack in a foundation wall, lay a driblet cloth beneath the work expanse to protect your floors from drips of repair compound.
3
Tap 10d nails halfway into the crack in 12 in (30 cm) intervals. Gently hammer 3 in (7.6 cm) 10d finishing (headless) nails into the crack. They'll help you lot line upward the injection ports' nozzles with the cleft. You lot'll eventually remove the nails after you've slid the injection ports over them.^[ix]
- Leave enough of each blast's shaft exposed so about ^ane⁄₂ to 1 in (1.3 to 2.5 cm) will beetle by the port's nozzle. That way, yous'll be able to grasp the extra length to remove the boom.
- In a pinch, apply pins, toothpicks, or thin java stirrers instead of nails to marshal the ports with the crack.
4
Slide the plastic injection ports over the nails. Scoop smalls amounts of each epoxy part onto a slice of scrap forest, then mix them until they're a uniform gray color. Dab the base of operations of a port with a minor corporeality of epoxy, slide the port over a finishing boom, and press the epoxy-covered base against the foundation surface. Repeat the steps to install the remaining injection ports.^[10]
- Make certain you lot don't cover the injection port'south hole with epoxy. Don't use so much epoxy that information technology'll spread and clog the hole when you press the port confronting the wall.
- When mixed together, the two parts form a compound that will cure and harden. Use split up sticks to scoop out the two parts to avoid contaminating the containers.
v
Remove the nails after installing the ports. Hold the base of operations of the port confronting the wall with one hand. With the other, pinch the length of the nail that protrudes by the port's nozzle, and so pull the nail straight out of the wall.^[11]
- Keep removing the remaining nails before injecting epoxy into the ports.
6
Spread the ii-role epoxy over the crack and injection ports' bases. Mix together the ii-part epoxy, and spread it over the cleft with a trowel or putty pocketknife. Cover the scissure and the injector port bases with a ¹⁄_eight in (0.32 cm) thick layer, and spread the compound almost one in (2.5 cm) on either side of the scissure. Let the layer to cure for half dozen to 10 hours, or according to the kit's instructions.^[12]
- Check your product's instructions for the amount of 2-part epoxy needed to cover the fissure'south surface area. Scoop out the recommended amounts of each part of epoxy with separate sticks, then mix them together on a piece of scrap wood with a clean putty knife.
- Wipe your putty knife with a rag and mineral spirits or paint thinner as soon as you've finished spreading the epoxy over the fissure. The compound will be tough to remove once it has cured.
seven
Make full the lowest port until repair compound oozes out of the i above information technology. Fit the cartridge of repair compound into a caulk gun, then snip about ⁱ⁄₈ in (0.32 cm) off of the tip. Insert the cartridge tip into the lowest port'south nozzle, and squeeze the caulk gun'due south trigger. Keep squeezing the trigger until the chemical compound starts seeping out of the port directly above the ane you're filling.^[thirteen]
- Employ gentle force per unit area to command the flow equally much as possible. Cease squeezing as soon as the compound starts oozing out of the port to a higher place the one you're filling. If too much seeps out, excess epoxy could drip onto the walls.
8
Plug the nozzle, then proceed filling each injection port. After injecting the first nozzle, plug it with one of the plastic caps that came with the injection port kit. Then insert the cartridge tip into the adjacent port above the first, and inject it with the compound.^[14]
- Finish squeezing the caulk gun's trigger when the compound oozes out of the port higher up the 1 you're injecting. Repeat the steps until you lot've injected compound into each of the ports.
9

Allow the repair compound to cure, then cutting off the injection ports. Later on you've injected and capped each port, allow the compound cure according to your product's instructions. Polyurethane cures inside minutes or hours, while epoxy may have up to 5 days. Finally, using a hacksaw, cut off the necks of the injection ports where they meet the foundation wall.^[fifteen]

Tip: To disguise your work and ensure the crack is sealed, mix a bit of 2-part epoxy compound and patch the spots where you sawed off the ports' necks.

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As soon equally you spot foundation cracks, repair them or consult a professional person. Putting the project off will brand matters worse.^[16]
Choose a liquid physical repair kit that includes an epoxy chemical compound labeled for your crack's width. Thinner cracks require a less viscous compound, while a more than viscous sealer works better for wider cracks.
If foundation cracks or h2o harm are ongoing problems, talk to a structural engineer or landscaping builder near long-term solutions, such equally cleaning or repairing your gutters, installing an hole-and-corner drainage organisation, and regrading your property.^[17]
Termites tin can enter foundation cracks as tiny as ¹⁄₆₄ in (0.forty mm) wide. After sealing the crack, take a licensed termite command professional check for signs of infestation.^[xviii]

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Think that horizontal or wide cracks and basement foundation walls that bulge inward are signs of structural problems. Consult a professional instead of attempting to resolve these issues on your own.^[nineteen]
Cured epoxy resin and urethane caulk are hard to remove, then protect surrounding surfaces and wear thick disposable gloves while repairing the crack in your foundation.^[20]

Things You'll Need

Wire brush
Broom or Shop vac
Work gloves
Urethane concrete caulk
Caulk gun
ane ¹⁄_ii in (3.viii cm) putty knife
Chisel (optional)

Wire castor
Broom or Shop vac
Epoxy or polyurethane concrete injection repair kit
3 in (7.6 cm) 10d finishing nails
Hammer
Work gloves
one ¹⁄_ii in (3.viii cm) putty knife
Caulk gun
Hacksaw
Accident dryer (optional)
Chisel (optional)

About This Article

Article Summary X

To fix a hairline foundation crack, apply urethane caulk using a caulk gun. As y'all utilise the caulk, pause occasionally to let it seep into the fissure. If y'all believe the crevice is deeper than 3 inches, utilise an epoxy or polyurethane concrete injection kit to exercise the repair. Earlier using the kit, scrub away any quondam pigment or other debris using a wire brush. Once you've cleaned the area, gently hammer 10d headless finishing nails into the crack and then y'all can line up the injection ports. So, slide the ports over the nails, remove the nails, and spread the compound over the scissure. Y'all should also inject the compound into all of the ports, seal them, and go out the compound to cure. Recall that if you notice a fissure that'southward wider than 1/iv inch, or runs horizontally, call an engineer, since cracks like these bespeak structural problems. For tips on how to disguise your physical injection repair, keep reading!

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