How to fix Foundation Cracks? What you should Know
This article covers the most common fundamental concrete foundation problems with cracking, leaking basement foundations, and what is required to solve various issues or at least the basic knowledge of what you as a building owner should understand even if you are hiring professionals. Before you can decide on a repair solution for a foundation crack, you need to identify what type of foundation you have. You may have a poured concrete foundation, or an ICF poured concrete foundation, or a concrete cinder block construction.
Types of Concrete Building Foundations:
The Common Standard type is solid concrete poured walls that sit on a concrete footing with various rebar amounts within, and usually, a concrete floor poured up against it.
How to Repair Poured Concrete Foundation Cracks.
There are several ways to repair foundation cracks, and depending on the size of the crack width determines which method you should use. Let's start with what not to do and why! Do not use any product like hydraulic cement, tar, silicone, or any miracle leak stop. They are only surface repairs that might feel like you have solved the problem but will only delay a proper, often more costly repair at a later time. Patches tend to trap water inside the wall, where it can do more damage. Owners should only use these patching methods in an emergency or quick effort to stop flooding. Poured foundation walls only have these approved options for repairing leaking non-structural cracks, vertical or diagonal cracks less than ¼ inch wide.
1. Polyurethane or Epoxy crack injection. 2. Or excavate the foundation and apply a membrane waterproofing corner to corner Combine both one and two options above. For membrane installation in areas of the country with frost, it must wrap around a corner to prevent freeze and thaw action pushing the membrane off over time.
Polyurethane Foundation repair
Most basement cracks that cause water or moisture problems are non-structural. Anyone can effectively repair these types of foundation cracks from the inside without excavating by using low-pressure polyurethane crack injection. It is a simple process by installing surface injection ports with an Epoxy paste every 8-10 inches apart along the crack’s total length. The Epoxy Paste is then used to cover the whole crack length before injection. Once the epoxy paste is cured, using a cartridge or a product with similar packaging, start injecting the polyurethane at the bottom of the crack. Fill until it exits the next injection port, and repeat until reaching the top of the wall. Polyurethane injection chemically reacts with moisture and expands through the wall to the exterior and even fills the voids along the way. This repair method creates a permanent seal like a gasket the should last the life of the foundation.
Epoxy Foundation Repair
Epoxy crack injection is used for structural repairs when a concrete wall has cracks larger than ¼ inch, or if portions of the foundation wall have shifted, leaned, bowed, or has horizontal cracks. The low-pressure crack injection process of a polyurethane injection or an epoxy injection is similar. Epoxy effectively bonds the wall back together. An Epoxy injection also will fill the crack through the wall to the outside but may require selecting the correct viscosity (thickness) for the repair. Epoxy crack injections can effectively repair a leaking or a non-leaking crack.
The choice usually comes down to cost because Epoxy will cost more than polyurethane because of the volume required to complete the repair. But you must inject epoxy if the cracking is considered structural. For some structural repairs, using epoxy alone may not be enough to prevent re-cracking in the long term. In such cases, you can use carbon fiber reinforcement straps, or fabric, or stitches, aka staples, with the epoxy to reinforce the foundation wall. These days carbon fiber has been replacing steel reinforcement as the standard reinforcement method; however, not to say steel does have its specific use but can cost much more without the additional benefit.
High-pressure crack injection
How is high-pressure crack injection done?
High-pressure crack injection is usually only used on very fine cracks that are actively leaking or previously incorrectly repaired foundation cracks, making it challenging to find the fracture in the wall. The repair method is straightforward.
Holes are hammer drilled at 45 degrees, every 6 inches at approximately 5 inches deep, alternating each side of the crack to intersect the crack inside the wall. You then insert a special hollow bolt with rubber nuts that can compress tight (called a Packer).
A unique high-pressure polyurethane is generally used with a modified grease tool or a single component high-pressure pump to inject these problem cracks with pressures up to 3000-6000psi. This repair method is a last resort or least preferred as drilling into the concrete may be considered destructive to the concrete wall. But this method is a quick and effective method for actively leaking situations.See our High-Pressure kit
How do you Repair ICF Foundations?
Insulated Concrete Form poured walls
Insulated Concrete Form poured walls are different from the standard poured concrete walls because the concrete forms for ICF foundations are built from a polystyrene foam that stays in place after the concrete has cured, acting as the basement foundation insulation. You can often see if you have an ICF foundation in the unfinished outside wall of utility rooms.
Insulated concrete form basements can leak, but a little harder to diagnose a leak problem as the concrete wall is covered with foam, hiding any possible crack or flaw. When built, these foundations should have an exterior membrane or dimple panel drain installed, but that is not always the case. Owners will need to remove some of the foam at the leak site and follow the water to discover its source. In most cases, low-pressure polyurethane injection is a solution.
Example of ICF Foundation Wall with some of the foam removed exposing the concrete and the flaws.
1.If you find a crack, you can inject either Polyurethane or Epoxy. 2. If a plastic snap tie is leaking, you can use polyurethane. However, if you have one leaking, there are probably several. 3. With these foundations, a void in the concrete is common, and the best solution is to fill it with epoxy grout. This repair method is a structural solution to missing concrete. You can trowel into the void an Epoxy grout Grout is a thick epoxy with sand added to form a very thick paste and is worked into the void area. We have a separate information page with a complete article regarding ICF Foundations here. 4. Be aware with ICF foundations, if water penetrates in many locations, excavating and installing an exterior membrane may be the only repair option.
How do I repair a Cinder Concrete Block Foundation?
A Cinder Block Concrete Foundation is usually built on a footing or slab, depending on the building’s weight. Cinder block walls are stacked and mortared to form the desired shape before the subfloor or structure is constructed. These foundations are fast to build but usually have a hollow space within the block that can let water build up inside the block and are susceptible to being pushed in or damaged by soil that freezes. They typically crack at the mortar joints.
How do I repair a Cinder Block Wall?
Cinder block foundations are not difficult to repair, but the correct diagnosis is essential. If the joints between the blocks have minimal cracks, the mortar can be re-applied. Most home improvement stores have premixed mortar cement. All you need to do is add water and replace the cracked mortar.
How do I repair Bowed Block Wall?
The most common cause is external soil pressure and expansive soil pushing against the foundation, resulting in breaking or bowing. Carbon fiber straps or unidirectional carbon fiber that is epoxied every four feet at a minimum from the wall's base to the top can be applied to stabilize this problem. The carbon fiber’s holding strength can be multiplied if the bottom and top anchors are installed. The process is straightforward. It requires :
The cinder concrete block needs any paint or parging coat removed with a diamond cup wheel on a hand grinder. A 6-inch wide area needs to be prepared from top to bottom on the wall every 4 ft along a complete wall. Epoxy is applied to the wall and then attach the backside of the carbon fiber to the wall. If used, install the top and bottom anchors. Apply more epoxy over the strap. Repair a complete side of a foundation as an entire structural unit. Repairing only one part of a wall is not recommended.
Wall Bowing is when the wall has cracked in a block wall at the mortar joints and moved inward. They can be stabilized with carbon fiber strapping. If severe enough, excavation may be required and the wall pushed back in place, but this is something that you should consult an engineer and a general contractor who has done this before.
Bottom wall shear
is when a course of blocks near the bottom of the wall has shifted inward. You can stabilize small shifts with shear pins installed between the footing and bottom course blocks. You should consult a building engineer to inspect if it is excessive. Some carbon fiber wall kits include a stainless steel or carbon fiber staple for a bottom anchor acting as shear pins.
Top of Wall Tipping
When the sill plate on top of the last block course or the top course of blocks slips inward, causing the wall to lean in, usually caused by the main subfloor detaching from the top of the foundation wall. This problem can be best stabilized and stopped by adding bracing to the floor joists connecting the wall, or another option is top of wall Necktie Anchors. They attach the building rim joist to the wall halting all movement, and you can use it in conjunction with carbon fiber wall applications.
If you have water leaking out of the bottom
of the wall, you need to determine if the water is getting in at the exterior ground level and leaking into any broken blocks or joints. Unfortunately, if the water is getting inside the block from the exterior, you may need to excavate and install a waterproofing membrane and weeping tile system. Once the water gets inside the cinder block, the industry has solutions to drain off this water at the bottom of the wall without excavating, but this does not fix the underlying problem. In these cases, we recommend you call your local foundation experts to assess as there can be many reasons for this water being present.
How do you Repair Pony and Footing Walls?
They are short concrete walls either built from poured concrete or cinder block that form a crawl space for a building. This type of foundation may not suffer from leaks, but cracks may develop from structural stress.
Footing walls can be poured concrete or cinder block but poured concrete is the most common. The most common height is four feet tall or less and is repaired in the same way as regular foundations as detailed previously. We have found that many older buildings with these short pony and footing walls suffer from a lack of reinforcement when originally built. A structural repair would include epoxy and a combination of carbon fiber straps or stitches. This repair method is not the only method and may vary in your local area.
They are short concrete walls either built from poured concrete or cinder block that form a crawl space for a building. This type of foundation may not suffer from leaks, but cracks may develop from structural stress. How do I repair Foundation Footing Walls? Footing walls can be poured concrete or cinder block but poured concrete is the most common. The most common height is four feet tall or less and is repaired in the same way as regular foundations as detailed previously. We have found that many older buildings with these short pony and footing walls suffer from a lack of reinforcement when originally built. A structural repair would include epoxy and a combination of carbon fiber straps or stitches. This repair method is not the only method and may vary in your local area.
Some short walls in areas that freeze, the footing wall may be as deep as four feet below the surface, to be below the frost line.
Step1 Example of a broken footing for a Garage near the front corner shows after it has been prepared to install carbon fiber staples to help add strength to the epoxy injection. Carbon Fiber stitches, staples, or strapping can be used depending on the strength required.
These cracks are structural, require at a minimum an epoxy injection.
Step 2 Epoxy injection and the installation of carbon fiber staples have been completed. Tip: applying some sand to the uncured epoxy paste will allow for cement parging to bond correctly.
Step 3 A pre-packaged mortar cement mix was used, so only water needed to be added, then applied to match the current parging style.
Step 4 Example of garage footing repair after the parging cement has cured.
How to repair around Pipe Penetrations.
These leaks usually happen when a pipe or some other pipe penetration installed in the foundation wall is left unsealed, allowing water to enter the basement past the pipe. Some common problems include items such as wood that were left by mistake in the forms when the concrete was poured and after many years have rotted out. Services installed through the foundation wall without sealing, such as drainpipes, electrical lines, or conduit pipes.
You can resolve pipe penetrations with a standard polyurethane or various versions of these resins injected around the pipes in a poured foundation wall.
If a piece of wood or original concrete form inside the wall is now leaking, drill out the material, and fill it with epoxy grout or structural foam. Structural foam is a unique polyurethane resin that foams up and exerts pressure as it cures very hard.
Block walls with pipe penetration that leaks, unfortunately, require that the exterior be excavated to the pipe location and sealed from the exterior because the concrete blocks are hollow. You must prevent water from entering the hollow blocks and draining to the interior of the wall. Snaptie or wire tie leaks. Snap ties are a metal connectors installed inside the concrete forms to hold them in place during the concrete pouring.
After the concrete has cured, the section of snap tie exposed on the exterior should be snapped off and sealed to prevent rust, which will eventually allow water to penetrate through the wall. If water does penetrate the snap-tie hole, the best solution is to inject an Ultra-Low Viscosity Epoxy. This method of repair will stop the rusting and bond the concrete and metal together. If you inject it with polyurethane, it will not prevent the snap tie from rusting in the future, so epoxy is the only long-lasting choice.
The joint in a basement between the floor and a poured concrete wall or a block wall may have a gap or appear to be a floor crack. Concrete basement floors are poured in place, usually after the foundation walls have been completed.
This concrete floor may shrink during the curing process, leaving a gap between the wall and the floor. This is normal, and some slabs shrink more than others. Sealing with compounds to prevent Radon Gas from escaping out of this joint might be required depending on the local building code.
Placing anything with no flexibility and creating a solid connection at this joint may create a new problem. The floor slab is usually floating, meaning that the slab may move up and down slightly due to the soil moisture conditions below. This is normal. Bonding to the foundation walls may cause the floor to crack or buckle at the floor wall joint. Should water be coming up from the floor at this joint, it is a symptom of a failed weeping tile, soil drainage, or sump pump system, and sealing the joint may cause a hydraulic lifting action of the floor from water or soil pressure below. Soils tend to swell when saturated with water.
Things that can be done if you have water coming out of the floor: 1. Make sure your sump pump, if you have one, is working correctly and pumping below your weeping tile level 2. Some old homes before 1987 had their weeping tile draining into the sewer drains. Most had a backflow preventer installed, and it may be stuck shut requiring an inspection. 3. Your weeping tile may be silted up, preventing it from draining correctly. This would force water under the footing and then enter the basement. It may require a plumber to snake the weeping tile if possible.
How to Repair Garage Floor Cracks
1. V groove out any cracks using a hand grinder with a diamond cutting blade and vacuum to clean and remove debris. 2. Fill with a product like Roadware 10 Minute Concrete Mender, E555, or similar polyurea or urethanes. Most products will mix great with silica sand for fill volume and cure in under 1 hour. Epoxy is ok but is usually thicker and has a much longer cure time. 3. You can cut the product with a razor scraper when it is gelled, or use a hand grinder with a diamond cup wheel to grind flat once it is cured. Use a dust shroud and a vacuum. 5. If the concrete is weak and reinforcement is needed, you can also install carbon fiber stitches every 12 to 16 inches apart. 6. Garage Floor repair is the same process, but most floors are generally better quality concrete. See our 10 Minute Concrete Mender
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