Contractor likely best bet for concrete repair

Hey there, time traveller!
This article was published 22/04/2023 (879 days ago), so information in it may no longer be current.

Question: We have a 1986 house with an unfinished basement and exposed foundation with a vertical crack which lets water seep in. What can we do to fix this? Can we fix it ourselves or do we need a professional? If a professional, who do you recommend? I read you article every week, but can’t recall a question such as this. Thanks for your help, Pat.

Answer: Stopping leakage from individual vertical foundation cracks may be possible without disruptive exterior excavation. However, the costs may be similar for professional injection repairs and may not be as reliable.

The typical remediation for foundation cracking is to dig out the soil around the crack, clean the foundation, and cover the area with a liquid foundation damp-proofing or waterproof membrane. Often, a piece of rigid foam insulation, or other sheathing, is applied over the area to protect the repair from future soil damage. The excavation is normally filled with granular material, rather than the existing clay soil, then covered with a layer of topsoil to allow grass or vegetation regrowth. This may be the best way to prevent future leakage as any soil moisture is prevented from entering the breach at the source.

While exterior repairs are preferable, there are often situations where it is not very practical. If there is a large amount of well-established vegetation, such as shrubs, coniferous trees or perennial gardens, then they will have to be removed to dig. Large concrete steps, cantilevered alcoves, garages, sidewalks, driveways, gas meters and fences can all provide a significant impediment to excavating. Some of these can be temporarily removed to facilitate the work, but that will add cost and time. In those situations, interior repairs may be preferable.

The other side to the coin is that interior remediation is likely to have just as many roadblocks as the exterior option. Most foundation walls in our area are covered with wood framing, insulation, and wall sheathing. If the wall covering is taped and painted drywall, or real wood panelling, removal may be very disruptive. There may also be interior partition walls that block access as well as plumbing supply pipes, laundry drains, furnaces, and other mechanical items near the crack. Electrical wiring running through the studs will also have to be avoided when considering fixing the leakage from inside.

For your unfinished basement, with the bare concrete wall fully accessible and visible, repairs from the inside may be the most practical solution. This will normally involve injecting some form of waterproof compound into the entire crack. There may be several types of injections available but the material with the longest track record, as far as I know, is epoxy. Epoxy is an extremely hard adhesive that is created by combining two separate substances and letting them cure. Once it hardens, it should even have more strength than the original concrete. It is resistant to moisture, physical damage and is an outstanding adhesive that will bond extremely well to the old foundation wall.

To answer your second question, it may be possible to do the injection yourself, if you can find the proper product and injection equipment. The epoxy has to be forced into the crack under pressure, which may require some specialized equipment. It may be possible to partially fill the gap with a standard caulking gun, but unlikely that you will succeed in complete coverage, which is very important. You will likely have to inject the epoxy, or at least blow out debris from the crack, using a compressed air system. Prior to this, small holes will have to be drilled at numerous points along the fissure with a hammer drill and masonry bit. The holes will allow the adhesive to penetrate all the way to the exterior side of the foundation wall, critical in ensuring no future leakage. So, if you are an experienced DIYer, prepared to purchase or rent the required equipment, or already have a suitable drill and compressor, then it may be within your reach.

In most cases it will be prudent to call a well-established foundation repair contractor that specializes in injection repairs. Many of the local companies offer this service, but there may be only a handful that have the most experience. Some may try to offer alternative sealants for injection, which may stop the leakage for a certain length of time, but may not be as durable as epoxy. I have seen repairs of this type that have lasted 30 to 40 years without major problems. That may depend on several factors, such as integrity of the surrounding concrete, soil conditions outside the foundation, settlement, and environmental factors. But, the overall factor is often quality of the actual repair. For this reason, I would only hire a contractor that has at least one or two decades of experience with the exact repair and materials used for the crack injection.

The final consideration, as it almost always is with any type of renovation or home maintenance, is the overall cost. As stated above, the overall cost to inject a single vertical crack, which runs from the top to bottom of a standard height foundation wall, may be similar to the fee for exterior repairs. I believe that it is better to do this type of repair from outside, to ensure no water at all leaks into the crack, to prevent future damage from frozen water expansion. Regardless, an interior epoxy injection may be similar in quality and longevity, as long as it is very well done.

Injecting professional quality epoxy into your concrete wall crack may be the most practical solution to stop the water intrusion. You may be able to attempt this yourself, but have a better chance of success hiring a contractor with many years of experience in this type of foundation injection repair.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and a Registered Home Inspector (RHI)(cahpi.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.

trainedeye@iname.com