Renovation & Design

Foundation leakage a common problem

QUESTION: We have water leakage underneath the wallboard on one wall of our basement when there is severe rainfall. At this point we haven't removed the wallboard in that section to actually view the wall. However, one of the options suggested to us to deal with this type of problem is epoxy injection. What are your thoughts on this process?

Thank you for your help. David Singer

ANSWER: There may be a couple of different approaches to fixing the seepage issue in your foundation but first you must expose the section where you are seeing the damage. This will allow you to have the problem properly evaluated and then decide on how to proceed.

Foundation leakage is one of the most common problems facing homeowners, no matter where you live. It often occurs only during heavy rains, as with your home, or during the spring thaw, but it can also be a nagging, chronic problem. The issue can be due to simple deterioration of the damp-proofing on the outside of the foundation and/or blockage of weeping tiles, but can also be due to cracks in the concrete.

If you have a very old home with a stone foundation, the leaking can be due to typical deterioration in the mortar that binds the stones together. If that is the case, epoxy injection is not an option, so I will assume that you have a concrete foundation for the purpose of our discussions.

Whatever the actual cause of the water intrusion, it will be very tough to determine without seeing the foundation wall. From the outside, the foundation wall may be partially visible, but only for a short distance above grade. The only way to get a good idea of the condition of the foundation wall is to remove the wall coverings and insulation. If you've had several seepage incidents, the wall covering may be damaged and need replacement anyway. Removal of moisture-damaged sections -- especially if it's drywall -- is important to prevent mould growth.

So, the first step is to remove a full sheet of drywall in the vicinity of the leakage and see what the wall looks like behind. Once you remove the wall covering and insulation the initial item to inspect is the condition of the wood framing supporting the wall sheathing.

If the bottom plate is black and soft when probed, it's rotten and will have to be replaced. That is an indication that the moisture intrusion has occurred several times. If the vertical studs are damaged in a similar manner, that's evidence that your problem has been going on for a long period of time.

In either case, the damaged wood should be cut out and discarded. This also will allow better access to the foundation walls. If the wood is only slightly stained and does not allow a screwdriver to easily penetrate the surface it should be sound enough to leave in place.

Once the interior of the foundation is exposed in the area where the water was seen on the basement floor, examine the condition of the interior surface to help you determine the defect that is causing the leakage.

First, you should look for any obvious cracks or holes in the concrete. If you see vertical or slightly diagonal cracks larger than three or four millimetres wide, this is the likely spot that the water is coming through. Also, look for rusty stains running straight down from old form ties holes.

If no cracks or leaking snap ties are visible, or if there are only small hairline fissures, look further at the interior surface of the wall. If the surface is spalling, crumbling, or if paint can be seen flaking off in large chunks this may give you a further clue in identifying the problem.

Finally, if the concrete is in generally good condition but there are large amounts of white salts, or efflorescence, on the surface, that will also help to decide on the type of repair needed.

Epoxy injection is a good method of stopping isolated foundation leakage if the water is coming in through small to moderate-sized cracks or through rusted snap ties. To inject the epoxy, the entire crack will have to be exposed and small holes drilled in various areas of the crack or the rusty snap ties.

Epoxy is a very hard and durable compound that has proven effective in sealing small foundation cracks and actually strengthens the area to prevent enlarging of the opening due to further water damage. While the epoxy method is costly, and fixing more than a single small crack can be quite expensive, it's normally less costly and a lot less work than digging up the soil outside the foundation to expose and repair a crack in that manner.

You will have to replace the interior wall covering after the crack remediation, but it was probably water-damaged anyway.

If you find more extensive deterioration or no visible cracks or holes when you expose the interior of the foundation, then you will have to look at alternative methods for stopping the water. Whether it's deteriorated damp-proofing, plugged weeping tiles or surface deterioration to the outside of the foundation, it will have to be repaired from the exterior. This will involve digging a trench outside the entire area effected, cleaning the foundation walls, replacing the damp-proofing or installing a membrane, replacing weeping tiles and then backfilling and landscaping.

While this sounds somewhat unachievable, it's commonly done and may be about the same cost asfilling several cracks with epoxy. Exterior repairs will also have the added benefit of replacing the weeping tile, which is an important water-management system.

If you're fortunate, when you remove the wall coverings you will find a lone, obvious crack responsible for the leakage which will allow you to call a foundation contractor to inject it with epoxy and fix the problem at a moderate cost.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home & Property Inspectors - Manitoba ( Questions can be e-mailed to the address below. Ari can be reached at (204) 291-5358 or check out his website at


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