Mike Holmes: Five tips for patching basements
**Mike Holmes Oct 21, 2011 – 5:30 PM ET | Last Updated: Oct 21, 2011 5:13 PM ET **
Let’s say you’ve discovered a leaking spot in your basement. Just one. That’s how it usually starts. Homeowners have just one problem area, or they are only aware of one leak. So what should you do about it?
The dilemma most homeowners face is that one small leak doesn’t quite justify the expense of an exterior waterproofing renovation. (Because, believe me, it is a big, expensive job.) The question I get over and over: Is a spot repair enough?
Just to be clear, a spot repair is when the foundation is excavated and exposed directly on the opposite side of the foundation wall where the leak is. And it can be a gamble that doesn’t pay off. You might go through the effort and expense of trying to patch a spot, only to find that, at best, you’ve put a Band-aid on the problem, or, at worst, you’ve completely missed it.
I think most homeowners understand that specifically fixing one basement leak is a lot like fixing just one leak on a roof. Odds are, where there’s one leak, there are more looming just around the corner.
The structure has allowed water through in one spot, and since wear and tear of building materials progress at different places, I will bet that another leak in another location will appear before you know it. That’s why it’s better to replace all your roofing shingles at once than to do a patch, and that’s why spot repairs on your foundation can be a gamble for long-term dryness.
But let’s look at patching a little more closely. There may be some merit to fixing just the one area. The foundation leak may be caused by an obvious problem that becomes clear as soon as the outside wall has had the dirt removed from it.
Exposing the exterior side of your foundation is extremely important. You need see the problem from the wet side of your home, to know for sure exactly what is causing the leak on the inside. And it could be several factors all combined that are creating too much water pressure against the foundation.
To do a spot repair, you’ll need to have a trench dug eight to 10 feet across and right down to the footings. Once that’s done, there are several things your contractor needs to investigate that might be causing the leak.
1. Is there an obvious defect on the foundation? A crack or hole? Are there tree roots or large rocks pressing up against the foundation?
If so, your gamble has probably paid off. Just remove the cause of the problem and repair the defect and then recoat with a foundation coating and replace the Dimpled Membrane. If tree roots are the culprit, then look around your yard. Are there other trees that are closer to other points along your foundation? More excavating might be required so you can correct that situation before it becomes a problem.
2. What is the condition of the weeping tile at the bottom of your trench? Are they crushed, or clogged with earth and tree roots? Or is there any weeping tile at all?
In this case, you have the opportunity to assess the overall condition of your tile. If it appears to be generally in good shape and just one area is broken by the leak, then congratulations! Your spot repair was a good choice. Just fix it and you’re good to go. But if the weeping tile is toast, then you need to consider doing a more extensive repair and replacing the entire weeping system, or adding an extra weeping line that terminates at a French drain.
3. Is there enough gravel around the weeping tile? Or is the gravel choked with earth and all the voids between the gravel are filled in? You can never have enough 3/4-inch clear gravel around your weepers, and that needs to be wrapped in landscape fabric to prevent dirt penetrating the gravel.
4. What are the soil conditions around the home? Is it made up of topsoil with a sand base? Or is it mostly made up of clay? This important point is constantly overlooked. If the soil is black earth and sand, then good overall drainage is likely present. However, if there is mainly clay, then the water against the foundation is being pressed into the wall under extreme pressure by a substance that doesn’t readily absorb water.
In this case, a spot repair isn’t going to work too well, because the groundwater will find the next weakest point in your foundation to push through. But if you only do the spot repair, and add an overly generous amount of gravel to that area, the groundwater pressure should be eased off somewhat in and around that area, as the water fills the air pockets in the gravel. When your whole foundation is surrounded with clay, anything to help the situation is better than doing nothing.
5. What is the age and condition of the existing waterproofing treatment on the house? If the house is a century old, there may be nothing at all. If the house is 50 years old, there may be a parge coating with terracotta weeping tile, and there’s a good chance it has stopped working effectively. That should be replaced with what is now standard building code: plastic flexible weeping tile with a fabric sock and surrounded by gravel with a coating on the wall and footings all protected by a dimpled membrane.
So spot repairs are not completely a gamble. In some situations, they can help, but there is no substitution for the peace of mind a complete exterior repair will provide. Your contractor needs to assess all the factors and discuss with you if it’s worth the gamble of a spot repair, or if a more thorough foundation excavation and repair is needed.