Brick foundation questions
I just want to say I’ve been reading through a number of different articles on this site and it’s an incredible amount of information. Many thanks to Martin and other contributors for offering these resources.
I’d appreciate any advice anyone has to offer as I’ve been trying to research brick foundations as we recently discovered we had a clay brick foundation. I’ve read the common approaches for upgrading but there’s a lot of information and my head is spinning a little bit. We recently had a waterproofing company in to take a look, and the suggestion was exterior waterproofing which is obviously quite costly for a space we don’t really use for anything other than storage and possibly as a gym/overflow area when we have people over (underpinning was also suggested as well). We’re open to it we’d just like to see if there are other options and if we can delay in anyway for financial reasons.
Coming back to this site to research there’s some additional information great information on the old brick buildings and insulation, however, until we solve the water problem I’d rather not insulate. Also, I note that with old brick foundations doing things like insulating walls and/or rim joists is not entirely straightforward either. We are okay leaving the space unfinished for the mid-term future. My questions are:
– can I remove the parging and treat the brick with a liquid and/or vapour sealer? I’ve noticed there are products such as LastiSeal (from RadonSeal) that suggest they can be used.
– is putting another coating of parging (or fixing the current parging) recommended or can the brick be left if a liquid sealer is applied?
– are there any other interior steps we can take that people would recommend?
Some information on the house: 1920s in Toronto brick foundation covered in parging, which is damaged in some areas (“bubbling” and flaking). The parging also seems to vary in thickness around the foundation, in some case you can see a faint outline of the brick in others it’s a half an inch thick. The basement is currently unfinished although there are some supply ducts in the ceiling that heat the space to some degree. There is some water in the spring time each year, usually only once or twice, but nothing after after heavy rain so far, seems to be from one specific spot where the floor meets the wall. Also, we are midway on a downslope in the general neighbourhood but the house does have significant slope away from the foundation to the street (corner lot) although moreso toward the front of the house than the back.
I appreciate any help/advice. I’m also happy to provide more information if necessary.
Thanks,
Craig
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Replies
Craig,
You are correct that it is unwise to insulate your foundation walls if you have a water entry problem.
From a technical standpoint, it is accurate to say that the best solutions involve exterior work, which require excavation down to the footing. This will be expensive.
You have two major problems: (a) water entry (which can be solved by installing an exterior footing drain and by installing a waterproofing system on the exterior side of your foundation), and (b) capillary rise, which is best solved by jacking up your house about 1/4 inch so that workers can slide a capillary break (metal flashing or strips of EPDM rubber) between the top of your foundation wall and the wooden mudsill.
It's also possible to ignore the problems and to leave the basement unfinished. If you go this route, the cost will be much less. If you need more indoor space, it will probably be less expensive to build an above-grade addition than to try to finish your damp basement.
Note that the interior parging on the bricks is intended to be a sacrificial layer. It is an old technique to handle problems with "rising damp" (capillary rise). Don't expect new parging to be permanent; occasional flaking and failure of the parging is normal. The failing parging saves the brickwork from damage.
One solution to your problems is to sell you house and to buy a modern house with a concrete basement with good waterproofing details.
For more information, see Fixing a Wet Basement.
Craig,
Building Science Corporation goes into more detail on why brick walls and foundations are so challenging. (For example, see https://buildingscience.com/documents/insights/bsi-011-capillarity-small-sacrifices).
You might be able to reduce the amount of moisture entering the basement by improving your water management practices. For example, you want to ensure that the grade slopes away from the house on all sides and the gutters are not overflowing and channel water away from the foundation.
Thank you both, Martin and Steve, for your help.
Martin - we have been looking at an addition as an option as well to add space, we were just concerned that delaying fixing the problem would only make it worse. We've also contemplated selling as well...there aren't too many modern houses on the market in Toronto unfortunately. Apparently the previous owners had plans to tear it down and start from scratch, so there's always that option as well. I think at this point patching the damaged parging areas makes the most sense. Would there be any value adding interior water management such as sump pumps or interior French drains at all? I'm not sure if useful but the space is not overly large, roughly 600 sq ft. Anyhow, there's lots of great info, thank you...time to do some more reading.
Steve - thank you for the link. The grade slope outside our house is actually quite good and seems to do a good job of diverting the water (onto the sidewalk a good 8 ft away from one spout which is an issue in winter when it freezes but we just stay vigilant with the shovel). I have thought of re-routing that spout to along the side of the house to another spout in an area with a higher grade. Not sure if that would be a worthwhile measure or not though.
Thanks again, really appreciate the advice.
Craig