Q Hi, Bryan. Hoping you can make a suggestion about our 35-year-old house’s basement floor. Recently, we’ve noticed cracks appearing in the concrete and some small patches where the concrete seems to be disintegrating. What causes this and what can we do about it? Some people say nothing and others say the whole floor would have to be replaced. We don’t know who to trust!
A Hi, Cathy. You’d be hard-pressed to find a basement slab, foundation or any other concrete structure without a few cracks. Large slabs, sidewalks, and floors will often have expansion joints or saw cuts in them — not to stop the concrete from cracking, but to help it decide where to crack. If the cracks aren’t expanding, or you don’t have moisture coming up through the slab, they’re generally nothing to worry about. In some cases, the material under the slab may compact a little, or be undermined by groundwater — so you’ll want to be sure that your slab doesn’t have large hollow pockets under it. To put your mind at ease, you may want to bring in a home inspector to have a look. Generally, however, small cracks that aren’t actively expanding aren’t an indication of a serious structural issue. Hope that helps.
Q Hi, Bryan. We recently looked at a house (for sale) with the garage concrete pad full of gaping, criss-crossing, jagged cracks. The owners had moved everything out of the basement to the garage and would not move things in the garage for a better look. Also, the basement was newly finished and one wall had a double wall. So there was the concrete foundation exterior wall, and then another wall inside — with a space of over a foot between the two walls. The interior wall was the studs and framing and drywall. Why would this be done?
Cindy and Bob S., Toronto
A Hi, Cindy and Bob. When it comes to the large cracks in the garage slab, I’ve seen it before. When concrete pads are poured, they have to be on either undisturbed soil or very well compacted backfill. When foundations are dug, there is often a lot of backfill that needs to be put back into the garage area around the foundation. If this backfill wasn’t compacted properly, it will eventually settle, sag and crack. There is a way to jack the slab back up into place if the damage is not too severe, called slab (or mud) jacking. A hole is drilled, and either a cement or foam mixture is pumped under the slab to raise it back into its original position. If the slab is too damaged, it may have to be replaced or a new slab poured over top of the original. Your best bet is to get a qualified concrete contractor in to take a look.
Down in the basement, perhaps the foundation wall isn’t straight and the wall was framed along the path of least resistance or there are obstacles such as corners or pilasters. Or it’s possible that your basement was finished by someone who didn’t have the knowledge or experience to finish it properly and maximize the space. We generally see anywhere from one to three inches of space behind the exterior framed walls depending on how straight and plumb the foundation walls are, but 12 inches and a double wall sounds excessive. It certainly warrants further investigation.
Bryan Baeumler, is a Gemini Winner and host of HGTV’s Bryan Inc., Leave it to Bryan, Disaster DIY, Canada’s Handyman Challenge, and House of Bryan. Based out of Ontario, Bryan owns and operates Baeumler Quality Construction, a full service construction and renovation firm. His network of contractors and home service providers Baeumler Approved, helps homeowners connect with quality companies across Canada. For more information visit bryanbaeumler.com.