Q We have a crack in the foundation wall of our log cabin. Do we need to be concerned about it structurally? And could termites enter through it?
A Put it this way: a crack doesn’t have to create structural troubles for it to be a problem. Cracks are ugly, suspicious things that aren’t easy to fix, and even one that’s no more than a hairline could grow and create all kinds of difficulties.
I would say any crack wider than 2 mm is a problem, especially if it admits water or increases in width or length, or if its faces grind against each other with changes in temperature and humidity. All of these indicate foundation movement, and that’s not good.
As for termites, those pests can slip through a crack that’s half a millimetre wide. If you live in an area where termites are common, have your home inspected by a licensed pest-control contractor.
The good news is that in most cases only large cracks indicate structural trouble. You’ll need to contact a structural engineer or foundation repair company in certain cases, such as if the crack wraps around a corner or if there’s a horizontal crack with a sagging wall underneath. Both of these indicate that the soil supporting the foundation is moving (horizontally or vertically) and taking the foundation with it.
It’s tough to fix a crack. It’s one thing to simply fill it with epoxy and hope that it holds. It’s a much larger matter to evaluate the foundation inside and out and determine what’s causing the crack, undertake those repairs, and then seal the crack shut for good. That kind of repair is expensive and often involves reducing the hydraulic forces acting on the foundation by installing drainage pipes, gravel, filter fabric, a sump pit and a pump. In the worst cases, the foundation may need additional support from piers driven next to it. It takes an experienced foundation repair company to do that work.
If you’re going to attempt a DIY repair, do your homework. A number of sites offer smallscale versions of epoxy injection kits used by contractors, and you can still buy tried-and-true cement-based products to carry out repairs.