Fix common house foundation problems

The foundation of your house shouldn't require much work at all, if any. But when it does, it's likely to be one of three culprits that needs fixing.

• Condensation in the basement won't seriously harm your foundation, so you could do nothing. If you want to prevent it, first make sure that all of the bathroom, kitchen and dryer vents in your home are venting to the outside.
• If any of these air-exhaust vents runs through the basement, make sure all the pipe joints are airtight.
• It may also help to insulate cold-water pipes in the basement. Otherwise a dehumidifier will solve the problem.

Water pressing against your foundation is not a good thing — in extreme cases, it can collapse a wall — though water will usually start pouring through a crack first.

Hydrostatic pressure is so tremendous that coating and patches applied from the inside usually fail eventually, so it's best to prevent hydrostatic pressure in the first place. Here's what to check in order from simplest to most difficult to correct:

• Check to make sure that leaky gutters or downspouts are not dumping water directly onto the foundation.

• Use splash blocks under your downspouts or roll-up hoses attached to them, if necessary, to direct water farther away from the foundation.

• Don't pile shovelled snow against the foundation.

• If your basement has window wells, keep them free of snow in winter. If you get a lot of snow, consider installing window-well covers — clear plastic bubbles that let light in but keep snow, rain and debris out. Make sure that the wells have at least a few centimetres (inches) of gravel in the bottom for drainage, and keep their bottoms free of leaves and other debris.

• Keep water flowing away from the house. You may have to redo the landscape so the ground slopes away from the house; a minimum slope of 15 centimetres over three metres (six inches over 10 feet) is advised.

• In extreme cases, you may need to have a trench dug around the foundation to install gravel and drainpipes. If this is done, the outside of the foundation wall should be coated with a waterproofing compound.

If water is leaking through a crack in the foundation, but not seeping through the whole wall, you can usually solve the problem with hydraulic cement.

This material, available at any hardware store or home centre, hardens fast (even underwater), expands as it cures and will plug even a gushing leak in minutes. Of course you are better off using it to plug cracks and holes before water starts pouring in. Here's how:

1. Chip off any loose material around the hole with a cold chisel and a ball peen hammer. Make the opening larger inside than at the surface to lock the cement in place. Wear safety goggles. Brush away debris.

2. Mix a heaping handful of hydraulic cement with water. When it becomes stiff enough to form into a ball — after a minute or two — it's ready to use.

3. Wearing rubber gloves, push the cement into the hole and hold it there for a few minutes until it hardens.