What

Basement waterproofing is a treatment for cellars and basements to make them dry and usable.

The waterproofing method can also apply to ground-floor rooms particularly in older properties where the floor is below external ground level. It also applies to service pits in garages and workshops, and to basement conversions.

Where

The problems occur when water is drawn from the ground into your cellar or basement. Water can seep in laterally due to hydrostatic pressure against the building if the water table is high. Dampness can also enter your building by ‘capillary action’ where it is drawn from moisture in the ground.

There’s a good technical description in Wikipedia of Water table – it’s the level of water stored in the ground. This goes up and own and it rises when it rains a lot. The pressure of water in the ground causes dampness to flow into your basement, cellar or service pit.

It may be worse if your property is on a flood plain. But it doesn’t necessarily only happen on flat ground. For instance there was a problem with a house on a hill, where the water table rose after a heavy storm, and dampness came into the ground floor.

How

Before any internal works it is important to check that outside your property the water runs away, and your surface and land drains are working well. Your downspouts and guttering should be in good order, feeding into the drains. Also, make sure that there are no crack and holes in the foundations, basement walls and floor.

To damp-proof a basement or cellar, there are two approaches:

A cement-based waterproof render applied to the walls and floor. This will hold the water back.

A cavity drainage damp proof membrane that channels the moisture into a drainage system around the base of the walls and under the floor. The water is moved away to the outside of the building, usually with a sump and pump. Your system could have an extra level of protection such as a sump pump alarm or battery back-up pump.

Click the link for more about the technical solutions for basement damp-proofing.

Who

Professional help is essential to achieve a high-quality, durable and effective solution. There’s a good article about what to look for in a basement damp-proofing contractor here. The questions you need to ask about your contractor are: