How to waterproof a garage

If you want to use your garage as living space, or protect stored items from getting damp, waterproofing your garage makes good sense. But, how do you go about it?

Image Credit

Use tanking slurry

One of the easiest and most cost-effective ways to waterproof a garage is to use tanking slurry. According to DIY Doctor tanking is the formation of a waterproof barrier from a liquid coating which sticks to masonry that is damp.

Tanking slurry is a mixture applied on walls to waterproof them. It can be bought ready-to-use, or you may need to mix it with water beforehand.

Image Credit

Preparation is key

You first need to properly prepare the surface of the garage walls, which means they must be clean and free from any plaster, paint, render or coating. You need to apply the tanking slurry to the original brickwork.

Before you begin, now is also a good time to repair any cracks or holes that may be present in your walls. While you’re at it, why not see if any other jobs need fixing in your garage, to prevent damp and moisture from entering in the first instance. If your garage door has seen better days, consider consulting a company specialising in garage door repair Stanmore has some good examples. A Garage Door repair Stanmore company will also help to ensure your garage is secure, as well as free from letting in damp.

Preparing the slurry

If you need to mix the tanking slurry with water, wear a facemask and goggles to protect your skin. Mix for about three minutes and then leave it to rest for a further minute, before giving it a final stir. You should be aiming for a consistency similar to batter. Only mix enough slurry for about 30-45 minutes worth of work.

Before you apply the slurry, your garage walls need to be wet, so apply clean water to the substrate.

Applying tanking slurry

Normally you need to apply two coats of tanking slurry to waterproof your garage. Apply the first coat directly to the brickwork, up to about one metre high. Allow up to 24 hours for this initial coat to dry, before applying the second coat. After a couple of days, the slurry will cure.


Apply a render coat to the walls approximately a day or so after adding the slurry.