How to use waterproof tanking slurries

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Leaking Basement Waterproofing

How To Use Waterproof Tanking Slurries

This is a simple and easy way to waterproof basement spaces, but be careful of the surface preparation.

Tanking slurries are a useful way of waterproofing below ground spaces. They work by creating a physical moisture and vapour barrier that prevents water from coming in through the walls and the slab.

Although they are easy to apply, there are a few very important steps that you will need to follow to ensure that they work.

Waterproofing of a basement or converting a cellar:

Koster NB1 is a really effective waterproofing system designed for the negative side of basement walls and slabs. It can resist up to 13bar of water pressure, which is a lot!

Like with all tanking slurries a really good bond to the walls and slab are required. This means that your will need to follow these important steps:

1- Surface preparation.

Paint, salts or other surface contaminants must be removed from the walls and the floor before the tanking slurry is applied. In some cases this may include grit blasting or grinding the surface using a bush hammer.

2- Strength of the substrate.

There’s no point in applying your high performance tanking system to loose or damaged backgrounds. This means that the floor slab may need to be inspected and repaired. Areas of loose mortar in masonry may need to be repointed.

3 – Pre treatment. 

Some building materials, such as new concrete, can generate free lime which could damage the tanking layer. This free lime should be encapsulated using a free lime blocker such as Koster Polysil TG500

4- Internal Angles.

Right angles in the structure can create problems for waterproofing systems.

Koster Repair Mortar Plus can be used to form nice, rounded fillets at internal angles.

These fillets can spread the loading of any water ingress and remove any pinch points.

5- Applying the waterproofing.

The Koster NB1 tanking slurry should be applied in two coats in accordance with the product data sheet (you can download the data sheet from the Koster NB1 product page, here). When applying with a brush the first coat should be applied with vertical brush strokes, the second with horizontal. This ensures even coverage.

6- Don’t Panic – It will “Sweat”!

As the special formula of Koster NB1 cures, it will “sweat”  and beads of moisture will be visible on the plaster surface this is perfectly normal.

7- Render Coat.

Although you can leave the NB1 exposed, it doesn’t really look that nice, its great at holding water back but it’s not that easy on the eye.

Koster Restoration Plaster is the ideal system to provide a long lasting finish over the Koster NB1 tanking. It’s available in white too, which you can buy here.

Need help in selecting or installing the right waterproofing system?

Let us know our team of waterproofing experts will be happy to help.