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01509 216 323

How to Tank Walls

Tanking Membrane and Tanking Slurry

 

Why you need Tanking

Damp rooms often need tanking, particularly if they are below ground level. If your walls are damp, it doesn’t only cause decorative issues but can also lead to a cold home. Tanking a room can help tackle mould and damp problems, as well as stopping water penetrating your building.

When you need Tanking

If your inner walls are colder than your outer walls, condensation can form on them, and with condensation comes mould, unless you have adequate ventilation. Rising damp can also introduce salts into your wall, and because these are hygroscopic (water-attracting) it will only make problems worse. Not only do salts attract damp, drawing it from the air, but they can also leave an unsightly finish and damage the plaster.

Many people want a quick fix. However, if you’re tanking, it’s important to remove any plaster that’s been contaminated with salt as otherwise, you’re only covering the problem, not treating it.

Tanking isn’t just used in cases of rising damp. If you’re converting a basement or have an area of your home that’s below the level of your damp proof course, the walls will automatically be damp as the substrate contains moisture.

 

What is Tanking?

There are two main methods for tanking: Tanking Membrane that comes in sheet form and Tanking Slurry that is chemically designed to bond with damp masonry and form a waterproof layer. The right method will depend on your exact requirements and the type of damp you are dealing with. You may also need to use a combination of these methods to ensure your walls stay dry. In the article below we aim to help you choose which is the right type of tanking for your project.

 

Type 1: Tanking Membranes

Tanking Membrane consists of a studded plastic sheet that is fixed to the wall with plugs and sealed with tape. These sheets are quite easy to apply and the studs allow for ventilation between the wall and the membrane.

The studs on the sheet face into the damp wall which allows air to circulate and moisture to run down to a drainage point. Battening can be attached onto the sheets to allow insulation boards to be attached or suitable plasterboards, which can then be decorated to suit the room.

Tanking Membrane comes in all types depending on use, but it can also come as a complete kit including membrane plugs and sealing tape.

Type 2: Tanking Slurry & Wall Coatings

There are two types of coating: Liquid Bitumen and Tanking Slurry.

Liquid Bitumen certainly has its uses, it can be hard to apply to masonry in heritage buildings (assuming you’d even want to!) or damaged substrates. If it’s applied incorrectly and doesn’t cure, it can peel away from the wall or render coats. As such, it’s best reserved for external coating below the damp proof course, or small jobs.

Tanking Slurry is easier to apply, though you still need to clean and dampen your substrate before application. It’s designed to be attracted to the water in the masonry and mortar, and is easier to apply than bitumen. Tanking Slurry is great as an exterior coating on foundation walls or partial below-ground situations.

 

 

How to tank a wall

Below we give you two guides. The first explains how to tank a wall with tanking slurry and the second shows you how to tank a wall with tanking membrane.

 

 

How to Apply Tanking Slurry

Step 1: Start by cleaning your walls, removing old plaster, dust, paint or render then wash thoroughly with water. Watch for any leaks, if water is seeping from the walls you’ll need to use a quick setting plug such as Restor Rapid Set to stop the flow until it is properly tanked. Once the wall is clean, apply Salt Neutraliser, to prevent any salts from entering the new tanking slurry you’re going to apply. Use two coats, wetting the surface with clean water between each coat.

Step 2: Once you’ve treated the wall with RUK Salt Neutraliser, fill any holes you can see with mortar (sand and cement) (NB: if you have walls made of soft stone, you may want to avoid using cement: call us for advice on alternatives).  Do not use a waterproofer instead SBR Bonding agent is good and prevents damp getting through.

Step 3: Apply a coat of tanking slurry. Make sure you use the right amount of water as mistakes can make it ineffective. Once mixed, apply it to the wall in horizontal strokes, using a masonry brush.

Step 4: After you’ve applied the first coat, let it set for approximately 6 hours then apply a second coat using vertical strokes. This should help ensure you cover the wall without leaving any patches uncovered. Now, leave the second coat to cure and, once it’s totally dried out, re-plaster using renovating plaster or render with sand and cement, or paint over with microporous paint. Again SBR Bonding Agent can be used between all coats.

How to use Damp Proof Membranes

Damp proof membranes aren’t technically tanking, but are an efficient and simple way to damp proof below ground. They consist of a studded plastic sheet that is fixed to the wall with plugs and sealed with tape.

The studs allow air to circulate behind the membrane, and excessive moisture can be drained into a sump pump using drainage channels. The size of studs varies: as a general guide, the damper the wall, the bigger the studs, though our experts can help guide you through the different membrane types to let you know which one is right for you.

Once the membrane is applied, it can either be plastered directly onto, or battened to allow plaster boarding.  You can also use membranes on damp floors.

Whichever form of tanking you use, it can help you fight water ingress, ensuring your home stays free from damp. Obviously, it’s also important to ensure you have adequate ventilation to avoid condensation related damp – but that’s another matter entirely:  https://www.restorationuk.com/about-restorationuk/restorationuk-news/condensation-analysed 

Check out our Membrane Fitting Guide.

 

 

Further guidance with wall tanking

For further help on tanking a wall and selecting the right products for the job, give our technical sales team a call on: 01509 216 323.

 

 

You may also be interested to read:

Slimline Plaster Membrane Fitting

Moisture Readers

Waterproofing Basements

 

Call us on: 01509 217750 for further information on tanking products

 

Need some advice? Call 01509 216 323

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Restoration UK Ltd
Unit 3, 18 Hanford Way
Loughborough, Leicestershire
LE11 1LS

01509 216323
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