Can you damp proof breeze blocks?

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Breeze blocks are a common building material used in the construction industry. In new construction they are often used for the internal leaf of a cavity wall. The outer leaf will then be constructed of more aesthetic masonry. This will usually be facing bricks of some kind or stone.

Also, blocks are considerably cheaper and considering they will be covered internally it makes sense to use them here to reduce construction costs.

In some instances, you will find properties where both the inner and outer wall are blocks. In this case the external wall will usually be rendered.

There are several ways you can damp proof breeze blocks, and this can be done both internally and externally. Some common options include:

  • External render
  • External masonry paints
  • Internal tanking (membranes or slurry’s)
  • Also, condensation can be reduced by improving insulation

The option you choose will depend on the circumstances. For example, a single skin garage may need a different solution to a habitable space.

Are breeze blocks waterproof?

can you damp proof breeze bloks

Breeze blocks are not completely waterproof and are generally more porous than bricks and stone. This means that water can permeate through more easily. This is not a problem when block is used internally as they are not subject to weather like the external masonry.

Internally, they will also be covered with plasterboard and decorated. Unless there is an issue with penetrating damp, or an internal leak they are unlikely to meet a water source. Hence, they don’t really need to be waterproof in this scenario.

When blocks are used externally, they are usually rendered. A common example of this would be a garage or a shed. If the blockwork is exposed to driving rain it is very likely that damp will find its way through to the internal surface.

Ways to damp proof breeze blocks internally

In some cases, damp proofing internally will be your best option. There are several reasons for this, including, poor access to the external surface, or wanting to add an extra layer of protection internally.

One of the most popular ways to waterproof breeze blocks internally is using a tanking system. This can be a membrane or a slurry.

In most cases a slurry will be the best option, as it can be applied very easily. It comes in a powdered form and simply needs mixing with water. Once you have mixed the slurry, it can be placed in a bucket and applied to the surface with a stiff masonry brush.

To add an extra layer of damp-proof protection you can apply batons to the wall and fix foil backed plasterboard as your finished surface.

 Also, if you think condensation might be an issue to the surface being cold. You could opt for an insulated plasterboard instead. This combination would damp proof and insulate your internal breeze blocks.

Ways to damp proof breeze blocks externally

If breeze blocks are used in the external surface of a building, it is advised that you damp proof from the outside. A good example of a building that may have external blockwork, is a single skin shed or garage.

These types of non-habitable building are quite prone to damp for several reasons. Firstly, they are usually cold and due to blockwork being more absorbent can suffer with damp. This is especially true if they are not protected externally.

The best way to damp proof from the outside is with a render. This will need a scratch coat and then a final coat on top.

The mix you use for the render can vary depending on who you ask. Many plasterers will use 4 parts rendering sand to 1 part cement for the scratch coat and 5:1 for the final coat.

Renderers will generally use a plasticiser to reduce how water permeable the render is. Alternatively, you can add 1 part lime to the original sand cement mix. Lime is a waterproofing material that was used a lot in older period properties (before cement). It offers waterproofing qualities, as well as excellent breathability.

You can see a good video of how a sand cement and lime mix can be created and applied in the video below.

Need help damp proofing your blockwork?

For large, more skilled jobs, such as rendering you should probably hire a professional. If render is applied poorly, it can lead to future problems with damp. The result is you will end up doing the job twice and you could suffer more damage from penetrating damp.

There is a cost to hiring in skilled trades. However, you can save a significant amount by getting quotes online. By far the best way to do this is comparing quotes. Doing this means you can read reviews on a company’s profile, and you will likely get quotes from many different companies.

All these companies want the work, and they know that their competitors are bidding on the job too.

To see how much you can save by comparing local rendering companies Click Here

If you need help with any other type of damp proofing you can also compare damp companies and get free home surveys by Clicking here


There are several ways you can damp proof breeze blocks. Some of these can be simple DIY projects that you can do yourself, such as applying a tanking slurry, and some will require the help of a professional.

One thing you should always consider, is an expert will be able to do most jobs to a higher standard. Not only that, they will usually guarantee their work for many years (even decades).