Cavity Membrane and Damp Proofing

Cavity Membrane and Damp Proofing

How Cavity Membranes Work

If you live in a property that has a basement or cellar and you have experienced damp issues in this space, then it can be quite a frustrating prospect to have so much extra room underneath your property that you are unable to use. Along with this, damp in the basement can also lead to further problems that affect the rest of your home including a nasty musty smell, and maybe even lead to health issues for the people who live in the house. Thankfully, there are various options that you can consider to damp proof your basement, get rid of these problems, and turn it into a space that you can use as an extra room in your home or for plenty of additional storage. For damp proofing a basement that is prone to damp and perhaps even flooding, a cavity membrane damp proofing system is the most recommended option by experts.

What is a Cavity Membrane?

A cavity membrane drainage system is designed for using in a coal vault, basement, or cellar. It is designed to damp proof the area by allowing water in through the internal walls at the back of the membrane. It is a studded membrane that is made using high-density Polyethylene, and it is installed on the walls, floors, and in some cases the ceilings of your cellar or coal vault. It may also have a special drainage channel for the purpose of draining water away from the foundations and towards a sump pump, where it is directed outside and away from the property.

Cavity Membrane and Damp Proofing

Cavity membrane systems are a different type of damp proofing to alternative options such as structural water proofing or tanking. With tanking, for example, a waterproofing slurry is applied to the walls and floor to prevent any moisture from reaching the walls at all. On the other hand, a cavity membrane is installed in a way that there is a cavity left at the back of the membrane, which allows water to get in at the back before it is drained away. If no natural drainage system is available in the area, then a sump and pump can be installed in order to direct the water away from the property and into a suitable area like an external drain. Wall membranes and floor membranes are the two main types of Type C waterproofing membrane to choose from. Floor membranes tend to have larger stud profiles compared to wall membranes. Once installed, the membrane can either be dry lined or plaster can be applied directly onto it.

See also
Rising Damp: A Guide for Landlords

Cavity Membrane and Damp Proofing in London

In London and the rest of the UK, dealing with damp in basements is often a common problem. Many people around the country have had an issue with some kind of damp in their home. If you have a cellar or basement in your London home and want to use it for storage or convert it into a liveable area of the property, then a cavity membrane drainage system is one of the best ways to ensure that it stays dry. Without damp proofing in the cellar, any conversion efforts will quickly become ruined as damp can cause a lot of issues to internal décor including causing plaster to crack and crumble or paint and wallpaper to chip and peel. Along with this it can lead to bad smells and be dangerous to the health of people living in the property, especially if the damp leads to mould in the future.

Why a Basement Waterproofing Membrane is Needed Before Converting the Cellar

If you want to convert your cellar to turn it into a more useable storage area or to create an additional room or rooms in your home, then you will need to have a waterproofing membrane installed. This is because otherwise, you will find it difficult to avoid the several problems that can be related to having damp in the cellar and the internal walls. Without having damp proofing carried out you will not be able to use your basement or cellar for the intended purpose as it will be cold, dingy and any items and furniture in there will quickly become ruined from the damp. You may also struggle to have electricals such as lighting and plug sockets installed in the basement if it has not been damp proofed as this can be a serious hazard. Finally, damp makes the entire house less energy efficient, so even if you don’t want to use your basement as an entire room it is worth getting damp-proofing to improve the energy efficiency of your home and save money on your regular energy bills.

See also
Condensation Control

What is a Drainage Membrane?

A cavity membrane drainage system is a Type C waterproofing that is designed for providing drained protection to a structure. This is a popular option for damp proofing cellars and basements in existing homes. They are also often used for constructing new basements in new build properties. They are necessary as the external earth-retaining walls of the cellar will be subjected to hydrostatic pressure or the build-up of external water pressure on the walls. Although the external basement walls do provide some resistance to this, it can quickly lead to serious damage if there are any weak spots in the walls that allow moisture to get into the basement, which can cause damp issues and in serious cases, flooding. A cavity membrane system will ensure that basements and other below-ground structures such as coal vaults are protected from water ingress problems. The system does this by redirecting and channelling any moisture that gets in through the walls and draining it to a suitable area. It provides a barrier to prevent any water that gets in through the walls from ever reaching structures and items within the basement.

How Do You Install a Cavity Drain Membrane?

When it comes to basement waterproofing, cavity membranes are a popular option. These systems work by providing an internal lining for the basement that is in place to direct water towards a drainage system if it enters through the basement walls. Cavity drainage membranes are classified as Type C waterproofing, and require maintainable, accessible drainage to be set up in order to work at their most effective. Often this is done with a modular drainage system or similar. Along with this, some preparation for the cavity drainage membrane will also be required before the membrane can be installed. This will usually involve treating any brickwork, stonework, and new concrete with an anti-lime treatment that is designed to prevent limescale from forming within the new drainage system.

What is a Drainage Membrane Best Used For?

In many cases, a cavity membrane drainage system is used for refurbishment and conversion projects in existing properties. They are most commonly used for damp proofing and waterproofing before a basement or cellar conversion is carried out. However, they can also be used when constructing new properties to provide peace of mind that there is protection against damp. In some cases, homeowners who are considering this method of damp-proofing a basement or room may need to consider using a combined damp protection method. This will involve using a cavity drainage membrane system along with another type of damp protection such as tanking slurry, which seals the walls, floors, and potentially the ceiling of the basement if needed to prevent moisture from entering the walls at all. The cavity membrane system can then be used in conjunction with this to reinforce the protection and ensure that any moisture that does manage to get through is safely and effectively drained away.

See also
Types of Damp

Cavity Membrane and Damp Proofing – What are the Benefits?

Whether you are converting a cellar into a room or building a new property or structure, there are several benefits of using the cavity membrane system for damp proofing. Some of the main advantages of this method include:

Suitable for Any Property

You can use this system for both new builds and refurbishment projects on older homes. It is ideal for properties that are in a flood risk area or are more susceptible to damp and flooding.

Avoid Structural Damage

When used in the cellar or basement, a cavity membrane system can be an ideal way to prevent further structural damage to a property. Since the water is being drained away from the foundation, it will not only prevent damp occurring inside the basement but also prevent the issues that this can cause inside the home such as mould and wet rot.


A cavity membrane damp proofing system is considered to be one of the most reliable options and is designed to last over the long term. When used in your basement, you can expect it to last for many years, offering reliable protection for your property and your belongings.

A cavity membrane system is an ideal choice for damp proofing a cellar, basement, or other below-ground structure. It works by blocking water from entering through the externals walls and draining it away.

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