Can You Use Roofing Membrane on Walls?

Roofing membranes are a staple of modern roof systems. They’re breathable, waterproof, and essential for protecting the structure beneath your tiles or slates.

But we often get asked a less common question at Roofing Newcastle:

Can you use roofing membrane on walls?

The answer is yes—in some cases. But it depends on the application, the building design, and whether the membrane is suitable for vertical use.

Let’s explore when and how roofing membranes can be used on walls, and whether it’s a good idea for your project.

What Is Breather Membrane?

Roofing membrane (often called underlay or breather membrane) is a thin, synthetic layer installed beneath roof tiles or slates. These are also commonly referred to as roofing underlays. Its job is to:

• Allow moisture to escape from inside the property (breathability)
• Stop water from penetrating the roof structure
• Add a second layer of weather protection

Modern membranes are typically vapour-permeable but waterproof, making them ideal for both pitched roofs and certain wall applications.

What is a Breather Membrane?

A breather membrane, also known as a breathable membrane, is a specialised building material designed to allow water vapour to escape from within a structure while preventing external moisture and air from penetrating. This dual functionality makes it an essential component in modern wall construction, particularly in regions with high humidity or frequent rainfall. Breather membranes are typically used alongside insulation materials to create a comprehensive weatherproofing system that enhances the durability and energy efficiency of buildings. Available in various forms, including non-woven, woven, and coated membranes, each type offers unique characteristics and benefits tailored to specific construction needs.

Can Roofing Membranes Be Used on Walls?

Yes—but only certain types of roofing membranes are suitable for vertical application.

Some roofing membranes are dual-purpose and can be installed on:

• Timber-frame external walls
• Cavity walls
• Behind cladding systems
• In SIP (structural insulated panel) construction
• In garden rooms or outbuildings

These membranes act as a weather-resistant barrier, keeping wind and water out while allowing the structure to breathe.

However, not all membranes are rated for use on vertical surfaces. That’s why it’s important to check the product specifications—or speak to an expert.

At Roofing Newcastle, we always check compatibility before using roofing products in non-standard ways.

Types of Membranes for Walls

When it comes to wall applications, several types of membranes are available, each with distinct advantages. Non-woven membranes, such as Tyvek, are crafted from polyethene fibres and are highly breathable, making them ideal for timber frame walls. Woven membranes, like ProClad, are made from polyester or polypropylene fibres, offering enhanced durability and resistance to tearing. Coated membranes, such as Siga, feature a waterproof coating on one side and a breathable layer on the other, providing robust protection against external moisture while allowing internal vapour to escape. The choice of membrane should be based on the specific requirements of the project, including the type of wall, local climate conditions, and the desired level of breathability.

When Is It a Good Idea?

Here are a few examples of where roofing membranes on walls makes sense: Using roofing membranes on walls can provide several benefits, including enhanced thermal insulation, moisture control, and overall durability.

1. Timber Frame Walls Construction

Breathable membranes are often used on the outside of timber frames and timber-framed walls, behind the external cladding or brickwork. They protect the insulation and frame from moisture while allowing vapour to escape.

2. Cladding Systems

Membranes are also used behind timber, composite, or metal cladding systems to prevent wind-driven rain or water ingress. While these membranes are effective behind cladding systems, they are also commonly used in pitched roof applications for their breathability and water resistance.

3. Garden Rooms and Sheds

If you’re building a garden office or workshop, using roofing membrane on the walls adds a breathable layer of protection—especially when insulation is added inside.

4. Renovation Projects

In older properties with solid walls, breathable membranes may be used internally before installing insulation systems, to help manage moisture and prevent damp issues.

What Are the Benefits for Energy Efficiency?

• Moisture Control: Prevents condensation buildup in walls
• Water Resistance: Stops rainwater from entering the structure
• Wind Barrier: Improves airtightness and thermal performance
• Lightweight: Easy to install and cut to shape
• Cost-effective: Adds protection without major expense

These benefits are not only applicable to wall systems but also to pitched roof applications, where similar principles of moisture control and breathability are crucial.

Membrane Installation Considerations

Proper installation of a breather membrane is crucial to its effectiveness in preventing moisture buildup and maintaining energy efficiency. The membrane should be installed on the exterior of the wall, with the breathable side facing outwards to allow water vapour to escape.

It is essential to securely fasten the membrane to the wall using appropriate staples or nails, ensuring that overlaps are consistent with building regulations to prevent any gaps. Additionally, the membrane should be promptly covered with external cladding to protect it from UV degradation and maintain its durability and functionality. Following these installation guidelines helps ensure that the breather membrane performs optimally, contributing to the overall integrity of the wall system.

Air Tightness and Moisture Control

A breather membrane plays a pivotal role in maintaining air tightness and moisture control within a building. By allowing moisture to escape while preventing air and water from entering, the membrane helps to prevent condensation buildup, reducing the risk of mould and rot. This not only contributes to a healthier indoor climate but also enhances the building’s energy efficiency by minimising heat loss and preventing cold air infiltration. The result is a more comfortable living environment and lower energy bills, making breather membranes a valuable addition to any wall system.

Are There Any Risks?

Yes—if the wrong membrane is used or it’s installed incorrectly.

Common issues include:

• Trapping moisture: Using a non-breathable membrane on a wall can cause dampness or rot inside the structure
• UV degradation: Some membranes aren’t UV-stable and will break down if exposed to sunlight for too long before being covered
• Fire rating: Membranes used on external walls in certain buildings (especially flats or high-rises) may need to meet strict fire performance standards
• Not meeting building regs: Using roofing materials in wall systems without following approved details may cause issues with Building Control

That’s why you should always speak to a qualified installer or supplier before going ahead.

Do Building Regulations Allow It?

In most cases, yes—but only if the membrane is designed and certified for wall use.

Approved membranes will have documentation (like a BBA certificate) that lists where they can be used—on roofs, walls, or both. Using a roof-only product on a wall without that certification may not pass inspection.

If you’re building an extension, garden room, or cladding system, your building control officer may ask for product data to confirm compliance.

We handle this for our customers at Roofing Newcastle to keep your project moving smoothly.

Choosing the Right Membrane

Selecting the right breather membrane for your project involves considering several key factors, including the type of wall, local climate, and the desired level of breathability. It’s important to choose a membrane that offers the right balance of breathability and durability, ensuring it can withstand the specific conditions of your project. Compatibility with other building materials is also crucial to ensure seamless integration into the wall system.

Additionally, make sure the membrane is certified to relevant building standards, such as BS 5534:2014, and that it is installed correctly to maximise its effectiveness. By carefully selecting and installing the appropriate breather membrane, you can enhance the performance and longevity of your building.

Final Thoughts

So—can you use roofing membrane on walls?

Yes, you can—but only if the membrane is suitable for vertical application and installed correctly.

When used properly, a roofing membrane can add valuable water resistance, wind protection, and breathability to wall structures—especially in timber-frame buildings and cladding systems.

If you’re unsure which membrane to use or whether it’s right for your project, contact Roofing Newcastle today. We’ll advise you on the best solution and ensure it meets all safety and building regulation requirements.

Protect your roof. Protect your walls. Do it right the first time.