What Is The Correct Way To Install Gas Barrier Membranes?

Installing gas barrier membranes is a vital phase in building construction, particularly in areas where harmful ground gases may be present. Gas barrier membranes are essential for preventing harmful gases like Radon and methane from entering indoor spaces. Proper installation ensures long-term protection and keeps your build safe and compliant with UK regulations. In this guide, we’ll walk you through the process step by step, using the appropriate building materials and construction accessories to help you install with accuracy and confidence.

Understanding Gas Membranes: What You Need to Know

Gas membranes are protective sheets designed to prevent harmful gases from entering buildings via the ground. These sheets are typically installed during the early stages of construction, positioned beneath the floor or incorporated within the foundation layers. Their main role is to block hazardous gases such as radon, methane, and carbon dioxide from penetrating indoor spaces. By creating a gas-tight seal beneath the structure, gas membranes play a vital role in maintaining the overall safety and integrity of a building. A range of types is available on the market, each tailored to different site conditions and construction requirements.

Why You Should Use a Gas Membrane

Gas membranes safeguard buildings from harmful ground gases that can rise through the soil and enter indoor areas. Without proper protection, these gases can accumulate and degrade air quality, presenting serious health risks over time. 

Common hazardous gases include:

• Radon – radioactive and associated with lung cancer

• Methane – flammable and explosive

• Carbon dioxide – displaces oxygen in enclosed spaces 

These gases are invisible and odourless, making them difficult to detect. A gas membrane serves as a vital barrier, preventing gases from penetrating the building.

That is why gas membranes have become standard in:

• New builds

• Extensions and conversions

• Projects near contaminated land

Installing a membrane at the early stages of construction ensures lasting safety. It protects everyone who lives or works in the building. Opting for a gas membrane is a wise and essential safety measure.

When Is a Gas Membrane Needed?

Gas membranes are vital on sites where there is a significant risk of underground gases. To determine whether your site is at risk, you will need a professional gas report. These reports assess soil conditions and gas concentrations, helping you understand if protective measures are required before construction commences.

The primary guideline for gas protection in new buildings is BS 8485:2015. This standard addresses the risks of gases such as methane and carbon dioxide, which are commonly found in areas with a history of industrial use or landfill activity. It outlines essential steps including site investigations and continuous gas monitoring, and also assists in designing suitable protection systems based on the gas levels detected.

If you are located in a radon-prone area, a radon barrier is also necessary. Radon is a naturally occurring radioactive gas that can cause serious health problems over time, including lung cancer. You can check for radon risk using data from the British Geological Survey, which provides detailed maps and reports based on reliable national data. These follow the BR211 guidance, which supports safe construction practices in radon-affected regions. Existing homes can also be tested for radon levels using specialist detectors.

Gas membranes are not solely for large or commercial developments. They should be considered for all new builds, home extensions, and property conversions. Basement conversions, in particular, carry higher risk due to their direct contact with the ground. Fitting a gas membrane in such projects adds an essential layer of protection and delivers long-term peace of mind.

Types of Gas Membranes

There are several options available when selecting a gas membrane. Common types include radon barrier membranes, liquid-applied systems, and self-adhesive gas-proof sheets. Another widely used option is the gas damp-proof course (Gas DPC), which offers similar protection against harmful gases. Some of these membranes also perform dual functions by acting as moisture barriers, providing both gas resistance and damp-proofing benefits. Opting for a dual-purpose membrane can help lower overall material costs while simplifying the installation process. However, not all sites are suitable for a single-layer solution. Specific conditions may demand additional protective measures.

When to Add Extra Protection

In locations where groundwater pressure is elevated or where water tends to accumulate underground, standard gas membranes may not offer adequate protection. In such cases, specialists often advise the installation of a cavity drainage system. This system manages the movement of water around the foundation, safely diverting it and minimising the risk of long-term structural damage. It operates in conjunction with the gas membrane to provide a more robust barrier against environmental hazards.

How to Choose the Right Membrane

Choosing the appropriate gas membrane depends on several factors specific to your project. The type of soil, levels of ground gases, and water pressure on-site all influence which product is most suitable. It is always advisable to consult a qualified building professional to ensure your membrane selection complies with safety standards and building regulations. Correct selection and installation of a gas membrane help to ensure long-term protection and peace of mind. Planning your gas barrier system early can help avoid costly remedial work and serious structural problems later on.

The Benefits of Gas Membranes in Construction and Environmental Safety

Gas membranes play a vital role in contemporary construction practices. They protect homes, commercial buildings, and infrastructure from invisible yet serious environmental hazards. When correctly installed, they function as multi-purpose barriers against gases, moisture, and even air movement. Their benefits extend across health protection, regulatory compliance, durability, and energy performance.

Radon Gas Protection

Radon is a naturally occurring radioactive gas found in certain soils and rock formations. In the UK, many regions—particularly those underlain by granite or limestone—are designated high radon zones. Radon can migrate through the ground and enter buildings via cracks and joints. Indoors, it may accumulate to hazardous levels without adequate ventilation or barrier systems. Prolonged exposure to radon is the second leading cause of lung cancer. It presents a serious health risk, especially in poorly ventilated spaces or basement areas. Gas membranes provide a continuous seal beneath a building’s foundation. This barrier effectively prevents radon infiltration and build-up within the property. By stopping this gas at its source, gas membranes help create healthier indoor environments and safeguard long-term health.

Compliance with Building Regulations

UK Building Regulations stipulate the need for radon protection in radon-affected areas. This requirement applies to new builds as well as certain extensions and refurbishments. Guidelines issued by the National House-Building Council (NHBC) and the Property Care Association endorse the use of gas membranes. Their recommendations assist builders and developers in adhering to relevant safety legislation. Installing a certified gas membrane ensures your project meets current standards. It also offers reassurance to homeowners, surveyors, and developers. In many cases, incorporating a gas membrane is not merely best practice—it is a statutory obligation.

Moisture Control and Vapour Resistance

Beyond gas protection, many membranes also function as vapour control layers. These manage rising ground moisture entering the structure. Moisture ingress is a significant concern in the UK’s damp climate. It can lead to mould, timber decay, and damage to interior finishes and fittings. By forming a sealed layer beneath floors and walls, gas membranes prevent moisture intrusion. This preserves building materials and supports a healthy, mould-free living environment. Moisture control is particularly critical in ground floors and basements. Membranes reduce condensation and enhance indoor air quality.

Energy Efficiency and Climate Control

Some gas membranes also serve as air barriers. They limit unwanted airflow between the ground and the internal environment. This enhances insulation and helps maintain consistent indoor temperatures throughout the year. During winter, they retain warmth; in summer, they help prevent overheating. This leads to reduced energy demand for heating and cooling. In turn, this results in lower utility costs and reduced carbon emissions. These properties contribute to making buildings more energy-efficient, environmentally friendly, and economical to operate.

Long-Term Building Durability

Gas membranes also defend structural components from environmental wear and tear. By obstructing gases and moisture, they minimise risks of corrosion, timber rot, and other degradation. Materials such as insulation, concrete, and timber last significantly longer when shielded from aggressive ground conditions. This extends the structure’s lifespan and limits the need for costly maintenance. Over time, gas membranes offer excellent return on investment. They protect both the building’s integrity and reduce future repair demands.

Gas membranes are a prudent investment in health, safety, and structural longevity. Whether for new homes, extensions, or commercial developments, their advantages are enduring and essential.

How Safe Are Gas Membranes?

Gas membranes are extremely safe when they comply with approved standards and are installed correctly. Membranes with BBA certification undergo stringent testing to verify their performance and reliability. These assessments evaluate the membrane’s ability to block harmful ground gases and test its durability under construction and environmental conditions.

For instance, the 1200 gauge radon membranes are highly regarded for their strength and superior puncture resistance, making them well-suited for challenging construction projects. These membranes are designed to last for the lifespan of the structure and function reliably under standard conditions without the need for replacement.

Each membrane roll is individually labelled for traceability, ensuring that every batch adheres to strict quality assurance procedures. Accreditations such as BBA and ISO 9001 confirm the product has undergone independent testing and approval processes.

Builders and installers can trust these materials for safety and consistent performance. When installed correctly, certified gas membranes provide complete protection from ground gases. For any new build or extension, selecting a certified membrane ensures long-term safety and peace of mind.

Gas Membrane Installation: What You Need to Know

Correct installation of gas membranes is vital for protecting buildings against hazardous ground gases. When properly fitted, these membranes block harmful substances such as radon, methane, and carbon dioxide from entering internal spaces. However, poor installation can result in leaks, thereby compromising health and safety.

To ensure effectiveness, gas and radon membranes must comply with strict building regulations and recognised standards. Always follow official guidance throughout the planning and construction stages to guarantee full compliance.

These membranes are most commonly used in concrete ground floor systems and can be installed either:

• Above the concrete slab

• Below the concrete slab

The appropriate positioning depends on your building’s design and ground conditions. For this reason, early planning is crucial, particularly on high-risk sites. Incorporating gas protection measures during the structural design phase ensures the installation is both accurate and effective.

Gas membranes are frequently used in the following floor constructions:

• Reinforced cast in-situ concrete floors

• Suspended beam-and-block concrete floors

• Precast concrete slabs

Each of these systems may require a different installation technique, so it is essential to consult professionals experienced in gas membrane systems. Proper positioning not only ensures long-term safety and regulatory compliance but also contributes to the building’s durability and future resale value.

Radon Gas Barrier Membranes Installation: A Step-by-Step Guide

Installing a radon gas membrane is a crucial component of any gas protection system. It blocks hazardous gases such as radon from entering your home or building. For the barrier to be effective, it must be installed correctly and in accordance with building regulations. Poor installation may allow gases to pass through, posing significant health risks.

Before You Begin

Ensure the radon membrane covers the entire floor and wall area. Even small gaps in coverage can permit radon ingress into the structure.

Important: Radon membranes are not suitable for areas with hydrostatic water pressure. In such cases, a cavity drainage membrane system should be used instead.

Step 1: Prepare the Surface

Unroll the first membrane on a smooth or sand-blinded surface.

Check for sharp objects, indentations, or rough patches that might cause punctures.The surface must be clean, dry, and free from grease to ensure a proper seal.

Gas Membrane Jointing

All joints must be thoroughly sealed, including corners and beneath walls. Effective sealing is essential for creating a gas-tight barrier.

Step 2: Apply Double-Sided Tape

Apply Double-Sided Tape 50mm from the edge of the membrane.

Leave the backing paper in place for now.

This tape is critical for ensuring gas- and water-tight joints.

Step 3: Overlap and Seal the Next Membrane

Unroll the second membrane and ensure an overlap of at least 150mm.

Ensure both membrane sheets are dry, clean, and dust-free.

Remove the backing from the tape and press the membranes firmly together.

Apply even pressure to ensure a strong, gas-tight seal.

Every overlap must be sealed using this double-tape method.

Step 4: Seal the Top Edge

Apply single-sided gas tape along the top edge of the overlap.

This produces an airtight finish and prevents screed from entering the joint.

It also secures the membrane in place before the floor is poured.

Sealing Around Pipes and Penetrations

• Cut an opening in the membrane that closely fits the pipe diameter.

• Insert the pipe and install a top hat fitting over the penetration.

• Use gas tape to seal the base of the top hat to the membrane thoroughly.

• This prevents radon gas from escaping around the pipe junction.

Protecting the Radon Membrane

Once installed, the membrane is prone to damage. Even a small tear or puncture compromises its performance.

To protect it:

• Cover with temporary protective boards before the flooring is laid, or

• Pour the screed immediately after installation.

Floor and Wall Joints

Every floor-to-wall joint must be completely gas-tight.

Pay close attention to corners, areas beneath walls, and connections to gas damp-proof courses (DPCs).

Note: Diagrams and technical detail drawings are useful, but always consult your project designer. Final specifications must be tailored to your specific site and construction design.

Choosing a Radon Barrier Installer

To select a reliable installer:

• Seek recommendations from friends or trusted local builders

• Check independent review sites such as Checkatrade, Trustpilot, and Reviews.co.uk

• Meet several installers and compare quotes and services

• Use this guide to ask relevant, informed questions during consultations.

Ventilation and Full Gas Protection Systems

Gas membranes are just one part of a comprehensive gas protection solution. Effective ventilation is essential to prevent gas build-up beneath the floor.

Typical ventilation methods include:

• Ventilation layers and air bricks for natural airflow

• Fans and radon sump systems for active ventilation

A radon sump is often used to draw gas away from beneath the building, working similarly to a basement sump pump but specifically for gas extraction.

In larger commercial premises, active gas protection systems are required. These use electromechanical components to enhance ventilation and maintain safe internal conditions.

Note: For the best results, consult a qualified professional alongside reputable building suppliers to design the right system for your project.

Conclusion

Installing gas barrier membranes properly is essential for protecting buildings from hazardous ground gases such as radon and methane. In the UK, regulations like BS 8485:2015 and BR211 set the standards for safe and compliant installations. Using certified products, such as BBA-approved membranes, and following precise sealing methods ensures long-term protection and peace of mind. Failure to install membranes correctly risks non-compliance, health hazards, and expensive remedial work. Always plan early, especially on high-risk or brownfield sites, and integrate ventilation systems where required. Whether you’re building a new home, extension or basement, gas protection must be part of your foundation strategy. Act now to secure a safer, regulation-compliant future for your property—start from the ground up.

FAQs

What do gas membranes protect against in the UK?

They block ground gases like radon, methane, and carbon dioxide from entering buildings through the substructure.

Are gas membranes a legal requirement in the UK?

Yes, in radon-affected areas or where BS 8485:2015 risk assessments indicate gas protection is needed.

Where are gas membranes typically installed?

They are placed beneath ground floor slabs or within foundations during the early stages of construction.

How should gas membranes be sealed?

Use approved gas tapes and follow NHBC or BR211 guidance for airtight, regulation-compliant jointing.

Can I install a gas membrane without professional help?

It’s possible, but consulting a qualified installer ensures compliance with UK regulations and avoids costly mistakes