What Are The Related Accessories For Gas Barrier Membranes?

When constructing buildings,  particularly on sites where harmful gases such as radon, methane, or carbon dioxide are present,  the installation of gas barrier membranes is essential. These membranes prevent dangerous gases from seeping into the building, helping to maintain a safe environment for occupants. However, to function effectively, these membranes require specific accessories that support their integrity and performance. Let’s explore these essential accessories in straightforward terms.

Sealing and Bonding Accessories

Gas Barrier Tapes

What Are They?

Gas barrier tapes are ultra-strong adhesives used to seal overlaps and joints in gas barrier membranes during construction work. They resemble wide, durable sticky tapes but are specially designed to resist environmental factors such as moisture and gas pressure. Contractors use them to join membrane sheets seamlessly, even on uneven or rough building surfaces.

Why Are They Important?

Gas tapes form a continuous, sealed barrier that blocks harmful ground gases from entering buildings. If they are omitted or applied incorrectly, small gaps may appear, allowing dangerous gases to seep into indoor spaces. These tapes are vital for preventing leaks at critical points, particularly where membrane sheets overlap or meet structural elements such as walls and columns.

Types of Gas Barrier Tapes

Double-sided Tape:This tape is applied between two layers of membrane to bond them securely, even in vertical or awkward positions. Installers press the layers firmly together to secure the membranes without trapping air bubbles or creating folds.

Single-sided Foil Tape:This type is used to seal the exposed outer edge of overlapping membranes and to reinforce the strength of the joint. It also enhances durability, particularly in challenging site conditions or in areas at risk of physical damage.

Additional Tips for Using Gas Tapes

• Always clean the membrane surface before applying the tape to ensure maximum adhesive strength.

• Use a pressure roller to press the tape down firmly and eliminate any trapped air.

• Apply a primer if the surface is dusty, damp, or porous – such as concrete or masonry – to improve adhesion.

• Store the tape in cool, dry conditions to prevent adhesive degradation prior to use.

Gas Barrier Top Hats

What Are They?

Gas barrier top hats are pre-moulded, dome-shaped accessories designed to fit snugly around service penetrations such as pipes or ducts. They resemble a fitted cap that wraps around the pipe, ensuring the gas barrier membranes remain sealed and secure. Installers position them directly over the pipe and fix them to the membrane using gas-resistant adhesive or tape. Top hats are usually made from durable, flexible materials that resist tearing, chemical damage, and movement caused by pipe vibration.

Why Are They Important?

Pipes, vents, and cables often need to pass through gas barrier membranes during construction, and each penetration creates a potential leak point. Top hats seal these gaps, creating a continuous, airtight barrier that prevents radon, methane, or other ground gases from entering the building. Without a properly installed top hat, gas can bypass the membrane and infiltrate the structure through pipe openings.

Top hats also reduce the need for complex on-site cutting or shaping, saving time and minimising installation errors. Their use enhances the overall integrity of the membrane system and supports compliance with stringent gas protection building regulations and standards.

Installation Tips for Top Hats

• Always choose the correct size to match the pipe diameter, ensuring a snug, gap-free fit.

• Use gas-resistant tape or sealant around the flange where the top hat meets the membrane.

• Apply a primer if the surface is dusty or rough to improve adhesion.

• Test the seal after installation to confirm it is airtight and secure.

• Fix the top hat in place without stretching or distorting the membrane beneath it.

  
  

Gas Barrier Corner Units

What Are They?

Gas barrier corner units are pre-formed components designed to seal corners and complex junctions in gas barrier membranes installation, particularly within building foundations. They function like construction puzzle pieces, fitting neatly into tight 90-degree angles or other awkward transitions. Most corner units are made from durable, flexible materials that bond effectively with gas barrier membranes and tapes. They are available in various configurations: internal, external, or universal,  to accommodate different structural layouts on site.

Why Are They Important?

Corners are among the most challenging areas to seal using only flat membrane sheets and tape. When installers attempt to fold membranes into corners, wrinkles and gaps often form, creating potential pathways for gases to escape through. Corner units eliminate this risk by offering a ready-to-fit, airtight solution without the need for manual cutting or folding.

They provide consistency across installations and significantly reduce the likelihood of human error during membrane application. In addition, using corner units speeds up the installation process and helps ensure compliance with gas protection regulations in a more dependable manner.

Installation Tips for Corner Units

• Select internal or external corner units depending on whether the joint faces inward or outward.

• Prime both the membrane and the corner area before installation to enhance adhesion.

• Seal all edges with gas-proof tape or mastic to ensure added security.

• Press the unit firmly into position, ensuring full contact along all edges.

• Avoid stretching or twisting the membrane when connecting it to the corner unit.

  
  

Primer

Primer is a liquid bonding agent applied before tapes, membranes, or sealants to enhance their adhesion. Think of it as a sticky base coat that helps tapes and membranes grip onto surfaces such as concrete, masonry, or metal. It is typically supplied in tubs or cans and can be applied using a roller, brush, or spray, depending on the surface area and site conditions.

Primers are usually quick-drying and specifically formulated to work in conjunction with gas-resistant tapes and membranes, ensuring a reliable and long-lasting seal.

Why Is It Important?

Surfaces such as concrete are often dusty, rough, or porous, which can weaken the bond between membranes and tapes. Primer addresses this by filling surface imperfections and creating a tacky layer that significantly improves adhesion. This helps to prevent lifting, peeling, or the formation of air bubbles – all of which can result in gas leaks and reduced protection.

Applying primer also extends the lifespan of the gas barrier system, particularly in damp or high-traffic areas. Moreover, many building regulations and product manufacturers stipulate the use of primer as a requirement for correct installation and long-term gas resistance.

Application Tips for Primer

• Clean the surface thoroughly: Remove all dust, grease, and moisture before applying the primer.

• Stir well before use: Ensure the primer is properly mixed, then apply an even coat across the entire bonding area.

• Wait for the right finish: Allow the primer to dry until it becomes tacky before applying any tape or membrane.

• Don’t rush the process: Follow the drying time recommended on the product label for optimal results.

• Use safety precautions: Wear gloves and ensure adequate ventilation, especially when working in enclosed spaces.

  
  

Gas Barrier Jointing Strips

What Are They?

Gas barrier jointing strips are rigid plastic or rubber strips designed to seal and reinforce the overlaps between membrane sheets. Think of them as strong belt straps, securing two membrane sections together through a combination of pressure and adhesion. They are typically applied over membrane seams after taping, adding an extra mechanical layer of protection.

Some jointing strips feature a textured surface, enhancing their grip on the membrane when compressed, and improving overall sealing performance.

Why Are They Important?

Seams and overlaps are the most vulnerable points in any gas barrier membranes. Even perfectly taped seams can deteriorate over time due to ground movement, temperature fluctuations, or on-site activity. Jointing strips provide crucial reinforcement, preventing seams from peeling or separating under stress.

They greatly reduce the risk of gas infiltration through overlaps, particularly in high-risk or unstable ground conditions. Incorporating jointing strips enhances the long-term durability of the system and delivers a more robust, professional-grade finish.

Installation Tips for Jointing Strips

• Clean and dry the membrane surface before applying jointing strips to ensure maximum bond strength.

• Apply even pressure along the strip to guarantee full contact and eliminate any trapped air.

• Use compatible adhesive or fixings if recommended by the manufacturer for added security and durability.

• Position the strips accurately typically centred over the seam to fully cover and protect the joint area.

• Do not stretch or bend the strips; they should lie flat to maintain a consistent and effective seal.

  
  

Gas Barrier Sealants

What Are They?

Gas barrier sealants are thick, flexible adhesives used to seal small gaps or irregular surfaces around gas barrier membranes. They function similarly to construction-grade caulk, applied into corners, edges, and tight spaces where tape may not be effective. Sealants adhere to a variety of materials such as concrete, brick, or plastic, and remain flexible to accommodate any movement as the building settles or shifts.

Most sealants are applied using a standard caulking gun and cure to form a tough, rubbery finish that helps maintain an airtight seal.

Why Are They Important?

Even the smallest gap or tear in a gas membrane can allow harmful gases to enter a building. Tapes and membranes alone may not adhere effectively in corners or complex areas, particularly around curves or protrusions. Sealants provide an airtight seal in these challenging zones, reinforcing weak points that may be overlooked during installation.

They are essential for sealing around pipe penetrations, edges, and overlapping joints, helping to prevent long-term system failure. Applying sealant strengthens the overall gas protection system, ensuring it remains effective even under demanding site conditions.

Where to Use Sealants

• Around top hats and pipe entries to block potential gas pathways.

• In corners, junctions, and detailing areas where flat membranes cannot form a smooth, continuous seal.

• Beneath overlaps, providing double protection alongside tape.

• Along perimeter edges where the membrane meets walls, footings, or other structural elements.

• In repair zones, for patching small punctures or areas of minor damage.

  
  

Application Tips for Gas Sealants

• Thoroughly clean the surface, removing any dust, debris, or moisture prior to application.

• Cut the nozzle tip to suit the required bead size for neat and precise application.

• Smooth the bead using a gloved finger or suitable tool to ensure it is firmly pressed into the gap.

• Allow adequate curing time before covering the area or applying any pressure.

Store sealants in a cool, dry place, and always check the expiration date before use.

Protection and Ventilation Accessories

Gas Barrier Protection Boards

Gas barrier protection boards are durable, rigid sheets installed directly over gas membranes to safeguard them from damage during and after construction. Think of them as protective armour, shielding the membrane from sharp tools, heavy machinery, and falling debris.

These boards are typically made from materials such as high-density polyethylene (HDPE), bitumen-coated board, or rigid insulation panels. They are available in various thicknesses, selected according to the level of site traffic and the potential risk of puncture.

Why Are They Important?

Construction sites are high-traffic environments, with constant movement of equipment, tools, and personnel. Without protection boards, the gas membrane beneath is vulnerable to tearing, puncturing, or peeling, all of which can create dangerous pathways for gas to enter the building.

Even a small tear can compromise the entire gas protection system and result in costly remedial work. Protection boards help preserve the membrane’s integrity during key construction phases such as backfilling, concrete pouring, or floor slab installation. By installing these boards, you ensure that the gas barrier remains effective long after the build is complete.

Installation Tips for Protection Boards

• Lay protection boards immediately after the membrane is installed to minimise the risk of accidental damage.

• Slightly overlap the boards to eliminate gaps that could expose the membrane beneath.

• Use temporary fixings or weighted materials to hold the boards in place, particularly in windy or high-traffic site conditions.

• Secure boards on vertical surfaces with mechanical fasteners or a compatible adhesive, as appropriate.

Select the board type based on anticipated site activity – heavier traffic areas require thicker, more robust protection boards.

Ventilation and Gas Extraction Systems

What Are They?

Ventilation and gas extraction systems are engineered solutions designed to safely divert harmful gases away from buildings before they pose a threat. These systems typically include components such as perforated pipes, vertical vents, manifolds, and, in some cases, mechanical fans for active extraction.

You can think of them as underground exhaust systems, drawing gases from beneath the structure and venting them safely into the open air. Depending on the gas risk level of the site, these systems are installed either below the gas membrane or beneath the building’s foundation.

Why Are They Important?

Gas membranes act as a protective shield, but they do not remove the build-up of gases beneath a structure. Without adequate ventilation, harmful gases such as radon and methane can accumulate beneath the membrane, creating pressure that may compromise its integrity.

Ventilation systems alleviate this pressure by providing a controlled escape route for gases, allowing them to disperse safely before reaching the membrane. These systems are particularly vital in high-risk areas, where gas concentrations may exceed safe limits or fluctuate over time.

Combining gas membranes with effective ventilation significantly enhances protection and helps ensure compliance with environmental and health and safety regulations.

Types of Ventilation Systems

Passive Systems:Utilise natural air flow through vent pipes to disperse gases without relying on electrical components. These are low-maintenance and suitable for sites with lower gas risk levels.

Active Systems:Incorporate fans or blowers to actively extract gases from beneath the building. These are used when passive systems are insufficient, especially in high-risk areas.

Radon Sumps:Small collection chambers installed beneath the foundation and connected to vent pipes. They target specific areas for focused gas removal, particularly effective against radon.

Vent Mat Systems:Provide a continuous air path beneath the membrane, allowing gases to move freely towards designated extraction points. These are ideal for creating uniform ventilation across large floor areas.

Installation Tips for Ventilation Systems

• Position vent pipes within gravel layers or geocomposite mats to maximise gas collection coverage beneath the structure.

• Ensure vent outlets terminate safely above ground level and are located away from windows, doors, or air intakes to prevent re-entry of gases.

• Use robust, perforated piping and suitable backfill materials to prevent crushing, blockages, or system failure over time.

• Test airflow after installation to confirm that gases can move efficiently through the system.

• Schedule regular inspections and maintenance, particularly for systems with mechanical fans or active extraction components.

  
  

Conclusion

Gas barrier membranes alone are not sufficient to fully protect a building from harmful ground gases without the correct supporting accessories. Components such as tapes, top hats, corner units, sealants, and ventilation systems are essential for sealing potential weak points and ensuring an airtight, reliable performance.

Each accessory enhances the integrity of the system by preventing leaks at overlaps, service penetrations, and complex junctions. Protection boards safeguard the membrane from physical damage during construction, while ventilation systems relieve pressure build-up beneath the structure.

Omitting any of these elements can result in gas ingress, safety hazards, or expensive remedial works. Always use high-quality, compatible products and adhere to proper installation procedures. A well-sealed gas protection system not only preserves the structure but also safeguards its occupants. Start with precision, seal every detail, and build confidence into your project from the ground up.

FAQs

Can I install gas barrier membranes and accessories myself?

Professional installation is strongly recommended. It ensures correct sealing, proper detailing, and compliance with building regulations and safety standards.

Are accessories universally compatible with all gas membranes?

No. Not all accessories are interchangeable. Some are designed to work only with specific membrane types. Always refer to the manufacturer’s guidelines before purchasing or installing any components.

Is primer really necessary for gas membrane installation?

Yes. Primer significantly improves adhesion on rough, dusty, or porous surfaces. It helps prevent tape or membrane failure and enhances the overall integrity of the system.

How long do these gas protection systems last?

When correctly installed and protected from physical damage, gas protection systems can last for decades, providing long-term safety.

Do gas protection systems require any maintenance?

Yes. Periodic inspection is advisable, particularly for systems with mechanical ventilation components. Regular maintenance ensures continued performance and compliance over time.