The safety of your construction project and well-being of its future occupants are paramount, but it is not just about protecting the structure from water ingress. If ground gases are present on the site, such as methane, radon, and CO2, these need robust gas protection systems, as these gases could seep into the building and damage the health of the residents.
Contaminated land may also contain hydrocarbons and volatile organic compounds (VOCs), which our systems are designed to mitigate.
Our range of gas and VOC protection systems are meticulously engineered to meet the strictest safety standards, providing dependable defence in combination with waterproofing or damp proofing.
Premcrete offer end-to-end support, from feasibility studies to installation guidance, with the added benefit of design liability covered by our £10M professional indemnity insurance, which takes the pressure away from architects, structural engineers and main contractors.
Our membranes are designed to selectively permit the passage of certain gases while blocking others, controlling and slowing the flow of gases and compounds through the structure. Each membrane possesses distinct qualities, which is why we categorize them accordingly. Here are some types of gas protection systems manufactured in the UK:
Our DPM-grade gas membranes provide dual protection against ground gases like radon, methane and moisture ingress. Made from high grade materials, these membranes meet stringent standards for both gas impermeability and moisture resistance. Ideal for scenarios susceptible to dampness and gas, they ensure a safe, healthy indoor environment and maintain structural integrity.Examples of these membranes are Hydroprufe 9000, or our more robust version - Hydroprufe 6000 - a DPM that protects against gas, VOCs and moisture.
Whether pre-applied or post applied, combined protection is utilised in many of our projects. This dual functionality is especially valuable in areas with high groundwater levels or contaminated sites, where both water ingress and gas infiltration are significant risks.
Installing a single, multifunctional membrane is more cost-effective than implementing separate systems for waterproofing and gas protection. It reduces both material and labour costs, simplifying the construction process.
Our fully bonded pre-applied membranes include Combiseal and Combiseal-Plus, or an example of a post applied self-adhesive membrane is Hydroprufe 8000, often installed at the slab edge detail building perimeter, but also used to waterproof the outside of a double sided concrete wall, prior to backfilling with earth.
Epoxy-based liquid gas membranes are suitable for application to porous substrates to provide resistance to gases. When applied to the substrate, such as a pile cap or pile head, a liquid membrane provides continuity of protection where a loose laid or pre-applied membrane can't be applied.
A commonly used example of Premcrete's liquid gas protection system is Hydroprufe LG, which has a quartz stone additive broadcasted into it to replicate the concrete to concrete bond required, and meet the coefficient of friction test standards.
Applying gas protection at service penetrations is crucial for preventing hazardous gases such as methane or radon from infiltrating buildings, because a penetration disrupts the continuity of protection across a floor slab, wall or foundation.
Effective solutions include gas-resistant sealants that provide a durable and flexible seal, along with collars, sleeves and specialist ancillary tapes that create physical barriers around penetrations.
Ventilation mats provide a void to allow for the dispersion of ground gases, which may collect beneath a structure. These are known as passive ventilation systems.
The Premcrete Hydrovoid system works by creating a void beneath the building's foundation or slab, providing a pathway for gases to move freely and be vented out safely above the structure, or at the perimeter of the building footprint.On projects with higher levels of radon, active ventilation is sometimes required, which involves the installation of a fan connected to a pipe system that extends from beneath the foundation of the building. The fan actively draws radon-laden air from beneath the building and expels it outside.
BS 8485:2015+A1:2019 – Codes of Practice for Protective Measures Design Against Methane and Carbon Dioxide Ground Gases in New BuildingsGround gases are commonly associated with landfill sites but can also emanate from various other sources. The standard emphasizes the importance of employing qualified installers for these protective systems. Compliance with Ciria C735 is essential for validation. It is also crucial to consider additional factors that may affect the system, such as hydrostatic conditions and the potential for direct contact between the source contaminant and the proposed protective measures.
BRE 211:2015 – Guidance on Protective Measures for New Buildings (RADON)Radon, a naturally occurring ground gas, is found in larger concentrations in the South West of the UK. The guidance stipulates a minimum requirement of a 300 micrometre (1200 gauge) polyethylene sheet or equivalent membrane. This membrane must be meticulously installed, carefully protected post-installation and include taped laps to ensure effectiveness.
CIRIA C748:2014 – Guidance on the Use of Plastic Membranes as VOC Vapour Barriers CIRIA C682:2009 – VOC HandbookThis guidance adopts a risk-based approach and does not establish quantifiable limits on material performance. It requires testing in accordance with ISO 15105-2 and EN 14414/EN 14415, covering nine main types of Volatile Organic Compounds. Welded laps are necessary for the installation as most tapes, commonly made from bitumen or butyl, are affected by VOCs.
CIRIA C735:2014 – Good Practice on Testing and Verification of Protection Systems to Buildings from Hazardous GasesThis guide outlines good practices for testing and verifying protection systems designed to shield buildings from hazardous gases. It includes checking that design and detailing align with site-specific requirements, verifying the competency of the installer (minimum NVQ Level 2 required). BS8102:2022 – Code of Practice for Protection of Below Ground Structures Against Water from the GroundReferring to BS8102:2022 when designing gas protection systems is crucial because it ensures that structural protections against water also safeguard against gas infiltration.Adhering to this standard helps maintain structural integrity, ensures regulatory compliance, and leverages best practices for material and system compatibility, enhancing the overall safety and effectiveness of the protection systems.
Installing gas membranes to a high standard is crucial for shielding buildings from harmful gases like radon, methane and CO2.
The process begins with preparing the site to ensure a smooth, clean base often involving a layer of sand or geotextile to prevent membrane punctures.
The membrane is then laid out with significant overlap for a continuous barrier and the seams are sealed – either by welding or taping.
Welding involves using heat to fuse the membrane material together at the seams, creating a durable, monolithic barrier ideal for high risk areas in particular. This also requires installation by NVQ level 2 (minimum) qualified membrane installers.
Taping is simpler and faster to apply than welding, and does not require special equipment or extensive training, therefore presenting a “self-install” option for groundworkers or other contractors who are not necessarily specialist installers.
At Premcrete our membranes are supplied as a taped solution as standard, but welding is a prerequisite by the warranty provider, our membranes can be supplied in weldable format.
After installation, it is essential to protect the integrity of the membrane with a protection board, such as Premcrete’s Protection Board 300 (lightweight) or Protection Board 600 (heavy duty). The boards guard against damage from construction activities and backfill material, ensuring the membrane’s effectiveness over time.
Third party verification is crucial for ensuring gas membranes and protection systems meet safety standards like BS 8485:2015+A1:2019 and CIRIA 735.
Companies such as GeoShield and Membrane Testing Services provide independent verification to confirm installations are effective against hazardous ground gases.
Involving third party verifiers ensures compliance with safety guidelines and helps prevent gas ingress, enhancing construction safety. This verification is often mandatory, reflecting the industry’s emphasis on reducing risks associated with ground gas infiltration, thus safeguarding life and property.
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