The A. Proctor Group has been in the Gas Protection market for the past 15 years promoting a range of gas membranes and venting components for use on contaminated land sites. Adequate protection against the ingress of ground gas and vapours is crucial and the A. Proctor Group can provide safe, cost effective and value engineered solutions.
Our technical services include CAD details and project specific recommendations utilising the latest guidance and in full compliance with current legislation and standards.
Ground Gas Protection Brochure
Protech GM Super
|Roll Length||50 m|
|Methane Permeability||ISO 15105-1||≤ 0.1 (ml/day/m2)|
|Roll Length||50 m|
|Tensile Strength||EN ISO 10319||18 kN/m|
|Gas Flow Capacity||0.07 m3/s|
|Compressive Strength||300 kN/m2|
Protech VOC Flex
|Roll Size||-||50 x 2 m|
|Weight||ISO 536||564 gsm|
|Tensile Strength||EN 12311-1||MD 700 / CD 640 N/50mm|
|Elongation||EN 12311-1||MD 30% CD 25%|
|Nail Tear Resistance||EN 12311-1||MD 500 / CD 540 N|
|Methane Permeability||ISO 15105-1||≤0.1 ml/m2/day|
|Determination of Chemical Resistance||EN 14414 Methods A-D||Pass - No visual degradation|
|Resistance to Naphthalene||ISO 15105-2 (EN 14414 Method C)||Pass|
|Resistance to Benzene||ISO 15105-2 (EN 14414 Method C)||Pass|
|Resistance to Toluene||ISO 15105-2 (EN 14414 Method C)||Pass|
|Resistance to Hexane||ISO 15105-2 (EN 14414 Method C)||Pass|
Protech Radon 400
|Roll size||2 x 50 m|
|Thickness||EN 1849-2||0.43 mm|
|Weight||EN 1849-2||400 g/m2|
|Sd value||EN 1931||290 m|
|Resistance to static loading||EN 12730 method B||20 kg|
|Water tightness||EN 1928:2000, Method A (2kPa Pressure)||W1|
|Against heat ageing (EN 1296)||EN 1928:2000, Method A (2kPa Pressure)||W1|
|Against chemicals (EN 1847)||EN 1928:2000, Method A (2kPa Pressure)||W1|
|Tearing strength - MD||EN 12310-1, mod with EN 13859-1:2010 Annex B||320 N|
|Tearing strength - CD||EN 12310-1, mod with EN 13859-1:2010 Annex B||330 N|
|Tensile strength - MD||EN 12311-1, mod with EN 13859-1:2010 Annex A||385 N/50 mm|
|Tensile strength - CD||EN 12311-1, mod with EN 13859-1:2010 Annex A||295 N/50 mm|
|Elongation - MD||EN 12311-1, mod with EN 13859-1:2010 Annex A||20 %|
|Elongation - CD||EN 12311-1, mod with EN 13859-1:2010 Annex A||17 %|
|Foldability at low temperature||EN 495-5||Pass -45 °C|
|Radon transmittance||SP method||1.4.10-8 m/s|
|Radon permeability||SP method||6.0.10-12 m2/s|
- Protech GM Super - CAD - Detail - Raft Masonry
- Protech GM Super - CAD - Detail - Raft Timber Frame
- Protech GM Super - CAD - Detail - Below Raft Masonry
- Protech GM Super - CAD - Detail - Below raft timber frame
- Protech GM Super - CAD - Detail - Suspended slab masonry
- Protech GM Super - CAD - Detail - Beam Block Masonry
- Protech GM Super - CAD Detail - Suspended Slab Timber Frame
- Protech VOC Flex - CAD - Detail - Raft Masonry
- Protech VOC Flex - CAD - Detail - Raft Timber Frame
- Protech VOC Flex - CAD - Detail - Suspended Slab Timber Frame
- Protech VOC Flex - CAD - Detail - Suspended slab masonry
- Protech VOC Flex - CAD Detail - Beam Block Masonry
- Protech Radon 400 - CAD - Detail - Raft Masonry
- Protech Radon 400 - CAD - Detail - Raft Timber Frame
- Protech Radon 400 - CAD - Detail - Below raft masonry
- Protech Radon 400 - CAD - Detail - Below raft timber frame
- Protech Radon 400 - CAD - Detail - Suspended slab masonry
- Protech Radon 400 - CAD - Detail - Suspended Slab Timber Frame
- Protech Radon 400 - CAD - Detail - Beam Block Masonry
CAD Detail Review
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National Technical Sales Manager Ground Gas Protection
07817 872 681
Ground Gas Protection FAQs
How do I select the correct membrane for my site?
The main considerations for choosing the correct gas membrane are the range of gases present on site and the volume flow rate of those gases. As long as a site investigation or ground gas monitoring has been carried out, we are able to determine the level of risk in accordance with BS 8485 for carbon dioxide and methane gases, and BR 211 for radon. The type of membrane installed is also heavily influenced by the level of hydrocarbon contamination in the ground, such as on brownfield sites, which would require a higher level of protection and VOC resistance. Our range includes gas membranes appropriate for all situations and we recommend sending the relevant site information to our technical team for the correct specification and installation instructions.
Can anyone install a gas membrane?
CIRIA C735, the good practice document on verification of gas protection systems, recommends installers should be experienced and qualified to NVQ Level 2 Gas Membrane Installation as a minimum. It is not a requirement for all operatives on site to hold this qualification but installations carried out by others would require a more onerous and intensive verification process to prove it is fit for purpose.
Do I still need a separate Damp Proof Membrane in the ground floor?
Our gas membranes are water resistant and airtight by the nature of their design and they can act as a replacement for the floor DPM in most situations. Depending on the floor construction, it might still be preferrable to utilise both membranes in the assembly. For example, where the gas membrane is installed below the insulation and floor slab, laying a separate a DPM above the insulation will act as a separating layer when the slab is being poured.
How do you deal with service penetrations coming through the floor?
Some penetrations through the floor assembly are unavoidable and it is a case of sealing around them as effectively as possible. We manufacture a variety of accessories to deal with these penetrations such as gas resistant Top Hats, foil-faced bitumen tapes, and liquid applied sealants. The most common penetrations and details are highlighted in our GM Details datasheet and explains the best method of ensuring they are well-sealed and gastight.
Can membrane laps be taped or welded?
Both are acceptable methods of sealing laps between membranes in most situations however extra care should be taken if welding a membrane incorporating a foil layer, such as Protech GM Super, because the heat from the weld can affect its performance and integrity. On contaminated sites where hydrocarbons or VOCs are of concern, we recommend all laps should be welded and not taped.
Latest Ground Gas Protection News and Articles
Support at every stage - from site investigation to validation
1 Site Investigation
Site Investigation Reports including Gas Monitoring Results. We can review these reports and advise routes for compliance.
2 System Design
Full Ground Gas Protection System Design available. CIRIA, NHBC & Building Regulations compliant.
Ease of specification with full NBS Plus specifications available for every product. Wide library of standard details with site specific details on request.
We are linked to Specialist Installers who are qualified to NVQ Level 2 in Gas Membrane Installation as recommended in CIRIA C735.
We have close links with independent 3rd party validation professionals, ensuring your project complies with the relevant building regulations.
Protecting Buildings On Radon Affected Land
Radon is a naturally occurring, colourless and odourless radioactive gas. It was discovered in 1900 by the German physicist Friedrich Ernst Dorn, who was studying the radioactive decay of Radium, itself only discovered by Marie Curie two years earlier. This work was expanded by the Nobel prize winning Scottish chemist Sir William Ramsey, who identified Radon as the heaviest gaseous element, 9 times heavier than air.
In ground gas terms, most radon is produced by the radioactive decay of trace amounts of uranium found in certain types of soil and rock, and as such the levels of gas present are determined by the underlying geology of the site as opposed to any historical usage or pollution.
This type of geology is most common in areas with granite bedrock such as south west England, the Peak District, north east Scotland and Northamptonshire. Aberdeen in Scotland, being known as the... Continue Reading.
Step by Step: How to Provide Ground Gas Protection
Since 2008, the number of new households in the UK has continued to exceed the number of new houses actually built. Over the last few years, the UK government has dedicated more of its resources to reversing this trend. The 2017 Autumn Budget, for example, committed £15.3 billion of new financial support to house building over the next five years, and included funds for new infrastructure, land buyouts and the creation of five new ‘garden’ towns. The government has also set a goal of constructing 300,000 new homes per year by the mid-2020s, a rate of house building not seen in the UK for nearly 50 years.
The development of greenfield sites alone is not the answer; the remediation of suitable brownfield sites must play a role in helping UK builders achieve the government’s ambitious targets for new housing provision. To this end, a number of initiatives have been launched to help streamline the brownfield remediation process. An understanding of common soil contaminants, the process of brownfield site classification, and the components that make up a comprehensive ground gas protection system is essential for new construction to be built safely over brownfield sites... Continue Reading.
Ground Gas Protection – Lessons for Developers
The Key challenges – The importance of getting it right
As the government, local authorities and developers continue to address the UK housing supply shortage, key issues around the suitability of land, as well as the safety, health and well-being of the occupants, must be a priority. Identifying sufficient suitable land almost certainly will require the safe development of housing on brownfield sites. Lessons from the past provide a vital warning for developers on the importance of getting it right the first time.
Two recent examples can help highlight the crucial role of ground gas protection and how not getting it right the consequences can huge. The first example relates to a housing development built in 2009 at Gorebridge, Midlothian in Scotland. However, the ground gas problem didn’t emerge until four years later in 2013. This resulted in dozens of families being evacuated from Newbyres Crescent after potentially deadly carbon dioxide (CO2) leaked into their homes from old mine workings in proximity to the site. As a consequence, in 2016 all 64 houses on the estate were torn down. The legal battle is still ongoing to litigate those who were responsible.
A second example covers a development built in 2014. The estate adjoins a former landfill site, which had not been used for 40 years but the risk remained of methane gas being released from underground. The developer was required to fit a layer of membrane to prevent gas from escaping into the houses, but homeowners have no evidence that this was carried out. It was subsequently clear that the development had not been completed in line with planning permission requirements and final building compliance certificates had not been issued. One homeowner who had bought a home for £130,000 in 2014, later attempted to get the home revalued as part of a remortgaging process. When the documents were returned, an estimated value of £0 was returned as a result of the problem.
Guidance and legislation – What you need to know
Key guidance for methane and CO2 ground gas protection is available for developers in the form of BS8485:2015 + A1 2019.
BS8485:2015 + A1 2019 is the ‘Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings.’
Toxic, asphyxiating and flammable and potentially explosive ground gases can enter buildings and other structures on and below the ground. They variously pose potential risks to occupants and users, and the structures themselves.
The British Standard is to be used by designers of gas protection measures and by regulators involved in the assessment of design solutions. It recognizes that there are several factors which affect the sensitivity of a development concerning the effects of ground gas and which need to be considered. It also describes a range of design solutions available for different situations. It is recommended that specialist advice is obtained in the assessment of the ground gas data and at the risk assessment phase.
BS8485:2015 + A1 2019 provides recommendations on ground gas site characterisation and the choice of solutions for the design of integral gas protective measures for new buildings to prevent the entry of carbon dioxide and methane and provide a safe internal environment. It offers a process that can be used to demonstrate that risks posed by the potential or actual presence of carbon dioxide and methane have been addressed.
Protection in practice – Lime Kilns, East Calder
An example of good practice in ground gas protection specification is highlighted at a new development of two residential properties at Lime Kilns, East Calder in Scotland.Prior to construction and in line with the guidance and legislation for brownfield site developments, an investigation of the site revealed the presence of historic VOCs, Methane and CO2. In full compliance with CIRIA C735 and the guidelines laid out in the British Standard 8485:2015 (+ A1 2019) and CIRIA C748, the chosen geomembrane, Protech VOC Flex from the A. Proctor Group was installed by the specialist gas membrane contractor Structureseal Services. As laid out in CIRIA C735 the VOC geomembrane was thermal heat welded and all joints air lance tested in accordance with ASTM D4437-08 2013 in conjunction with the third-party validation engineer. The thermal heat welded joints were carried out by approved NVQ Level 2 gas membrane installers, including the installation of the A Proctor Group’s Provoid 25 cuspated geocomposite subfloor venting blanket to form a passive dispersal layer in conjunction with Provoid ground mounted gully vents to the perimeter of the houses. This combined achieved a “very good performance” passive venting installation fully compliant with BS8485:2015 (+A1 2019) Table 6.
Martin Taylor, Commercial Director of Structureseal Services commented, “we have successfully used Protech VOC Flex on several VOC vapour protection projects. It offers high-performance protection in compliance with CIRIA C748, is extremely robust and has many benefits which make it easy to install on site. One of these being that when the geomembrane is folded the product has “memory”, which enhances the speed, finished appearance and quality of the overall installation. Protech VOC Flex is a 6-layer flexible proprietary reinforced VOC gas barrier suitable for use on brownfield sites that require protection from dangerous contaminants.”
The manufacturer’s design and specification advice allowed the project at East Calder on behalf of Concept Completed, to achieve a fully compliant design for ground gas protection measures. Developers, specifiers and contractors should consult closely with manufacturers to access technical expertise include CAD detailing and project-specific recommendations utilising the latest guidance and ensure compliance with current legislation and standards including BS8485:2015 (+ A1 2019) and CIRIA C748. This approach, complete with a full range of site investigation reports and gas monitoring results will ensure full compliance and the correct product selection.