In June 2015, BSI, the Business Standards Company, revised (and renamed) BS 8485 “Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings”.
The standard is a key piece of guidance for design consultants to give recommendation and describe methods for the investigation of ground gases like methane and carbon dioxide during development of affected sites, and regulators (environmental health officers and building control) who need to assess/approve foundation designs.
The original document; BS8485:2007 was brought up-to-date in the new version: BS8485:2015. The thinking behind this was that the original standard didn’t go far enough in regards to the specification of the gas membrane itself and the British Standards Institute wanted to enforce more stringent permeability levels, especially where methane gas is concerned. This is in order to increase resistance to methane gas permeation through the membrane.
Key changes to BS 8485:
- Clearer guidance on the interpretation of gas monitoring data and assignment of gas screening values
- Reference Technical Note RB17 characteristic situations classification using TOC (toxic organic compounds)
- Review and expanded guidance on protection measures scoring (old Table 3)
- Include reporting requirements of gas protecting measures
- Added informative guidance in annexes on radon and volatile organic compounds (VOC’s)
- More detailed guidance on interpretation of gas monitoring data
- Recommendations on membrane selection and verification
Phil Bull, Commercial Director at Visqueen Building Products said:
“It is vitally important that the industry recognises that BS8485: 2007 has gone and is no longer valid unless the contractor using the products had a planning condition in place prior to June 2015. Here at Visqueen we are adapting our existing gas barriers and membranes to ensure full compliancy required by BS8485:2015. It should be a priority for every relevant manufacturer to start the process of adhering to the latest version of the standard.” Continue reading