I’m assuming that membranes sold as DPM are not manufactured to the same exacting standards as one sold as a gas membrane? A few holes in a DPM are not going to cause too much of an issue.

 

A supermarket would reasonably be thought of as a Class D building and with a CS2 needs to score 1.5 gas points – a good slab will score 1 to 1.5 gas points; a passive venting layer under the slab scores 0.5 to 1.5 gas points and a rubbish DPM that is good enough to stop the floor being damp might be given a score of 0.5 to 1 rather than the 2 a proper membrane is accorded.

 

Does the developer need a gas membrane to comply with BS8485?

Cheers

 

 

Dear All

 

I remember on a ground gas training course (I think it was run by PAG at the Vermont Hotel in Newcastle upon Tyne) but there was definitely a gentleman there speaking who did design membranes.  He advised that recycled membranes were of no use as a gas protection membrane as they act like sieves (I may be paraphrasing slightly).  Can anyone point me in the right direction please as I need literature to back theses comments up.

 

The reason being and please keep in mind I am not discharging this condition.

 

We have a commercial development (supermarket) that has been identified as characteristic site 2.  The developer has started building without the conditions being discharged and has installed the Visqueen Eco membrane.

The Data Sheet for Visqueen Ecomembrane,  shows that this is a Damp Proof Membrane not a gas protection membrane. I have reviewed the Data Sheet that has been submitted to discharge the condition; it states:

 

IMPORTANT

 

Based on BBA, BRE and CIRIA guidelines, Visqueen Building Products recommend the use of special gas protection membranes (rather than traditional polythene DPMs) as suitable protection

against ground gases. On brownfield sites or where there is ground contamination please seek further advice from Visqueen Building Products .

 

I have advised that at this stage it would to their benefit to obtain the additional advice as indicated by Visqueen within the data sheet prior to any further discussions.

 

 

Kindest Regards

 

Lisa

 

Mrs. Lisa Maxwell
Contaminated Land Officer

Quadrant, The Silverlink North, Cobalt Business Park, North Tyneside, NE27 0BY

Tel: 0191 643 6642
Email: [log in to unmask]

 

 

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