Gas membrane installation in Wolverhampton

An industrial inheritance

Bilston, Ettingshall, Monmore Green and the land along the canals carried collieries, ironworks, foundries and the Bilston steelworks. Mine workings, ash, slag and demolition rubble are common finds when the ground is opened up. So are old canal arms and basins filled with whatever was to hand.

Those conditions can produce methane and carbon dioxide from the Coal Measures and from organic fill, and hydrocarbons where fuel and oils were handled. Regeneration across the east of the city, from housing on former works to new industrial units, regularly ends up with a protection level under BS 8485.

Our part of the job

The consultant investigates the ground and sets the protection level. We install to it. Before we start we check the blinding or slab is fit to receive a membrane, with no sharp edges or loose aggregate that could puncture it, and we say so if it needs more work.

Joints are welded or sealed, whichever the product's specification requires. Each pile, service duct, column and drainage connection gets its own collar and seal, because the open sheet rarely fails and the details often do.

• Installation to the specified protection level
• Laps welded or sealed to the manufacturer's method
• Every penetration collared and sealed individually
• Integrity testing and third-party validation available
• Records assembled for the warranty provider

Piled slabs and big sheds

Brownfield sites here are often piled, and a large unit can have hundreds of pile caps to detail. We plan the sequence with the frame and services contractors so each detail is done once and done properly, rather than patched after a trade has been through.

On larger and more complex slabs we recommend independent validation. An outside inspector examines and tests what we have laid and certifies it, giving the warranty provider and building control the evidence they ask for.

Housing on former works land

Not every job is a shed. Terraces and flats on old works sites in Bilston and Wednesfield bring many small slabs, each with its own drainage runs, soil pipes and meter entries. Repetition is where standards slip, so each plot gets the same checks and its own record, and the warranty file can be read plot by plot.

Drainage and gas on one site

Many of the same sites need an attenuation tank because infiltration is ruled out on the Coal Measures. We install both, with separate records for each. Where both are on the programme, we agree the order with the groundworker so the tank is in and backfilled before slab works begin.