To fulfil its needed function a gas proof membrane need to have both a reduced permeability to landfill gases and sufficient strength characteristics to prevent tearing or puncturing during laying and subsequent construction activities. Secondary criteria influencing the choice of membrane are price and ease of handling.

Factors that determine the permeability and strength of the membrane are the thickness and type of material applied for its manufacture.

All pattern must be carried out with due consultation with government officers. As a result, the following may possibly not be suitable for your use.

Perhaps the most commonly recommended membrane is often a 2.0mm thick High Density Polyethylene (HDPE). However, a 1.5mm really Small Density Polyethylene (VLDPE) membrane has comparable puncture and tear resistance and even though its gas permeability is higher it’s still really low and as a result acceptable. The VLDPE membrane has the advantage of being slightly cheaper and far more effortless to handle in confined spaces and to lay over irregular shapes.

Either variety is preferable to the use of PVC which won’t possess the necessary criteria and, despite being inexpensive, should not be employed being a gas evidence membrane. Gas resistant aluminium membranes is usually used in buildings above the floor slab, but will require a screed or protection boards laid more than the top to guarantee protection.

It truly is futile to bear the additional costs of installing a gas proof membrane if this membrane is incomplete or punctured. For that reason, the membrane ought to be integral with the damp proof course which ought to also have reduced gas permeability and all companies need to ideally enter the building above the membrane.

Each effort ought to be made to design the making in order that toilets and kitchens etc are located adjacent to outside walls to ensure drains can pass directly via the walls and any manholes, rodding eyes etc might be positioned outside the making.

The drains themselves must be gas tight and the design and style must assure that any subsequent ground settlement won’t open any joints within the drain pipes or pipe connections. Where services puncturing the membrane cannot be avoided then these must be suitably sealed or puddle flanged.

Provision ought to also be made for service trenches and service ducts to be vented or sealed before the companies enter the building. The annulus within a duct ought to not act being a conduit which will permit gases to enter the creating.