Breather membranes on framed structures

 

What are Breather Membranes?

Breather membranes are sheet or liquid applied materials that contain many very small holes or pores. These are large enough to allow water vapour to pass but resist the passage of liquid water, without any need for ventilation to be installed directly above the insulation layer. It also averts any form of water from entering such as moisture, surface water and rainwater.

What is their function?

The function of breather membranes is to provide a barrier against water penetration from the outside while allowing migration of water vapour through the membrane from inside the building. While being typically associated with rain screens, their use is not always well understood and they are not always required.

When are they required?

A breather membrane is required unless it can be determined that:

• Any insulation in the cavity is resistant to wetting. For example, some closed cell foams and mineral fibre insulation with water repellent additives.
• No water reaches the backing wall, either directly or by migration through the insulation.

When a non-absorbent insulation is used (such as rigid foam), a breather membrane may not be required to protect the insulation. Though, one may still be used as a further line of defence against water penetration.

Where should they be positioned?

Usually, a breather membrane would be used on the outer face of insulation within the rain screen cavity to protect it from any water passing through the outer panels. For the breather membrane to successfully protect the insulation from wetting it is important that it is constant across the surface. It is essential to remember that any penetrations due to rain screen brackets should be fully sealed.

Timber frame breather membranes

Timber frame breather membranes are generally used during the construction procedure, to shield the building and the frame whilst construction happens. They can be left exposed for numerous months without any problems occurring, making them the ideal covering as the rest of the construction procedure follows. Furthermore, they help to seal the walls of the construction, reducing heat loss, as they are installed on the outer side of the insulation, which creates an additional barrier and helps to save on annual bills and energy consumption.

Buy yours with us today at www.insulationbee.co.uk or speak to one of our friendly staff on 02038839057