Breathable Roof Membrane Installation

Where a roof includes valleys ensure the breather membrane is extended by a minimum of 300mm on each side measured from the centre of the valley.

Breathable roof membrane installation.

Our breathable range means that you only have to install one layer whereas traditional types of insulation would need installation of both a breathable membrane and then insulation. Eaves support tray firstly it is important to have an eaves support tray or a uv resistant membrane that is fitted along the eaves with the bottom edge extending into the gutter. Moisture often passes into the roof space as vapour and then condenses when it reaches a cool surface. Breather membranes have a lower total resistance to non breathable roof membranes as water vapour cannot travel through the material.

Why breather membranes are required. Breathable membranes are water resistant as well as resistant to snow and dust but air permeable. Breather membranes otherwise known as breathable membranes are used within external wall and roof constructions in order to prevent damp in buildings. Breathable roof membranes are generally installed on the cold side of insulation in the roof structure ie the side closest to the external area.

If the rafters do not meet this depth then battens should be applied to increase the depth and meet the required thickness. Installing a roof breather membrane is a relatively straight forward process but some steps must be adhered to in order to create a surface that is breathable and secure. Breathable membranes or breather membranes have been designed to improve ventilation and reduce condensation build up within the roof space as well as ensuring insulation remains effective. Bs5250 clause 8 4 1 1 3 recognises two types of underlay with breather membranes being defined as type lr breathable underlay has a water vapour resistance of less than or equal to 0 25mns g.

The following pages detail the ones that we work with regularly and are now tried and proven. At abutments turn the underlay up by at least 100mm. You would usually use them within external wall and roof structures in which the exterior cladding may not be completely water tight or moisture resistant such as in tiled roofs or framed wall constructions. Breathable roofing felt also known as breathable roof membranes can be used within both walls and roof structures particularly when the external roof or wall materials are not completely watertight.

As breathable roof membrane allows much more moisture to transfer into the batten space above it is vital that there is sufficient air movement for any built up condensation to escape. As well as this the range also comes with a built in 100mm overlap on the breathable membrane which means you won t have any excess at joints. What is a breathable membrane. They are all essentially similar they are natural non chemical green carbon friendly and breathable.

The membrane is located on the cold side of the insulation.