A crucial element of construction is ensuring a property is protected against dampness and mould formation. Not only is damp and mould aesthetically very unappealing, but it can also cause health problems for the occupants and the property. As of 2015, using the correct breather membrane is now considered standard practice within the British Standard for Slating and Tiling BS 5534.
Fastbuild stock a range of roofing products and materials, so you can order everything you need to fit a roof, all with next day delivery.
What Is A Breather Membrane?
A breathable membrane assists with ventilation and essentially allows a building to breathe. Breather membranes minimise the ability of dampness and mould forming in the external area of a property. They are installed in exterior walls and roof structures to prevent water from penetrating through the structure and other external issues such as insects and dirt. However, their vapour-permeable quality allows moisture to escape when it evaporates.
With the demand for high thermal efficiency increasing amongst clients, modern homes must be airtight and have an excellent ventilation plan to ensure moisture levels are managed correctly.
Condensation is a particular cause for concern in homes and properties. Installing a breather membrane will help the building breathe and allow moisture to escape rather than sit within the walls and cause damp and mould issues. Breather membranes also help insulate the property and protect it from external issues.
What Is The Difference Between Breather Membrane And Vapour Control Layer?
Vapour control layers also play a vital part in ensuring a property stays damp and mould-free by minimising condensation issues within a building. You will often hear the two products talked about as though they perform the same function; however, although the tasks they perform are similar, they are slightly different.
- A breather membrane has two functions; to allow vapour to escape from inside while preventing water ingress from outside, allowing the building to 'breathe.'
- A vapour control layer reduces the amount of warm, moist air entering a property which will, in turn, prevent condensation from collecting inside the wall.
There is also a difference in where each membrane is placed, with the breather membrane positioned on the outside side of the insulation and the VCL on the internal side of the insulation
These two products are also used in conjunction with one another. The breather membrane is a layer on the external edge of the insulating material, whereas the VCL sits on the inside of the insulation.
What Type Of Breather Membrane Should I Use?
As part of the 2015 amendments to the British Standard for Slating and Tiling, using the correct breather membrane for the specific regions of the UK is now required, and it covers new-build pitched roofs and vertical cladding. This is due to the increasingly common issue of breather membrane 'ballooning' in high-pressure winds, which dislodges tiles and slates, which are a safety hazard.
Fastbuild has an Eco-Breather membrane, a low-weight, high-performance breather membrane approved for use as a roof underlay. It has excellent water resistance and is suitable for direct installation over insulation, boarded roofs or rafters.
H2-How to Correctly Install A Breather Membrane
Further changes in the British standards of practice for tiling and slating outline the importance of correctly installing a breather membrane. The changes to the BS 5534 state:
- They should provide a continuous under-roof barrier.
- All penetrations should be suitably sealed to prevent water from entering.
- Laps should be covered by a batten and adjusted to the nearest slating or tiling batten. Laps may also be sealed using means in line with the manufacturer's instructions.
- A nominal 10mm drape should be provided between supports to allow a moisture drainage path and prevent excessive movement under wind load.
The nails for fixing battens to rafters hold the breather membrane in place should usually have a diameter of at least 3.35mm, and the nails should provide a minimum of 40mm penetration into the rafter. So a nail length of 65mm is generally recommended.
For more information regarding the vapour and water control barriers that Fastbuild stocks, don't hesitate to contact us today or visit our construction knowledge centre for more helpful blog articles.
