Roof

What are Roof Membranes?

  • 25 May 2021

Among the most important parts of your home is the roof overhead. Without a roof that functions well, the underlying building will rapidly deteriorate, and even become uninhabitable. Roof membranes play an important role in excluding water and ensuring the rest of the structure has protection. But exactly how are they made, and what function do they serve?

What makes a roof?

The average home in the UK has a pitched roof comprising several different components. Everything is built around a skeletal frame, usually made from timber. On top of this is placed a series of interlocking tiles, which distribute rainwater down into the guttering.

Beneath this is a waterproof roof membrane for added protection – a sheet of plastic acting as a barrier between the air inside the roof and the air outside.

Roof

What is a Roof Membrane?

Roof membranes come in several different types. There are breathable membranes and non-breathable ones. The former is favourable in most settings, as there is a perception that they eliminate the need for separate ventilation elsewhere. This is not always entirely accurate, and it’s still often necessary to include additional ventilation around the ridge and eaves.

The most breathable types of membrane today are ‘air open’ and ‘vapour permeable’. These represent the cutting edge when it comes to breathability, and are a result of extensive R&D on the part of the manufacturers. They’re especially useful in complex roofs, such as those found in extensions, skylight-equipped loft conversions, and heavily partitioned apartment buildings where there are many breaks in the roof, and reduced opportunity for ventilation.

Up to date guidelines can be found in British Standard BS 5250, which deals with the control of condensation in buildings.

How does a Roof Membrane Work?

The membrane’s job is to exclude external moisture from the underlying structure. While rainwater might not be able to directly pass through the tiles and into the roof, airborne droplets can find their way through. The membrane is placed on the ‘cold’ side of the insulation, and will allow moisture to pass from the inside to the outside, and still allow air to circulate below, limiting the likelihood of damp and other moisture-related problems.

How long do they last?

If a membrane doesn’t incur direct damage, it should last for several decades with minimal maintenance. It is, after all, just a large sheet of plastic. Therefore, it’s important to ensure the right sort of membrane is chosen at the outset.

Leave a Reply

Latest news

Samuel Heath

Samuel Heath: Concealment reduces risk of door closer damage

Samuel Heath’s Powermatic controlled, concealed door closer is used extensively in flats, apartments and HMOs throughout the social housing sector.

Posted in Access Control & Door Entry Systems, Architectural Ironmongery, Articles, Building Industry News, Building Products & Structures, Doors, Health & Safety, Posts, Security and Fire Protection

Hemsec: An architect’s 20-year journey to building energy efficient homes

The excellent integral insulation in Hemsec SIPs walls, floors and roofs makes it easier to deliver high quality, modern homes, says architect Iain Macbeath. And he should know…

Posted in Articles, Building Industry News, Building Products & Structures, Building Services, Building Systems, Case Studies, Cladding, Restoration & Refurbishment, Retrofit & Renovation, Sustainability & Energy Efficiency, Walls

HMG Paints

HMG Paints announce new decorative distributor Hashtag The Paint Shop

Recently opened painting and decorating merchants, Hashtag The Paint Shop, is supplying trade professionals with HMG Paints decorative coatings.

Posted in Articles, Building Industry News, Building Products & Structures, Interiors, Paints, Paints, Coatings & Finishes

GGF

GGF progress and ambition highlighted at Members’ Day

The Glass and Glazing Federation (GGF) annual Members’ Day conference proved a great success. It featured an inspirational speech by Lord Andrew Stunell.

Posted in Articles, Building Associations & Institutes, Building Industry Events, Building Industry News, Building Products & Structures, Exhibitions and Conferences, Glass, Glazing, Publications, Research & Materials Testing, Seminars, Sustainability & Energy Efficiency, Windows