What to ask your roofing supplier when choosing a roofing membrane

When selecting roofing products, choosing a supplier with an extensive range is a good starting point. This is key for sourcing high quality roofing underlays and vapour permeable membranes.

Date: 2021-09-03

Author: Klober

Category: Customer Communications

Tags: Membranes, Suppliers, Support

When selecting roofing products, choosing a supplier with an extensive range is a good starting point. This is key for sourcing high quality roofing underlays and vapour permeable membranes. With a variety of roofing membranes for UK roofers on the market, we’ve compiled a list of questions to ask your supplier up front, and ultimately offer peace of mind:

Question #1 What roof membrane best suits my specific roofing application?

It is important to consider the nature of the project so that the solution is guaranteed to address any unique challenges. For example, if the roof is forming part of an extension and is likely to push the tiles below their recommended minimum pitch, what should you consider?

Low pitch roofs are potentially problematic as they may be susceptible to water ingress because water can collect but has nowhere to drain. However, with a specialist low pitch membrane, a low pitch can be constructed without compromise.

For both low pitched and standard pitched roofing, membrane roof coverings provide the essential barrier needed to protect against water ingress. Unlike other membranes, Klober’s Permo Extreme is an ideal low pitch roof felt. The roof membrane has been designed for this purpose and caters for pitches as low as 12.5º for interlocking tiles, 15º for slates and 22.5º for plain tiles.

Question #2 What roofing components will help to future-proof a building?

Another factor to keep in mind when sourcing roofing supplies, is what options help to make a property more efficient. In line with The Future Homes Standard, new homes built from 2025 must demonstrate high levels of efficiency. Therefore, it is important that roof membranes provide benefits beyond the building and installation process.

Once installed, the membrane should help to achieve excellent performance. Choosing a membrane that can be used with other airtightness products to minimise energy loss is often recommended. To minimise air leakage, a membrane with integral tape should be considered. Self-adhesive roof membrane tape is a key way to provide exceptional water tightness and protection against winds.

Having said that, failure to use tapes compatible with the chosen roof membrane could lead to subsequent failures. Klober’s Permo Ecovent, Permo Forte and Permo Extreme are all available with self-adhesive strips to provide a guaranteed permanent seal of overlaps, and Permo Air with self-adhesive strips will be introduced to Klober’s product range later in the year. Klober’s Butylon tape could also be used to seal around any batten nail penetrations.

Question #3 What added benefits do these options have? 

When choosing a synthetic membrane for a roofing project, looking for additional strength is recommended. With a variety of options available, level of strength is a good reason to opt for one membrane over another.

The vast majority of breathable roofing felts consist of a fleece top layer, the membrane itself and a bottom fleece layer. However, some options have a reinforced grid, giving them four layers. Having an additional layer provides safety benefits and is easier to work with than thicker membranes.

Despite common assumptions, a very thick membrane alone may not be as strong as a four-layer membrane. Besides, thicker membranes can be more rigid and slightly harder to work with. With this in mind, selecting a membrane with a reinforced grid retains strength while avoiding the bulk.

Low resistance vapour permeable membranes like Permo Forte, help to provide extra grip and reassurance during installation. An added bonus is the consequential resistance and means unnecessary nail tear and potential damage from a roofer dropping a tool or putting their foot through the membrane can be avoided. This means less time is required to patch repair and recover tools.

Having said that, a strong membrane and other roofing equipment is not a replacement for primary on-site safety procedures. All guidance and regulations, such as HSE’s Health and safety in roof work, should be followed when working at height.

Question #4 What weathering credentials does the membrane have?

Extreme temperatures and weather conditions make the search for a waterproof membrane for roof projects even more important. In the past 12 months alone, the UK has reported a number of record weather highs and lows. Temperatures plummeted to -23 in February 2021, the lowest temperature for 26 years. In mid-August 2020, the country saw the longest stretch of daytime temperatures above 30°C since 1976.

With this in mind, it is critical when installing a roof membrane under tiles, that it serves as a secondary barrier. Opting for a waterproof breathable membrane is an ideal way to protect against wind driven rain and snow, while minimising condensation.

Modern buildings are developed to be as energy efficient as possible, which means new homes tend to be more air-tight. This means that new builds are potentially at a greater risk of condensation, with weather also affecting this. With people spending more time at home with the heating on, and at higher temperatures, the risk of condensation is increased. This is where a breathable roof tile underlay might be the best fit.

Permo Air, for example, is a vapour permeable and air open roofing membrane, ideal to prevent condensation in the roof space. The permeable breather membrane allows both air and water vapour through, meaning no additional ventilation is required. At the same time, a vapour control layer may be used to help prevent large volumes of water vapour entering a construction from the interior.  This can be useful during the drying out phase when air movement is limited.

It is important to check the zonal performance of the membrane itself to protect against strong winds. Under BS 5534, different regions require specific zonal performance criteria - one is the minimum and five is the maximum rating. Klober’s Permo Forte low resistance vapour membrane also comes with integral tape. This makes it certified for wind zones one-five, ideal for use nationwide.

Question #5 How do I know the roof materials I’m purchasing are of premium quality?

When selecting roof products, quality and performance guarantees should be carefully considered. Not all systems have the same levels of testing or manufacturer support. For example, Klober’s Permo Extreme is tested to 1 in 50-year storm conditions. As such, it is important to ask your supplier what testing simulations the membranes have been placed under, as well as any other official credentials they boast. 

For example, all Klober products have a 10-year guarantee against manufacturing defects as standard. Plus, they conform to the relevant Building Regulations and British Standards. By choosing products with these measures, roofers, builders and homeowners have peace of mind of high-quality roofing.

It should be remembered that approval is required to prove that any breathable roof membrane products used do not require additional forms of ventilation, although this is not always possible with all new build properties. A number of Klober’s roofing membranes such as Permo Air, Ecovent and Permo Light, are British Board of Agrément (BBA) approved membranes. However, Permo Air is also accepted by the National House Building Council for new build properties.

Alongside this, training led by the manufacturer could be beneficial. At Klober, roofers can gain valuable practical experience fitting a vapour permeable underlay or non-permeable roof membrane under tiles on training rigs. Following manufacturer training and installation processes will guarantee a high standard all round. 

For more information on Klober’s range of roofing supplies, membranes and barriers, please click HERE