The Architects’ Journal Architecture News & Buildings
While roofing membranes may go unnoticed once a roof is complete, their importance is unquestionable. Fundamentally, they are meant to stay concealed beneath the surface as a secondary barrier against the elements. Besides protecting from the ingress of rain, snow and dust, another key function of roofing membranes is to reduce the effects of positive and negative air pressure on the roof, preventing roof damage.
Nevertheless, it is essential to remember that there is no universal solution. In an industry like construction where one size doesn’t fit all, understanding the nuances of roofing membranes can make the difference between a roof that covers and one that truly performs. So, which membrane is best for each roof?
Key considerations when specifying roofing membranes
For starters, there are three distinct types of roofing underlays. Vapour permeable (low resistance ‘LR’) membranes allow water vapour to escape from the dwelling but are airtight, helping reduce condensation risk. Yet, they can still require traditional roof space ventilation. Vapour impermeable (or high resistance ‘HR’) membranes are completely airtight and watertight; hence they require full ventilation. Think of these as a modern equivalent of the old-style bituminous Type 1F felt. Air and vapour permeable membranes allow air and vapour to pass through, which means they are fully breathable and do not require any additional ventilation.
Although it might be tempting to specify a generic underlay or one reliably used for some time, this approach does not align with responsible building practices. When choosing an underlay, it is imperative to take into account a number of key variables. These include, but are not limited to, the pitch of the roof, the ceiling detailing, the type of the roof (warm or cold), the presence of vapour control layers (VCLs) and ventilation requirements.
The structure’s location in the country and exposure should also be considered, along with the type of roof finish. Different coverings or the integration of solar panels affect the ventilation needs and, consequently, the type of underlay that should be installed.
Source:Excel Scotland- Roseisle
Covering every scenario with Don & Low’s UK-made roofing membranes
Being the UK’s only vertically integrated construction membrane manufacturer, Don & Low has developed a comprehensive roofing membrane family engineered to meet the unique demands of any roofing project across the country.
Don & Low’s Roofshield® is the market-leading air and vapour permeable roofing underlay and has earned almost 30 years of trust through continuous use and rigorous testing. Weighing 196 grams per square metre, Roofshield® stands out as the heaviest underlay in its class, providing exemplary durability and water resistance.
The RoofTX® range of vapour permeable (LR) roofing membranes is competitively priced without sacrificing quality or performance. It consists of six distinct products, each differing in weight and design, and is well-suited for fully supported or unsupported cold and warm systems.
The MultiTX® range of vapour impermeable (HR), air and liquid barrier roofing underlays are ideal for conventional ventilated pitched roof construction of cold and warm roofs. It’s durable, easy to cut and install and offers excellent temporary protection against the elements.
Why certifications matter
The performance, durability and weather resistance of accredited roofing membranes are subjected to extensive testing by independent third-party agencies and comply with industry standards. Reflecting Don & Low’s commitment to construction excellence, the company’s roofing membranes hold BBA and NSAI certifications.
Moreover, Don & Low’s roofing membranes come with Environmental Product Declarations (EPDs). By providing unbiased, standardised, and independently verified information on each membrane’s environmental impact throughout its entire lifecycle, EPDs help architects, developers and contractors effectively manage Scope 3 emissions.
Still in doubt? Call the construction experts
There is no need to stress if you’re uncertain which roofing membrane is the perfect fit for your next project. With Don & Low's team of technical experts on your side, construction excellence is always guaranteed. Call 0808 169 4444 or email membranes@donlow.co.uk for reliable, responsible advice, completely free of charge.
