Post-Grenfell, the laws and guidance surrounding fire risk have become ever more exacting in relation to the maintenance, design and specification of buildings. Could building membranes be next under the spotlight? ITP examines the potential for further regulatory change in the coming years.
Over four years on from Grenfell, the construction and property sectors are still coming to terms with its impact. The outbreak of a fire at London’s New Providence Wharf development earlier this year was another wake-up call, reminding us that there is still much to do in tackling safety in multi-storey buildings. Thousands of leaseholders are facing huge bills in getting combustible cladding replaced after the Government’s Fire Safety Bill progressed through Parliament without amendments to protect leaseholders from the cost of safety work. Far from being resolved, fire risk in buildings remains a fluid issue and the years ahead are certain to see more change as follow-up legislation unfolds.
The most significant legislative response to Grenfell was the Building (Amendment) Regulations which came into effect in December 2018, requiring stricter fire safety compliance for new, refurbished and converted residential buildings with a floor above 18 metres from the ground. Architects, developers and contractors have adjusted to those new laws with significant changes to the design and construction of their schemes.
A 2019 government publication, Advice Note on Balconies in Residential Buildings, had a wider scope, with guidance which applies to all existing residential buildings with multiple dwellings, irrespective of their height. The Advice Note states that building owners should “should assess the associated risk of external fire spread and take appropriate action to manage this risk and to ensure compliance with the principle set out in Requirement B4 of the Building Regulations.” B4 refers to external fire spread and the Advice Note also cites paragraph 12.5 of Approved Document B which sets out that “the external envelope of a building should not provide a medium for fire spread if it is likely to be a risk to health or safety.”
The new Fire Safety Bill will hold building owners responsible for managing reducing fire risk in multi-occupied residential buildings. The government states that it will “empower fire services to take enforcement action and hold building owners to account if they are not compliant.”
This series of developments reflects a clear and irreversible direction of travel towards tighter regulations and higher standards of safety. Aside from the problems facing leaseholders and the onus on building owners, the construction sector also needs to be mindful that the direction of travel could cross their path again, with potential for a further tightening of safety requirements in the design of buildings.
The arrival of the Building (Amendment) Regulations in December 2018 banned the use of combustible materials in the external walls of buildings over 18m. It stated developments must use materials that are A2-s1, d0 rated or Class A1 under the European classification system, also known as Euroclass (the European Commission introduced Euroclass in 2002 to harmonise the classification of the reaction to fire for building materials based on the standard BS EN 13501-1). Certain elements of external walls are currently exempt from this legal requirement, including door frames and doors, fire stopping materials, membranes, seals, gaskets, fixings, sealants and thermal breaks.
Of that list, building membranes stand out as an element which could merit a reassessment of its exemption under current laws. Used in roof and wall installations, building membranes are a standard feature in contemporary developments. They ensure long-term protection to the building envelope, providing layers which control condensation, moisture and vapour while improving air tightness. Specialist membranes with additional characteristics, such as high UV resistance, ventilation control and energy efficiency, are also beneficial for the building’s long-term health.
The clear distinction between a building membrane and other elements exempt from the regulations is the extent of its presence within any given building. A membrane’s large, continuous surface area has the potential to assist and accelerate the spread of fire throughout a building. That factor alone presents a strong case to advocate the use of membrane solutions that are non-combustible in line with other elements such as cladding.
Under current regulations, membranes used as part of the external wall construction are required to achieve a minimum classification of B-s3, d0 under Euroclass. While the Euroclass B rating (denoting limited combustibility) is the highest for flammable materials, Class A1 and A2 rated materials are non-combustible. Building membranes are not required to comply with those higher ratings because of the technical challenges involved in manufacturing a non-combustible membrane which is still breathable to BS5250 standard.
Speaking as a manufacturer of building membranes, ITP do not believe such challenges should preclude membranes from meeting the strictest standards. The construction industry has always evolved through innovation. Advances in design and technology have redefined what is possible in sustainability; they can achieve the same for safety with life-saving improvements to this critical area of building performance.
As pioneers in engineered protective textiles, ITP have developed Safe One, the UK’s first non-combustible breather membrane. Suitable for both wall and roof installations, Safe One (pictured below) is a woven material, engineered to be rated non-combustible according to the highest level of UK and European standards. Independently tested to EN 13501-1, Safe One is rated A2-s1,d0. Prior to the launch of this innovative multi-purpose system, the highest level of flame retardant breather materials in the UK were Class 0 (BS 476 Parts 6 & 7) or Euroclass B.
We have received an extremely positive response from architects and other specifiers within the supply chain. They share our view that the regulatory framework is likely to continue a steady march towards ever-higher safety demands. With that in mind, they see Safe One as a future-proof solution and a significant step forward in safety standards.
In addition to fire risk, it is also important to consider other properties of a membrane, relating to EN 13859-2, when designing high-rise buildings. As they are particularly exposed to driving rain, especially during the open building phase, high-rise buildings rely on the breather membrane to provide a temporary external skin protecting the rest of the construction before the external cladding is installed. Only membranes that are water resistant to the W1 classification – before and after ageing – will give this protection, whereas W2 type membranes will let water through, potentially damaging the construction. With that in mind, we recommend a W1 classification for membranes on high-rise buildings.
It took a tragedy of the scale of Grenfell to bring about an industry-wide reset of design and specification practices. Buildings are now being constructed to a much higher standard of fire safety and the UK’s regulations now set a benchmark which other countries are following. The government seems intent on raising the bar in the years ahead. So far, the focus on cladding has meant that membranes have received comparatively little scrutiny, but they could become the next key building element to feel a regulatory impact.