Summary of Proposals: Combustible Materials Consultation update

Following a review of the ban on the use of combustible materials in and on the external walls of buildings, In December 2018 the Government introduced changes to the building regulations to ban combustible materials within relevant use high rise building over 18m.

The government promised to review the effectiveness of the ban after 1year, therefore have issued a consultation regarding proposed changes to requirements of the Building Regulations which in-effect ban the use of combustible materials in and on the external walls of certain buildings and in specified attachments to the external walls.

To summarise the proposed changes it is proposed to:

  • Change the building types covered by the ban to include hotels, hostels and boarding houses within the scope of the ban.
  • Change the height threshold of the ban to include buildings with a storey at least 11 metres above ground level.
  • Ban on the use of metal composite materials with a polyethylene core, regardless of height, purpose or use, in and on external walls and in specified attachments.
  • Extending the ban to include solar shading products, including but not limited to blinds and shutters.( this was a challenged omission at the previous amendments to Reg.7. )
  • Changing the List of Exemptions, including the temporary exemption of cavity trays in all forms of construction.
  • The extension of the exemption of waterproofing and insulation materials.

The consultation also seeks evidence-based views on additional exemptions, with materials such as laminated glass, whether there are exemptions that should be withdrawn, and clarifications on exemptions such as roofing components.

Changing the performance requirements of the ban with proposed updating the performance requirements of the ban in Regulation 6(3) and 7(2) to include reference to the updated standard BS EN 13501- 1:2018 and additional classifications A1fl, and A2fl-s1.

Commentary

On 21st December 2018 amendments were introduced to the Building Regulations 2010 and restricted the use of materials to external wall construction and specified attachments requiring that they were to achieve Class A2-s1, d0 or Class A1 in accordance with BS EN 13501-1:2007+A1:2009. – non-combustible materials being required.

This ban applies to building work, as defined in Regulation (3) of the Building Regulations 2010 including erection of new buildings and material changes of use, on buildings with a storey at least 18 metres above ground level that contain one or more dwellings, an institution, or a room for residential purposes (excluding hostels, hotels, or a boarding house).

As part of the 1 year on review views have been sought from stakeholders, including members of the public, as to whether the ban should be extended to cover additional buildings.

The government therefore had to have considered opinion as to which types of buildings should be included in a review. Buildings such as office buildings not within the scope of the ban typically have a lower risk, due to their reduced occupancy at night time, they do not have sleeping risk and are provided with different fire safety provisions, to meet the functional requirements of the Building Regulations than the ones within the scope of the ban.

Whereas other uses such as hotels and hostels are often staffed overnight, with a different approach to fire safety and include a higher level of fire detection and alarm systems in comparison to residential buildings. However, there is still a sleeping risk and residents are generally less familiar with their surroundings than in their own residences.

Building types

The consultation is asking consultees whether any other building types should be included within the amendments together with supporting evidence why. It would not be inconceivable that hospitals and care homes are suggested.

With regards to the changing the height threshold, the consultation sights recent fires in buildings below 18m and recently MHCLG issued guidance to building owners and designers in respect of the principles of B4, irrespective of whether the design technically followed the guidance, in buildings under 18m with for example, balconies and or timber cladding.

The government has returned a focus on the use of polyethylene-cored products as cladding materials, and has decided it poses such a significant fire risk that an outright ban of their use on any buildings, regardless of height or purpose, is justified.

In line with Australia, but going further, the government has defined the scope of ACM proposed in the ban, metal composite panels with a core comprised of greater than 30 percent polyethylene by mass.

It is proposed that this definition encompasses panels with outer sheets of other metals such as zinc and copper, following expert advice that these components are likely to be similarly hazardous.

Following the release of the changes to Regulation 7 a year ago, it was determined at a judicial review that solar shading products such as blinds, shutters, awnings, brise soleil, and similar products are not required to meet the performance requirements of Regulation 6(3) and 7(2). ( by a default omission from the regulation 7. scope )

However there are two aspects to consider, both equally important:

  • The importance of reducing overheating in residences and other buildings with the contribution of solar shading products to achieve overheating.
  • Solar shading, made of combustible materials, on the external walls of a building could create a path for fire spread.
  • To achieve this whilst there are non-combustible sun shading products currently these typically are non-retractable and not made from flexible materials.
  • Therefore, in line with the application of the Building (amendment) Regulations 2018 the clearest way to ensure safety is to apply the requirements of the ban on the use of combustible materials to solar shading products attached to the external walls of relevant buildings (as defined in Regulation 7(4)).
  • The government is also extending the question of possibly exempting awnings for commercial premises at ground level of mixed-use buildings.

In respect of exemptions the current ban of combustible materials includes all elements of wall construction from the outer to the inner faces as well as specified attachments.

The list of exempted components in Regulation 7(3) is intentionally narrow, with the objective of limiting as far as possible the use of combustible materials in external walls and specified attachments in order to minimise the contribution of the external wall construction to fire spread.

The current list of exempted components as per Regulation 7(3) is as follows;

a) “Cavity trays when used between two leaves of masonry;

b) Any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulations 2(6)) if that part is connected to an externalwall;

c) Door frames and doors;

d) Electrical installations;

e) Insulation and water proofing materials used below ground level;

f) Intumescent and fire stopping materials where the inclusion of materialsis necessary to meet the requirements of Part B of Schedule 1 of theBuilding Regulations;

g) Membranes;

h) Seals, gaskets, fixings, sealants and backer rods;

i) Thermal break materials where the inclusion of the material is necessaryto meet the thermal bridging requirements of Part L of Schedule 1 of theBuilding Regulations;

j) Window frames and glass.”

The government are seeking views whether there are any components that could be removed or added to the exemption list such as such as boiler flues that have a plastic inner lining, or the application of paint to preserve the integrity of the external walls whilst considering concern of risk the fire posed by multi-layered paint that does not meet the performance requirements of Regulation 6(3) and 7(2).

Cavity trays are an essential internal component of an external wall for controlling damp.

Currently, only cavity trays used in an external wall constructed of two leaves of masonry are exempted from the performance requirements.

In high-rise buildings external cavity walls are often constructed with an internal leaf that is not masonry, this has caused difficulties in construction with ad hoc trimming of materials due to the difficulty sourcing a proprietary non combustible cavity tray, thereby causing concern about the installation and longevity of the currently available alternative products.

It is therefore proposed to have a temporary 18-month relaxation for cavity trays (not achieving Class A1 or A2-s1,d0) in all forms of external wall construction in relevant buildings to give industry sufficient time to bring additional reliable compliant products to market, and for industry to adapt to their use.

Laminated Glass is made from two layers of glass with an organic vinyl interlayer and is currently exempt from Regulations 6(3) and 7(2) but only when included within a window frame.

However, for aesthetic reasons laminated glass is often used in the construction of balconies, there is currently no laminated glass available, for external use, able to achieve the appropriate classification (i.e. class A1 or A2-s1, d0) because of the interlayer, even though it is possible to have fire rated laminated glass.

To adopt toughened glass contradicts with guidance as it can cause harm to persons in proximity below the shattered glass.

Whilst balconies can be designed with other forms of guarding, It is thought the risk posed by the interlayer poses minimal risk.

Therefore this medium is part of the wider technical review of Approved Document B to gather evidence on the fire risk of glass balustrades before considering whether to exempt laminated glass in balconies.

Roof components

Membranes used as part of an external wall are exempted components listed in Regulation 7(3).

Approved Document B recommends that membranes used as part of the external wall construction achieve a B-s3, d0 classification.

Roofs pitched at an angle of less than 70 degrees to the horizontal are not included in the definition of an external wall (see Regulation 2(6)(a)(iv)).

Roofs pitched at an angle of more than 70 degrees to the horizontal are only part of the external wall where that part of the roof adjoins a space to which people have access (except where access is only for carrying out repairs and/or maintenance).

Roof parts (unless included within Regulation 2(6)(iv)) are also listed exemptions in Regulation 7(3)(b) where connected to an external wall.

However, there appears to be some uncertainty around the continuation of membranes used in a roof system when it is continued to the external wall.

The consultation seeks views whether additional clarification is required in the revised Part B

Materials Below Ground Level

Water proofing and insulation materials used in external wall construction below ground level are exempt from the requirements.

It is seeking views on amending the current exemption in Regulation 7(3)(e) for water proofing materials and insulation to include material used below and up to 250mm above ground level, which is considered would have no impact on the fire risk.

Lunchtime Training & CPD – Salus surveyors continue to be active in delivering valuable lunchtime CPD sessions nationwide. If you would like further information about any of information on this page or other Building Regulations or Fire Safety Legislation please contact Paul Meadows or email: info@salusai.co.uk

By |2020-02-18T17:35:58+00:00February 18th, 2020|General, Latest News|0 Comments