2.7 Spread on external walls
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Standard 2.7 Every building must be designed and constructed in such a way, having regard to the height, use and position of the building, that in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building is inhibited. |
There is a risk of fire spread on the external walls of a building. Fire could break-out through a window or door opening and spread onto the external walls. External walls close to the boundary are also at risk as they may be exposed to direct flame impingement or radiant heat flux from a fire in an adjoining building or other external source.
The use of highly combustible metal composite material panels referred to and defined in Regulation 8 of the Building (Scotland) Amendment Regulations 2022 is prohibited.
Entertainment and assembly buildings are given special consideration as a result of the Summerland fire in 1973.
Residential care buildings and hospitals also present a greater risk because the mobility, awareness and understanding of the occupants could be impaired and as a consequence, full evacuation immediately a fire is discovered may not be the most appropriate course of action.
Fire-fighters may not be able to apply a water jet from a fire-fighting hose directly onto a fire that has spread onto or within an external wall high above the ground. This is because the external wall is either inaccessible or is out with the reach capability of fire-fighting equipment. Therefore, the construction of external walls in taller buildings should not contribute to the development of fire or contribute to vertical fire spread up the facade of the building. The 11m storey height in Regulation 8, clause 2.7.1 and clause 2.7.2 is based on the reach capability of a fire and rescue service ground mounted water jet where there is sufficient pressure and flow in the water main. Designers are encouraged to seek early advice from the fire and rescue service if they wish to vary from the guidance where, for example, the façade is accessible to high reach appliances. Also, see Regulation 8 and annex 2.E for exceptions.
The guidance for fire spread on external walls of buildings should not be assessed in isolation and reference should be made to the guidance to Standard 2.1 for compartmentation, Standard 2.2 for separation, Standard 2.4 for fire spread in cavities and the guidance to Standard 2.6 for fire spread to neighbouring buildings.
The Building Standards Futures Board has been established to improve the performance, expertise, resilience and sustainability of the Scottish building standards system. A key work stream currently under development is the creation of a Compliance Plan to ensure that designs, receiving a building warrant, are constructed in accordance with the building regulations and approved drawings. External wall cladding systems and specified attachments are considered safety critical features. In the interim, documented evidence of proof of compliance should be submitted to the local authority verifier which demonstrates that the system as approved has been constructed in accordance with the building warrant.
Green walls (also called living walls) have become popular in recent years. Best practice guidance can be found in ‘Fire Performance of Green Roofs and Walls’ published by the Department of Communities and Local Government.
Conversions - in the case of conversions, as specified in regulation 4, the building as converted shall meet the requirements of this standard in so far as is reasonably practicable, and in no case be worse than before the conversion (regulation 12, schedule 6).
External wall cladding systems attached to relevant buildings having any storey at a height of 11m or more above the ground must be constructed of products which achieve European Classification A1 or A2 (see Regulation 8 and annex 2.E).
Relevant building - means a building having a storey, or creating a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 11m or more above the ground and which contains a:
- dwelling
- building used as a place of assembly, or as a place of entertainment or recreation
- hospital
- residential care building or sheltered housing complex
- shared multi-occupancy residential building.
External wall cladding systems - mean non load-bearing components attached to the buildings structure, for example, composite panels, clay or concrete tiles, slates, pre-cast concrete panels, stone panels, masonry, profiled metal sheeting including sandwich panels, rendered external thermally insulated cladding systems, glazing systems, panels, weather boarding and ventilated cladding systems. For the purposes of compliance with the building regulations and associated standards, external wall cladding systems also include spandrel panels and infill panels. Many systems incorporate support rails, fixings, thermal insulation, fire barriers and cavity barriers located behind the outer cladding.
Sheathing or backing board - attached to and providing structural support to the frame is not considered to form part of the external wall cladding system. However, where combustible sheathing or backing board is proposed in any building with a storey 11m or more above the ground, a large scale facade fire test should be carried out (see annex 2.E).
Service penetrations - service penetrations such as flues, pipes, ducts or cables are not considered to be components forming part of an external wall cladding system.
All situations – The use of highly combustible metal composite material panels referred to and defined in Regulation 8 of the Building (Scotland) Amendment Regulations 2022 is prohibited.
External wall cladding not more than 1m from a boundary - should achieve European Classification A1 or A2.
External wall cladding more than 1m from a boundary - should be constructed from products with a reaction to fire in accordance with the following table:
Table 2.9. Reaction to fire of external wall cladding more than 1m from boundary
| Building Use | Topmost storey height above ground [1] | European Classification [2] |
|---|---|---|
| Entertainment building, assembly building, hospital, residential care building, shared multi-occupancy residential building | 11m or more | A1 or A2 |
| Entertainment and Assembly Building with a total storey area more than 500 m2 | Less than 11m | A1 or A2 [3] |
| Entertainment and Assembly Building with a total storey area not more than 500 m2 | Less than 11m | B, C, D or E |
| Hospital and residential care building with a total storey area more than 200 m2 | Less than 11m | A1 or A2 [3] |
| Hospital and residential care building with a total storey area not more than 200 m2 | Less than 11m | B, C, D or E |
| Any other building | 11m or more | A1 or A2 [3] |
| Less than 11m | B, C, D or E |
Additional information:
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Includes single-storey buildings
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See exemptions in annex 2.E
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Alternative approach as described in annex 2.E may be used
There is a risk of vertical fire spread from specified attachments to an external wall including balconies, solar panels and solar shading. Fire-fighters may not be able to apply a water jet from a fire-fighting hose directly onto a fire that has spread onto specified attachments high above the ground.
Where a relevant building has a storey at a height of 11m or more above the ground, specified attachments must be constructed of products achieving European Classification A1 or A2.
Where a building (other than a relevant building) has a storey at a height of 11m or more above the ground, specified attachments should also be constructed of products achieving European Classification A1 or A2.
Extendable and retractable solar shading products such as awnings and canopies are not considered to be fixed solar shading attachments within the context of Regulation 8.
However, awnings and canopies should still be considered on a risk based approach to assess the potential for vertical fire spread in accordance with Standard 2.7. For example, multiple canopies vertically aligned on every storey of building having a storey at a height of 11m or more above the ground possess a much greater risk of vertical fire spread compared with an awning or canopy located on the ground or basement storey only.
Signage is not considered to form part of an external wall cladding system or specified attachment.