Fire Safety
Compliance with the minimum standards of fire safety laid down in Building Regulations is crucial in achieving buildings which provide adequate protection for life and property in the event of fire.
The content of the Regulations, the frequency and timing of revisions and the regulatory regimes differ between England and Wales, Scotland and Northern Ireland. However, in each country’s Regulations, glass performs a vital role in achieving the requirements for fire protection. Our Fire Range brochure examines the Regulations and how the requirements are met in respect of glazing.
Developments in glass have resulted in the introduction of more sophisticated products with increasingly higher fire resistance performances, in both integrity (resistance to fire penetration) and insulation (resistance to the transfer of excessive heat).
Pilkington Fire Protection Glass Range:
Pilkington Pyrostop™
A clear, laminated fully insulating fire and safety glass that offers the highest levels of fire protection (integrity and insulation), maximising the available levels of natural light and visibility. The achieved classifications for integrity and insulation (EI) are for 30, 60, 90, 120 and 180 minutes.
Depending on the thickness, it provides impact safety up to Class 1 BS EN 12600.
Pilkington Pyrodur™
A clear, laminated fire resistant and safety glass primarily designed to provide integrity but also offering full insulation (against all heat transfer) for a short period. Developed specifically for use in doors and screens, it provides impact safety to Class 1 and Class 2 of BS EN 12600 (depending on thickness). It has achieved integrity classifications (E & EW) for 30 and 60 minutes, and insulation (EI) for 15 minutes.
Pilkington Pyrodur™ Plus
Pilkington Pyrodur™ Plus is an advanced thin, clear fire-resistant laminate glass, which easily meets all the latest European fire and impact standards. Using a special clear intumescent interlayer, it offers an excellent combination of fire and impact to Class 2 of BS EN 12600. It has achieved integrity classification (E & EW) for 30 minutes, and insulation (EI) for 15 minutes.
Pilkington Pyroshield™ 2 Safety Clear
A monolithic safety wired glass for use where there is a specific requirement for both integrity fire protection and impact resistance A certificate to Class 3 of BS EN 12600 has been achieved. Available as a clear version only. It has achieved integrity classification (E) for 30 minutes.
To view further information on the Pilkington Fire-Resistant Glass Range please click here.
The relevant part of the Building Regulations is Part B – Fire Safety. There are five parts:
● B1 Means of Escape
● B2 Internal fire spread (linings)
● B3 Internal fire spread (structure)
● B4 External fire spread
● B5 Access and facilities for the fire service
Each part has a brief functional requirement, supported by the detailed guidance in the Approved Document B. There are frequent references throughout the Approved Document to British Standard BS 5588: ‘Fire precautions in the design, construction and use of buildings’. Designing to the relevant parts of this standard is often required or advised by the Approved Document.
B1 – Means of Escape
The purpose of this part is to ensure as far as possible that people are able to escape from a building or get to a place of safety should a fire start. There should be a sufficient number of escape routes which are protected from fire, and the requirements are laid down in the Approved Document, often with cross-reference to BS 5588.
In dwelling houses, windows are regarded as an escape route, but there are no specific requirements of the glass.
In the case of loft conversions, however, any glazing in the enclosure to the stair, including doors, should be fire resistant. The windows should be openable, and within 1.7m of the eaves (measured on the roof surface), to allow for escape. Where a window is installed for escape purposes, BS 5588: Part 1 ‘Code of practice for residential buildings’ recommends it should provide an unobstructed opening of not less than 500 x 850mm, and the bottom should not be less than 0.6m or more than 1.1m above the floor of the room. In buildings other than dwellings, escape routes must be protected by enclosures of adequate fire resistance. The performance requirements for the integrity and insulation fire resistance of elements, including glazing, are given in Table A1 of the Approved Document. However, if an integrity glass is to be used, there are limitations on its area as set down in Table A4.
For complex buildings, the Approved Document permits the use of BS 5588 or other codes relevant to the particular building type. The various parts of BS 5588 contain tables comparable with Table A4 of the Approved Document, setting area limits to the use of integrity glass.
B2 – Internal Fire Spread (linings)
Internal lining materials to a building can significantly contribute to fire growth as a result of flame spread across their surface, or by the amount of heat they release during combustion.
The Approved Document gives performance requirements for different situations. The main classifications are based on tests to BS 476: ‘Fire tests on buildings, materials and structures’ Part 6 ‘Method of test for fire propagation for products’ and Part 7 ‘Method for classification of the surface spread of flame of products’. All glass within the Pilkington range (with the exception of some cast-in-place (CIP) laminates) meet the highest performance specification of these tests, and so their use is not restricted by the requirements of Part B2.
B3 – Internal Fire Spread (structure)
This part of the Regulations is intended to ensure that fire is contained within the room or space of origin, and that the spread of smoke and fire is inhibited by fire resisting compartmentation, so that structural integrity is maintained for a reasonable period. The sizes of compartments are prescribed. The walls separating these compartments must achieve specific periods of fire resistance, and so the fire resistance performance of any glazing in such walls is crucial. Every compartment wall should comply with the minimum periods of fire resistance stipulated in Tables A1 and A2 of the Approved Document. The required periods of resistance depend upon the purpose group and height of the building, but the most onerous requirement is for 120 minutes fire resistance. Pilkington Pyrostop® in a steel screen has been tested to achieve 120 minutes integrity and insulation to BS 476: Part 22 ‘Methods for determination of the fire resistance of non-load bearing elements of construction’ (test reference WARRES 46730). The fire resistance performance of Pilkington products in a range of doors, door surrounds, screens and partitions can be seen in the summary table in the literature Fire-Resistant Glass Range. Doors in compartment walls should generally have a fire resistance performance as good as that required for the wall; detailed requirements are given in Table B1 of Appendix B to the Approved Document.
Any stairway passing from one compartment to another must be enclosed in a ‘protected shaft’, which has to achieve a specified fire resistance performance. Protected shafts may contain glazed screens, between the stair and a lobby or corridor, provided the screen achieves 30 minutes fire resistance in terms of integrity.
A glazed door which is needed to provide a means of escape may be inserted in a protected shaft, provided it has the same fire resistance as the shaft.
B4 – External Fire Spread
This part of the Regulations specifies that the external walls and roof of a building shall resist the spread of fire over their surfaces, and from one building to another. Diagram 36 in the Approved Document indicates the limitations on the use of combustible materials on external surfaces. As a non-combustible material, glass cladding is unaffected by these limitations. The Regulations also seek to limit the likelihood of fire breaking out of one building and reaching another. The concept of ‘unprotected areas’ is introduced for this purpose. Unprotected area is defined as any part of an external wall which has less fire resistance than the appropriate amount for the wall given in Table A2. Thus, windows containing ordinary annealed glass may well be defined as unprotected areas. The Regulations permit unprotected areas up to a maximum, depending on the type of building and its distance from the boundary. If the area of openings exceeds these areas, the openings must achieve the same fire resistance performance as the wall which contains them. Pilkington products for fire resistance enable this performance to be achieved. In roofs, the Approved Document lays out minimum distances of roof coverings from boundaries, depending on their performance to BS 476: Part 3: 1958 (External fire exposure roof tests). The Standard rates constructions according to two letters; the first indicates the time to penetration, the second is a measure of the spread of flame. Most glass products achieve AA, the best rating, and their unrestricted use in roof coverings is therefore acceptable.
B5 – Access and Facilities for the Fire Service
This part of the Approved Document defines the requirements which ensure adequate access to, and within, the building in order to fight fire. Requirements for the provision of fire fighting shafts are given. This part of the Approved Document makes no specific requirements relating to glazing, although it does refer to BS 5588: Part 5: 1991 ‘Code of practice for fire fighting stairs and lifts’, which makes reference to the use of glass in fire fighting stairs and lobbies.
To download the England and Wales building regulations Part B click here.
To download the Northern Ireland Technical Booklet E click here.
To download the Scotttish Technical Handbook #2 click here.