Fire FAQ

01. What is the difference between non combustibility and limited combustibility?

Non-combustibility

Non-combustible materials are defined by the Building Regulations applicable to all parts of the United Kingdom and the Republic of Ireland(1) and include;

• Materials classified as Class A1 in accordance with BS EN 13501-1: 2002 Fire classification of construction products and building elements – Part 1: Classification using test data from reaction to fire tests, when tested to –(i) BS EN ISO 1182: 2002 Reaction to fire tests for building products – Non-combustibility test; and(ii) BS EN ISO 1716: 2002 Reaction to fire tests for building products – Determination of the heat of combustion.
• Materials classified as non-combustible when tested in accordance with BS 476: Part 4:1970 (1984) Non-combustibility test for materials;
• Materials which when tested in accordance with BS 476: Part 11: 1982 (1988) do not flame and do not cause a rise in temperature on either the centre (specimen) thermocouple or the furnace thermocouple;

Rockwool stone wool insulation is non-combustible; Rockwool insulation products intended for use in the UK construction industry are CE marked, subject to the applicability of this scheme.For these Rockwool products carrying the CE mark:

• All un-faced (plain) products are classified A1 in accordance with BS EN 13501-1.
• All products faced with aluminium foil or glass tissue fleeces are classified A1. 
• Rockwool may supply products with other coverings such as chipboard, plasterboard or specialist facings such as open mesh scrim.Whilst these coverings may detract from the overall fire classification of any such composite product, the Rockwool insulation itself remains non-combustible. 

(1) Approved Document B (England and Wales), Technical Handbook Section 2 (Scotland), Technical Booklet E (Northern Ireland) and Technical Guidance Document B (Ireland). 

Limited-combustibility

Limited-combustibility materials are defined by the Building Regulations applicable to England & Wales, Northern Ireland and Ireland as; 

• Materials, which can be classified as non-combustible (see Rockwool outline ‘Non-combustibility, above).
• Materials classified as Class A2-s3,d2 or higher in accordance with BS EN 13501-1: 2002 Fire classification of construction products and building elements – Part 1: Classification using test data from reaction to fire tests when tested to –(i) BS EN ISO 1182: 2002 Reaction to fire tests for building products – Non-combustibility test; or (ii) BS EN ISO 1716: 2002 Reaction to fire tests for building products – Determination of the heat of combustion, and BS EN 13823: 2002 Reaction to fire tests for building products – Building products excluding floorings exposed to the thermal attack by a single burning item. Where a classification includes ‘s3,d2’ this means that there is no limit set for smoke production and/or flaming droplets/particles. 
• Any material of density 300kg/m3 or more, which when tested to BS 476: part II, does not flame and the rise in temperature in the furnace thermocouple is not more than 20ºc.

(Scotland), Technical Booklet E (Northern Ireland) and Technical Guidance Document B (Ireland). Products classified to A2 in accordance with the standard will not contribute significantly to the fire load and fire growth, under conditions of a a fully developed fire, and are therefore classified as Limited Combustible in Approved Document B

In addition to being non-combustible, Rockwool stone wool insulation is of limited-combustibility (see Rockwool outline ‘Non-combustibility’, above).  

02. What are the Reaction to Fire classifications applicable to England and Wales?

In addition to the response given to question 1, insurance design guides and Technical Guidance Document B/ Technical Booklet E of Building Regulations refer directly to both European (BS EN 13501-1) and ‘National’ (BS 476) classifications. The European system ranks the safest products as A1 and A2, with the most combustible being classified as F. Similarly, the National system extends from non-combustible to Class 4.

03. Where does it say that a roof must be fire-resistant?

Fire resistance is required when the roof also performs the function of an escape route or floor*,as defined in Technical Guidance Document B- table A1, row 4 and Technical Booklet E table 3.1, row 4; and in the ‘protected zone’ 2.5m either side of a compartment wall, referred to in the Insurer’s FPA Design Guide**, where alternative protection such as parapet walls, fire resistant ceilings or conforming sprinkler systems have not been installed. Note that in such cases, only products and constructions tested and approved to appropriate standards, such as LPS 1181 Part 1 EXT-A Grade can be used within the ‘protected zone’.

*A roof is not regarded as an element of structure in TGDB and TBE, unless it functions as a floor. Deciding if a roof is acting as a floor is a matter of judgement and clearly the top deck of a multi storey car park and probably a roof garden would meet this definition. A Roof intended to support the weight of plant and equipment is not considered as being so critical but once again, a judgement would be required, depending on the expected loads, construction  and size of the roof . The occasional piece of air cooling plant can usually be ignored but where large, heavy items  of plant, often located in a single area, are sited on a roof, then fire resistance for the roof and its supporting structure may be necessary. 

**The insurers introduced the concept of the ‘protected zone’ to minimize the risk of fire spread, as a compartment wall can only be as effective as the adjacent elements of building construction permit. This is a similar but extended concept to the guidance offered in Section B3, par 3.2.5.10 and diagram 13 of Technical Guidance Document B and section 3 par 3.21 and diagram 3.2 of Technical Booklet E.

04. What is the Loss Prevention Certification Board (LPCB)?

The Loss Prevention Certification Board is the approvals arm of the Loss Prevention Council, an organisation formed in the late 1980’s through an alliance of the Fire Insurers and the Fire Officer’s Committee. Since March 2000, the LPCB has been owned by the Foundation of the Built Environment, now renamed BRE Global, but still retains its links with the UK insurance industry.

BRE Globalis a world leading, independent, third party certification/approvals body dedicated to approving fire, security, construction, and environmental, products and services worldwide. Its approvals are designed to help a wide range of sectors, including: construction, healthcare, insurance, offices, manufacturers, shops, schools, transport & infrastructure etc. 

Approval, or certification as it is also known, is independent third party confirmation that products and systems meet, and continue to meet, appropriate standards.

The LPCB Red Books list approved fire and security products and systems for the construction industry, including the test certificate numbers and details of the constructions tested, together with the environmental profile of the associated companies.

05. What is LPS 1181 Part 1 and why is it important?

This document stipulates the requirements & tests for built up cladding and sandwich panel systems for use as the external envelope of buildings, for compliance with the LPC Design Guide for the Fire Protection of Buildings.

Products/Systems achieving an EXT A grade have met the requirements of both reaction to fire (LPS 1181:Part 1) and resistance to fire tests eg. LPS 1208, and have therefore demonstrated their ability to withstand a fully developed fire for the specified period. Even in a fully sprinklered building, a roof system would need to achieve an EXT A grade approval of 30 minutes integrity and 15 minutes insulation to meet the minimum fire resistance requirement in the ‘Protected Zone’ either side of a compartment wall. For non-sprinklered buildings, such as retail warehouses, superstores and those for industrial use, the requirement would rise to 60 minutes integrity and insulation.

Note:Products/Systems achieving an Ext B grade have only demonstrated their ability to pass the LPS 1181:Part 1 Reaction to Test to evaluate the performance of a wall or roof panel during the fire growth period.

06. Why does it appear that there is a sudden increase in fire awareness and new legislation?

The requirements for reducing the risk from fire to those occupying, in close proximity to, or indeed fighting fires in buildings are set by the various statutory acts of legislation, as determined by Government. Guidance of ways to comply with these regulations has traditionally been provided through Building Control Regulations, specifically Technical Guidance Document B for the Republic of Ireland and Technical Booklet E for Northern Ireland, although it is accepted that there is no obligation to follow such guidance as it is not always comprehensive and other means may be acceptable to meet the Requirements.

Even though a decline in fire related deaths has been experienced in recent years, an increase in high profile building fires has also been seen during the same period, resulting in larger insurance claims, which inevitably lead to higher premiums. To help with this issue, other guidance is provided through Insurance Design Guides and BRE Guidance documents which, in addition to offering advice on life safety, is intended to address the additional aspect of property protection.

Although most fires are started through the accidental ignition of the building’s contents or malicious arson in or around the property, the severity and spread of the fire may be influenced by the nature of the building fabric itself. The increasing use of combustible products in construction has caused a significant concern within the industry and in 2002, the Building Research Establishment (now renamed BRE Global) reviewed their good practice guide entitled ‘Thermal Insulation - Avoiding Risks’. Para 2.19 of this document discussed the potential problem of fire spread in flat roofs via a melting weatherproof membrane and combustible insulation. In the following paragraph – 2.19(a) they advocate the use of non-combustible insulation, the insertion of plasterboard between a metal deck and cellular plastic insulation or seeking specific advice from a ‘fire expert’ to reduce risk.

Following building fires, companies providing insurance cover for the property have been known to successfully challenge the level of their liability on the basis that the Specifier did not heed all the advice provided on the appropriate choice of construction products. In at least one case, this liability was then transferred to the Specifier and his professional indemnity insurance. Such court cases are likely to revolve around the question of whether all measures were undertaken to remove or reduce the risk to a reasonable level.

Certain countries in the UK have now replaced their traditional fire safety certification system for buildings with legislation specifically based on identifying possible fire hazards, reducing their potential to as low as reasonably practicable and recording what management systems are in place to ensure the safety of persons in the premises if a fire does start. This approach relies on a risk assessment being performed on the building which must address such issues as the suitability of the premises for its intended use, sources of fuel (including the products used in its construction), the people at risk and the facilities / procedures for removing or reducing the fire risk. Following a fire incident or if challenged by the enforcement body, usually the local fire brigade, the adequacy of the risk assessment may be determined in a court of law.

07. Is a Metal roof deck capable of preventing fire spread?

TGDB and TBE recognises that if a fire penetrates a roof near a compartment wall, there is a risk that it will spread over the roof to the adjoining compartment. A steel deck, whether perforated or un-perforated, is not itself capable of preventing heat being transferred from a fire below the deck to the layers above it.

08. Is Rockwool insulation ‘Class O’? What does ‘Class O’ mean?

Class O is the UK and Ireland equivalent to European Class B.Any products achieving a European Classification of A1 have achieved the Class O rating.

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