Fire FAQ's

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. 

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

(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

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 Approved Document B 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 Approved Document B - Table A1, 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 Approved Document B, 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, Diagram 30 of Approved Document B, Volume 2.

04. What is the Regulatory Reform (Fire Safety) Order (RRFSO) 2005 and why is it relevant to the designer, when we already have CDM and Approved Document B?

In simple terms, Approved Document B of the Building Regulations provides minimum life safety fire design requirements for new structures whilst the CDM Regulations require minimum safety standards during the construction phase. However the RRFSO 2005 requires adequate fire safety management of property upon occupancy and as such, must evaluate and take the necessary precautions to adequately reduce any fire risks associated with products used in the construction process. In practice therefore, each remit cannot be viewed in clear isolation but can involve considerable areas of common concern.

Both the Building and CDM Regulations require designers to provide adequate information relating to fire risks during occupancy and/or future construction works or routine maintenance. Of particular interest, however, is the potential for the RRFSO 2005 to impact upon the design phase of a new build project.

A further interpretation of the design implications contained within the RRFSO can be found in the Department for Children, Schools and Families document ‘Roof Coverings in Schools’ page 27 which states –

“…….designers are now required to communicate all aspects of the design which may affect the eventual fire risk assessment, including the use of combustible products in the construction. This underlines the new fire prevention approach, which asks designers/specifiers to identify and address potential fire risks. In order toaccomplish this effectively, specifiers must ensure that they have sufficient informationrelating to their proposed construction.The consequences of errors resulting fromjudgements based on the acceptance of misleading or inaccurate information couldlead to criminal prosecution.”

05. 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.

06. 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.

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

Guidance on ways to reduce the risk from fire in buildings has always been provided within Approved Document B, Insurance Design Guides, fire legislation and BRE guidance documents. However, with the introduction of the Regulatory Reform (Fire Safety) Order in 2005, the focus of responsibility in the event of a fire has been more clearly defined.
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.  

In 2002 The BRE reviewed their good practice guide entitled ‘Thermal Insulation Avoiding Risks’ and within this document (para. 2.19) they discuss 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 advise from a ‘fire expert’ to reduce the risk.  

Similarly Approved Document B, Volume 2, Paragraphs 8.29 and 8.30 of ADB2 states that, where a compartment wall is taken up to meet the underside of this type of roof deck construction, a zone of the roof 1500mmwide on either side of the wall should have a covering of designation AA, AB or AC on a substrate or deck of material of limited combustibility.

Fire-resistance ceiling, the insulation would be the substrate and would need to be of ‘Limited combustibility’, as defined in Approved Document B, Table A7. 

Note:It should be noted that foam/plastic insulation products do not come within the ADB2 definition of non-combustible or limited combustibility in accordance with Approved Document B.

08. Surely if I have a Fire Certificate then the building is deemed to be fit for purpose and my liability is limited?

In October 2006, when the RRFSO came into effect, Fire Certificates ceased to exist and were replaced with Fire Risk Assessments as the primary method to manage fire risk in buildings. At the same time, fundamental changes were made to the way in which the Fire Service operates that increased their powers. Without prior warning, Fire Officers are now able to enter and inspect a building, take samples and initiate prosecution of negligent parties.

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

ADB2 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.

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

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

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