The LWF Blog

Fire Safety for Facilities Management Personnel – Structural Fire Protection – Part 150

May 23, 2022 12:23 pm

Lawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 149, LWF considered how a building’s construction can help to protect against the spread of fire and smoke. In part 150, we look at why sprinkler systems were added to the Building Regulations in 2000.

Prior to 2000, there was no requirement for compartmentation in single-storey building designs in England and Wales. Approved Document B did not state any limitation of compartment sizes for such buildings and so, no compartments were required.

Some of the resulting building designs were inadequate in terms of fire protection and resulted in a number of serious fires in mainly large, single-storey retail premises, such as DIY stores and supermarkets. These buildings exhibited a very rapid fire spread followed by complete structural collapse, sometimes in less than 30 minutes.

The resultant dangers to building occupants, (including members of the public) and firefighters meant that the Fire Service lobbied for changes to the requirements. It was decided that a limitation of compartment sizes in large, unsprinklered, single-storey retail premises would be cost-effective and this was enacted in the 2000 edition of Approved Document B.

Effectively, what this meant was that if the design necessitated a large, single-storey premises without compartments, for retail purposes, then it must be equipped with sprinkler systems for fire protection purposes. This applied to buildings with a floor area of greater than 2,000 m2 unless the area was divided by compartment walls.

Scotland already had regulations in place for large, single-storey premises.

In 2007, Approved Document B introduced a limit of 20,000 m2 for the maximum compartment size of unsprinklered single-storey warehouses. The reason warehouses are subject to 10x greater compartment size than retail premises is because building occupancy is much less and members of the public do not have access to warehouses.

Compartment walls and floors need not be – and generally cannot be – imperforate. They require penetration by service ducts and risers, stairways, lifts, escalators etc. Each penetration should be enclosed in a protected shaft of fire protected and fire stopping materials, to the same fire resistance level as the remainder of the structure.

Any doors in compartment walls or floors and in the enclosing walls and floors of a protected shaft must also be fire-resisting.

In part 151 of this series, LWF will continue to look at structural fire protection and compartmentation. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.


Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.

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