Cavity Barriers

[Colin Newman]

Does anyone know when cavity barriers were introduced into fire safety guidance?

I think their introduction followed the Summerland and Fairfield fires, but I can't seem to find at which point the guidance documents included cavity barriers.

 

[John Webb]

I thought fire stopping in cavities was around before Summerland since indeed that building did have some cavity fire stopping in place. Just that a number of other problems had been overlooked with disasterous consequences.

Read and Morris's book "Aspects of fire precautions in buildings", published in 1988, (ISBN 0 85125 361, BRE Ref BR 137) quotes the 1985 BR including paragraph B3(3) on fire stopping of cavities. Unfortunately the book does not make clear if this item was in previous requirements or new at that time.

[kurnal]

I have looked at the 1952 Post war building Studies books and cant find any reference there, the next port of call would be the various CP3 Chapter 4 documents that were then superceded by BS5588.
CP3 chapter 4 part 1 1963 paragraph 304 makes brief mention of voids and cavities in respect of flats where it states that where voids are created these should not pass through any wall or floor having a fire resistance of one hour or greater. But no mention of cavity barriers or maximum sizes of undivided voids.

As the Building Regs came into being in 1965 theres another starting point, though London Building Acts may also be worth a look.

[kurnal]

The first versions of BS5588 published in 1983 make reference to the provision of fire stopping and cavity barries in accordance with Building Regulations so the window at which they were introduced under Building Regs may be somewhere between 1965 and 1983.
Some progress I suppose.

It may also be worth a look at the Public Health Act and the Factories Act as well however as these bioth predate  the Building Regs.

[Tom Sutton]

Cavity barriers for horizontal voids were included in the 1972 Building Regulations which was a year before Summerland but I am fairly certain it did not include vertical voids. Also the spread of fire through ceiling voids was a problem at Hendersons but I believe it would have to be more than one incident to change building regulations.

[John Webb]

(Just to point out that Summerland opened in 1971, and being on the IoM didn't follow the UK BRs anyway but legislation from the IoM dated 1963.)

[Tom Sutton]

John the point I was making was Colin said "I think their introduction followed the Summerland and Fairfield fires"  but I believe cavity barriers was already in the E & W building Regulations in 1972. The Summerland fire was in August 1973 to me that says the fire did not introduce cavity barriers to the regs but may have revised them later.

[John Webb]

Noted - and there's little doubt that the Summerland fire did cause a lot of double checking on existing Regs and Standards outside the IoM as well as on it - there was very much a feeling of "we don't want that to happen here" about at the time, although much had to wait until the Commission's report was published in 1974.
 

[Tom Sutton]

John it was included in the 1965 Building Regulations so you can discount any major fires after that date. It may have been in one or more of the local bye laws that created the National Building Regulations for E&W the Scots beat us to it again. 

Extract from 1965 BR.

E13.- Fire-stopping

(1) Any fire stop required by the provisions of this so formed and positioned as to prevent or retard the passage of flame.

(2) Any fire stop shall

    (a) if provided around a pipe or duct or in a cavity, be made of non  combustible material or (if it is in a floor or wall constructed of   combustible material) of timber not less than l ½  inches thick, and

    (b) if provided around a pipe or duct, be so constructed as not to restrict essential thermal movement.

(3) Any fire stop formed as a seal at the junction of two or more elements of structure shall be made of non-combustible material if all such elements are required by this Part to be non-combustible.

(4) Any cavity in an element of structure which¬

   (a) is continuous throughout the whole or part of such element, and
 
   (b) has a surface of combustible material exposed within the cavity which is of a class lower than class O in regulation E14,

shall be fire stopped

   (i)   at any junction with another element of structure or with a ceiling under a roof: and
   (ii)   in such a position that there is no continuous cavity (without a fire stop) which in one plane exceeds either 25 feet in a single dimension or 250 square feet in area,

but nothing in this paragraph shall prohibit the insertion of combustible filling in a cavity.

[John Webb]

Thanks for that, Tom. With a date of 1965, did the fire in June 1960 at Henderson's store in Liverpool, where one factor in rapid spread was undivided ceiling cavities,  perhaps influence the BRs?

[Tom Sutton]

Yes possibly, but I only have anecdotal evidence about Hendersons and I think AnthonyB would have more reliable evidence about the spread, as I believe he did research on the fire.

[AnthonyB]

Yes, I have information from the coroner's inquest.

The electrical system's high voltage components (cables wrapped in tar coated paper) were the origin of the fire - it could not be exclusively established as to whether the ignition was in the cable or external to it (the former most likely).

The design & layout of the electrical installation & ventilation system was contributory to spread of fire.

The undivided voids created by false ceilings throughout the entire store contributed to rapid hidden spread of fire & smoke.

The materials of the false ceilings to these voids (& indeed other linings) were combustible & only coated with fire retardant on one side and this contributed to flashover conditions in the void in a short time.

The means of escape contributed to fire spread & hampered escape (a wooden enclosed stair, that was supposed to have been replaced 4 years ago had only temporary upgrading with fire doors and asbestolux and had it's doors hooked open - also it was not a continuous flight, you had to go to onto each floor at the bottom of a flight and re-enter through a separate door)

A poor fire procedure & lack of drills led to a delay in sounding the fire alarm. The system could only be activated from a control in the switchboard in a separate Admin building.

Despite the alarm (which ultimately failed due to power supply and cabling issues) shoppers and staff still had to be compelled to leave by the fire brigade over 10 minutes after the alarms had sounded.

11 died, 10 from the effects of smoke, one from falling from the roof. A verdict of death by misadventure was given.

Coroners recommendations:

- That legislation be put into place for inspection by the Fire Service & enforcement of adequate fire prevention, fire escapes and fire drills in large stores (introduced in the form of the fire requirements of the OSRP 1963)
- That false ceilings in stores must be constructed and supported by fire resisting material with intermediate baffles and that any services passing through to be adequately protected against fire (as introduced in Building Regs 1965)
-All staircases & escalators to be separately enclosed with fire resistant material, the exits to be directed to the street
- Automatic heat & warning detectors, water sprinklers to be installed inside & outside false ceilings
- all electrical installations should be exhaustively tested and test certificates produced before energising.

[Tom Sutton]

Does anyone know when cavity barriers were introduced into fire safety guidance?

Colin IMO there is your answer from AB, Coroners second recommendations.

[Colin Newman]

Many thanks chaps,

I've been loking into a building that has voids in excess of 60m open end to end.  The building was constructed in the 1970's and the question was asked as to whether at the time of construction there was a requirement for cavity barriers I was convinced they were, but couldn't find any references to confirm it. 

[AnthonyB]

When I reread the Hendersons Inquest for this query and also scanned over Woolworth's it's amazing how many things rang a bell with the New Look fire.

Some lessons are still not being learnt!