Industry Comment Fire-rated ceilings:a guide

Fire rated downlights and other fire rated ceiling penetrations need to keep pace with changing ceiling designs. TENMAT believes it is the first fire protection product supplier to fully address this issue with large scale tests being undertaken for fire rated downlights, fire rated air valves and fire rated ceiling fans in lightweight, modern ceiling joist designs.

By Rupert Coggon, Product Development Director, TENMAT. I

am sure that everyone will have noticed how fire protection and the need to “do it right” is now a major focus of current

and future legislation. What you may be less aware of is that

electricians fit, and often take “full responsibility” for one of the most prolific fire protection product types used in the UK – the fitting of fire rated downlights, ceiling fans and air valves into fire rated ceilings. Building regulations are very clear in that “the

product used should be shown to have the required fire test data to reinstate the fire rating of the construction in which it is being fitted”. If the test data does not conform to the construction that the product is being fitted into then you could be fully or partly responsible for that installation and its fire safety, which could be life critical. Over the past 20 years, the design of fire rated ceilings has changed dramatically, particularly in terms of 30 minute fire rated ceiling constructions. It is now unlikely that you will find a solid timber joist system in a 30 minute ceiling and much more likely to be an I-beam or metal web joists or other light weight joist system, which perform very differently to the old solid timber joists in a fire situation, and require a much more efficient and high performance level of protection at the point where any penetration takes place.

Both I-beam and metal web light weight joists

have very little “sacrificial” material compared to a solid timber joist and therefore if fire enters the ceiling cavity then rapid collapse will occur. Premature ceiling collapse is not only a great danger for the residents of a building but is also highly dangerous for fire fighters who enter a building expecting that the ceiling will be stable for a certain period, only to find that it then collapses on them. This is a life critical concern. Metal web joists, in particular are an open joist

system which readily allow the passage of services but also allow a fire to spread very quickly if it is allowed to enter the ceiling cavity. There are very few products which have been

tested on full scale loaded metal web joist to protect the downlight, air valve or ceiling fan penetrations, especially to the latest

26 | electrical wholesalerJune 2018

Metal web joist ceiling being fitted with downlights along with correctly tested fire covers.

Lightweight ceiling joist construction which collapsed after just eight minutes of exposure to fire. Picture courtesy of Manchester Building Control.

BS EN 1365-2 which is a more onerous standard, and most products on the market claiming to be “fire rated” have been tested with solid timber joists which simply do not meet the required level of fire protection. In fact many of the products currently sold on the market do not seem to have any test data to

back them up at all. It is very easy for installers to assume that they are fitting the correct product, but if not correctly tested then they could be putting lives at risk as well as their own reputation, and potentially their business. Building control in Ireland has already taken the lead to strengthen the current requirements (which already exist across the UK) to ensure that all products are correctly fitted. Checklist:

1. Is the ceiling fire rated? 2. What is the fire rating (typically 30, 60 or 90 minutes)?

3. What is the ceiling construction (typically solid timber, I-beam or metal web joists)?

4. Check that the fire rating of the product you are using matches the fire rating and construction type. 5. DO NOT trust a simple statement that says “fire rated”; it is meaningless. If installers are at all unsure if the product they

are fitting is correctly tested for the application, they should contact the manufacturer and ask for a test report or assessment report. They may be shocked by the number of manufacturers who cannot provide this.

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