Author Topic: Voids passing through fire resisting floors  (Read 3439 times)

Offline wainy1

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Voids passing through fire resisting floors
« on: September 12, 2014, 11:00:19 AM »
Hi all, I am seeking your expertise and views in the following matter; I am currently undertaking a FRA of a 200 + bedroom, halls of residence, the building consists of 4 floors with approximately 50 bedrooms per floor, is of a substantial construction (concrete floor and concrete encased steel columns. Each of the bedrooms contain a built in cupboard with two doors, providing access to a wardrobe in one and the other a wash basin, the doors are of a simple 3/4" plywood construction.
There is an open 9" x 9" vent (covered with large mesh) at the top of the cupboard containing the wash basin, this enters a large void approximately 2' x 2' which connects to the adjacent rooms horizontally and vertically. I believe there should be 60 minutes fire resistance between floors and 30 minutes between rooms on the same floor. It appears the existence of these voids could result in fire and other products of combustion breaching the room of origin and spreading throughout the building, the only protection from a fire in a room being the plywood door which may be or not open.
A number of FRAs have been undertaken by well-known and established companies over the past 15 years and none have identified what I perceive as a significant problem.
I welcome your views
« Last Edit: September 13, 2014, 08:47:29 AM by wainy1 »

Offline William 29

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Re: Voids passing through fire resisting floors
« Reply #1 on: September 12, 2014, 08:26:45 PM »
Can you provide any photos and perhaps a line drawing/sketch?

Offline wainy1

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Re: Voids passing through fire resisting floors
« Reply #2 on: September 13, 2014, 08:56:20 AM »
Thank you for your replies, I confirm the grills are just a simple 1/2" mesh containing no intumescent products and no fire dampers are fitted anywhere in the voids. The building was constructed in the 1950s and my initial observations/thoughts are; the voids contain all the services(water, soil pipes, etc) and are utilised as a simple passive ventilation system for the bedrooms which simply exhaust into to the roof void.I will post a picture when I return to work on Monday