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Poor design for fire protection

lyledunn


You will note downlights with apertures through the 2 layers of 12.5mm Fireline board to achieve 60min fire rating. The project is a a change of use from office building to hotel with floor height 20m. The downlight arrangement even with proprietary hoods has been rejected by Building Control and in my mind rightly so. 
Whilst an armchair observation might conclude that there should be no real concern in this particular circumstance, there is no evidence to confirm that the ceiling structure, carefully detailed by the British Gypsum to achieve the desired fire rating, has been maintained.


The lathe and plaster original ceiling below the floor being protected. 
Had it been my call, I would have installed a plenum below to accommodate the downlights or used some other lighting method that would not interfere with the performance of the fire rated ceiling as stipulated by British Gypsum.

By the way, applies across 70 bedrooms so now a project major cost simply because of poor design.

  • It seems odd to cut holes that big in the firebreak and not doubt it at the time. 'not my job to question it ' I suppose.

    It is too late probably but as an aside I have used surface mount down lighters (bit like these though I used a dimmable model) on these the spring assembly comes off leaving a flat back,  in a bedsit flat where I had a ceiling that also should not be broken. The cable came through a hole of less than half inch dia and then was then back filled with intumescent mastic and that seemed to be acceptable to the fire chaps.

    I'm not sure in the case you are showing what kind of remedials would be sensible now - I can't see putting wheels of fire rated plasterboard back being that great .. is it a ceiling out job ?

    Mike.

  • Or they probably could have overboarded the original lathe and plaster ceiling so have the fire break higher then fitted a  'normal' ceiling below ?

    Gary

  • in reply to aligarjon

    Actually not an option Gary. The fire integrity of construction elements in these taller buildings with sleeping risk  iis carefully scrutinised against solid evidence from test house data. Simply boarding over the lathe and plaster creates a composite element for which test data was not available. This is irrespective of any obvious anecdotal contention. 
    To meet BC requirements, we would have needed to create a section of flooring to include the floorboards, joists, soundproofing, lathe and plaster and the 2 sheets of Fireline then send the lot away for testing, likely no change from 30K. Even if successful, the composite element would not have been tested to determine maximum span for given imposed load.

    I guess the point of my post was to advise on the pitfalls of design and build projects where the various designers fail to properly consult. 

  • in reply to mapj1
    mapj1 said:
    is it a ceiling out job ?

    Could end up being that serious Mike!

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