Light boxes above acoustical ceilings

[tmaxey]

As a Specifier, I am updating our master guide specs and have found an option in the Acoustical Ceiling spec that allows the use of acoustical ceiling panel materials to be used to make fire rated light boxes for the back of fixtures exposed above the ceiling. Is it my understanding that this should be done with drywall only or are the ceiling materials acceptable to use for site built boxes?

Thank you.

[Jerry Peck - Codeman]

[Jerry Peck - Codeman]

From everything I have found the acoustic ceiling tile is approved for that use *in that acoustic ceiling tile system ONLY*.

I also understand the reasoning for allowing it – there is no need to have the five sided box which is *more* fire-resistant than the ceiling system it is in. The membrane penetration does not require a greater fire-resistant rating than the membrane has.

Makes sense in a logical way, but then I’ve never liked the thought of using acoustic tile as a fire-resistant rated system anyway – but who am I compared to all the knowledgeable people who design, test, list and label those systems – they figure out the minimum which will work, construct the test sample perfectly, pass the test with conditions which do not always replicate real life, then give the system a thumbs up … knowing that construction is never done perfectly as required.

The key, of course, is that the installation/construction of the acoustic tile five sided box must be done in accordance with a UL Design for that fire-resistant rated system – it cannot just be slapped up there however the installer chooses to slap it together.