"Tim Mitchell" wrote in message
...
This is a sort of DIY question since my business is moving to new offices
and we are doing some modifications ourselves.

We are building some more offices on a mezzanine floor above some existing
offices. The mezzanine floor is wooden joists with chipboard flooring.
Beneath the joists is a suspended ceiling with 600x600 tiles.

The BCO wants 30 minute fire protection for this mezzanine floor. This I
agree with. Our suspended ceiling contractor says that the existing
ceiling tiles provide 30 minutes fire protection, provided that any
recessed light fittings are properly hooded. He has given me the
manufacturer's specs for the ceiling tiles showing this. The BCO says that
it does not provide the protection and we need to plasterboard the
underside of the joists to provide the fire protection.

I don't want to antagonise the BCO by arguing that he's wrong, but I don't
want to do a lot of extra work if it's already suitable. Advice from the
panel please.

The fire resistance of the panels is not the only factor. In a fire, a
strong updraught can develop, which would lift the tiles and allow the fire
past them. We did get a suspended ceiling approved some years ago, but the
grid had to be steel and we had to fit special clips to hold the tiles down.

Colin Bignell