Just wondering which plasterboard to use for utility ceiling - washer, dryer, sink, boiler, cylinder, manifolds. Only about 2m by 3m, but has a double steel level with the joists so needs fireboard under the steels. Thinking maybe it makes sense to just use fireboard over the whole ceiling ? Then there is fireline but also fireline MR and whether to use 15mm or 12mm. 

 

The spec sheet for fireline MR says 'You should normally avoid applying skim plaster to moisture resistant boards'. But am expecting to have the plasterer skim coat the boards. So does this rule out using MR ? Will have 6 downlights in the ceiling.

 

I have one sheet of fireline on site but it has been here indoors for about 18 months - plasterer has suggested boards dry out over time and it then sucks the moisture out when skimming making it harder to plaster. So maybe 2 new sheets of 15mm fireline and bin the old sheet ?

 

Paint the ceiling in bathroom paint ?

Edited September 1, 20251 yr by Spinny

What's in the room above?

 

For noise reasons ( washer dryer boiler) I would consider double boarding it and getting rid of the downlighters. 

 

 

Landing & bedroom above, but the ceiling has been dropped to run under the steel, so room height already down from 2.62m to 2.46m, so not at all keen to double board, but was thinking fireline is heavier and better sound barrier than standard pb anyway - and I guess 15mm 20% better than 12.5.

 

Can't see a good alternative to downlights - like a kitchen we need light in the right places. And it isn't a tucked away utility so will be open and visible a good deal.

 

Lots of room above beside the steels though so was planning to put 100mm or more rockwool above.

The feel of how high a ceiling has to do with the ratio of the floor area to the ceiling height. 

 

Our 2.4m high utility (2.6mx3.3m) feels much taller than our 2.7m bedroom (5mx4.5m) so I wouldn't worry in your case. 

 

Nothing to stop you installing slim profile surface mounted downlighters. A wire with some acoustic sealant poking through the plasterboard is much less of a fire/noise risk than one punched through. 

 

Someone did a mass Vs cost chart ages ago. Standard plasterboard came out on top for noise. 

 

I'd be really careful about noise transfer on this one. Washing machines make themselves known.