Property being refurbshed - New ceiling to include fire protection and sound insulation.

[Jasonss]

semi detached property.
one of the rooms in my property goes through the party wall, so they have a room above mine.
the ceiling is only lath/plaster under joists with their floorboards sat directly ontop of the joists. nothing else is between.

i want to upgrade the ceiling.

2 hour fire resistance is 2x layers of fireboard and skim.
i also want to put in sound insulation.

i could suspend a new timber ceiling below the existing joists however im limited on head height.
if a new timber ceiling is suspended, whats the best way to sound insulate it?
is it rockwool sound insulation type over the top of the new suspended ceiling at 90 degrees, and then rocwool slabs between the joists of new suspended ceiling, with 2x layers of firebooards, or possibly 1x layer of soundboard and 1x layer of fireboard?

maybe use kingspan type rigid insulation?

or is another setup a better idea?

thanks

 

[jeds]

Suspend a ceiling below. You don't mention the spans but you could use 50x100 joists with a number of wire intermediate supports if the spans are too great for that size. Lay 100mm acoustic mineral above the joists - it's important that there are no gaps in the mineral. Then double board the underside with 2 layers of 15mm acoustic board fixed to resilient bars. Each layer must be staggered joints and the edges thoroughly sealed with acoustic mastic sealant. 2 layers of acoustic board gives you plenty of fire protection.

If it's possible an alternative is to remove the lath and plaster ceiling and use 50x200mm joists set partly between the existing floor joists.

Forget using rigid insulation. It's not an effective acoustic material in that situation.

 

[Jasonss]

great thanks
yes the lath and plaster can come down and joists could go between.
the span is only 1800mm

if 100mm acoustic is laid above the joists, wouldnt it be better to also lay 100mm between the joists?
im not sure what resilient bars are but ill google it.

thanks

 

[Jasonss]

if fire rates spots are put in the ceiling i assume this is going to effect the sound insulation barrier quite a bit?
with the head height being a problem, and the possibility that this would be turned into a downstairs bathroom, spots is the ideal form of lighting.

 

[endecotp]

I know I keep posting this link but it really is good for soundproofing:

http://www.soundstop.co.uk/soundproofing_ceilings.php

Re lighting, surface-mounted LED downlights are available.

 

[Jasonss]

great link.
ive probably got enough height for an independent suspended ceiling.

 

[tony1851]

Why two hours' fire resistance?

 

[Jasonss]

sorry, that could be 60 mins.