Double boarding a ceiling

[Lymnol]

Hi, I'd appreciate some advice on sorting my ceiling out.

I brought the old one down some time ago as it was damaged and unsafe as a results of a leak and then subsequent building work above.

So far I've sealed up the gaps between the floorboards and installed rockwool between the joists.

I plan next to install resilient bars at right angle to the direction of the joists, partly to help with sound proofing and partly because there's an issue with uneven joists.

After that I plant to double board it, with one layer of 12.5mm firebloc board and one layer 12.5 mm Gyproc Soundbloc board. And here's where I'm a little stuck:

Do I do one layer completely first, then do the second on top of that? The first layer I plan to be the firebloc one, does it matter if it's tapered or square edge, and do I need to tape up the joints on the first layer or only the 2nd layer, and should I board them in the same pattern or a different one. I.E. Put the soundbloc 2400x1200 at a right angle to the Firebloc 2400x1200?

Any Help much appreciated.

 

[PrenticeBoyofDerry]

What is the reason for double boarding?

 

[Lymnol]

What is the reason for double boarding?

Improve the soundproofing as much as possible.

 

[PrenticeBoyofDerry]

So it's not a mixture of sound and fire proofing then?
If you are double boarding avoid having the joints of the first layer at the same place as the second layer.
Also remember to stagger joint on both layer, this will help bond the sealing and prevent cracks from movement.
Square edges boards for both are fine, if the final finish is of plaster, if the final finish is to be joint taped and filled, then tapered edged would be preferable.
One pointer I would make is, you are filling the void with thermal insulation, are any electrical power circuit in this area?
If so this could effect safe current carrying capacities of certain circuits.

 

[Lymnol]

So it's not a mixture of sound and fire proofing then?

Well, primarily, sound proofing, but I discovered about all the types of plasterboard you can get, so thought those two made a good combination. Gonna buy/rent all the tools I need to do it, just want some advice about the best way to go about it.

 

[PrenticeBoyofDerry]

So it's not a mixture of sound and fire proofing then?

Well, primarily, sound proofing, but I discovered about all the types of plasterboard you can get, so thought those two made a good combination. Gonna buy/rent all the tools I need to do it, just want some advice about the best way to go about it.

I don't think using fireboards rather than standard plasterboards, is going to offer you much more resistance to fire with the way you are planning to do things. But that's your option.