Plasterboard underlay?

[glock339]

I've been Googling this question all day but seem to get conflicting info.

Would it be OK to put a layer of 12.5mm PB on top of an old wooden T&G floor and then screw a new T&G floor on the top.

This would cover the badly damaged (but now leveled) old T&G floor, cheaply raise the floor to the level I need it to be to match the rest of the house & give me a bit of sound insulation as it will have some large speakers in there. I have read that converted flats often use PB on their floors for sound & fire proofing, but are usually sandwiched between PLY and I'm unsure if it would be OK just sandwiched between 2 layers of T&G?

12mm PLY is obviously the other option but I'll have to wait a while until I can afford a load of PLY, whereas I already have a load of PB.

Cheers!

 

[glock339]

Anyone?

Cheers.

 

[freddiemercurystwin]

The theory is sound, plasterboard can be used as the jam in a sandwich in this way so long as your floor joists are not undersized as you're adding some extra weight. The plasterboard will be fine structurally.

When it is used in floors ie separating floors between dwellings the sandwich floats on a resilient (soft rubbery) layer and helps reduce the sound transmittance but I'm guessing you're planning on screwing the lot down nice and tight so I wouldn't go expecting any magic results in the sound insulation department.

 

[glock339]

Thanks for that

I'm mainly after a cost effective way to add about 12mm height to my floor and something that will stop the drafts whistling up between the old & new T&G floorboards. I was thinking of just silicone & taping the PB joints or something??? There was an issue with the joists being thin when I bought the house so I have since over re-enforced the lot for good measure so weight shouldn't be a problem.

It's actually on my ground floor so I'm not to fussed about foot fall noise. Thought it may help reduce a little bit speaker noise from the home cinema traveling through under the suspended floor and across to the party wall on the opposite end of the house. The room has a sound proofed stud wall, then the passage and then another double soundblock boarded with rockwool wall before the party wall, but I'm thinking the floor could be the main weak point sound wise.

Cheers