Insulating between plasterboard ceiling and floorboards

[Stephen]

Hello,

Due to a leak upstairs, the plasterboard ceiling below got all soggy and I have pulled it down. Before I replace the plasterboard, is it worth putting anything above it? I've never had a house with insulation between the ground and upper floors but perhaps practice has changed since these houses were built?

I see Wickes sell slabs of insulation 2 inches thick. Does it help keep sound or noise out? Is it worth doing?

Which thickness of plasterboard should I use? I thought 9.5mm might be easier to lift but the old stuff seems to have been 12.5mm.

Thanks and Happy New Year! Stephen.

[dom]

See Part E of the Building Regulations:

[Phil L]

It can help noise reduction, but it's not required, unless the upstairs part is a toilet....to avoid listening to people laying logs while you carve the Sunday roast

you can use whichever you like, 12.5 has slightly more fire resistance than

9.5, but is heavier

[Doctor Drivel]

Yes.

Yes. It is foolish not to at this stage. The benefits are great. Cut the slabs so they jam against the joists sides. Sounds runs through the gaps. Where they meet have a slab over the join. Make sure it is jammed against the wall sides.

The thicker the better.

[Stephen]

Thanks. Thanks too for the link to the pdf, which I haven't read yet, so sorry if that contains the answers to these questions:

How much insulation do I put in? Do I just put in a depth of 2 inches (one slab) or do I fill the whole height of the joist?

If filling the complete joist height, is there a problem with the 2.5 T&E used for the ring main or is it still within limits?

Finally, how easy is it to use 2.4m plasterboard on a ceiling? I would think it would be quite heavy and clumsy to handle and there's a risk of it snapping? Is it best to keep that for use on walls and use smaller pieces on the ceiling?

Thanks.

[Doctor Drivel]

75% max of depth of space.

Two or three men can do large boards. Small for one man job. Look at Fermacell.

don't need an expensive plasterer for this as it is pre-finished. Like MDF. Great for sound supreression. Can be screwed on. A bit heavy though.

[Stephen]

Thanks.

[Stephen]

I've noticed my joists are spaced at 45cm rather than 60cm. Looking at the Wickes web site, they sell a "cavity wall insulation" that is 45cm wide.

's also half the price of their "general purpose" 60cm slabs, yet it is thicker (75mm vs. 50mm)

it be just as good, or is it worse (hence the lower price?).

Thanks, Stephen.

[Tony Bryer]

The cavity wall slabs are usually a bit denser, and hence not quite as good insulation as the quilt.

[Stephen]

So: more dense = less air trapped between layers = less insulation?

That's interesting. I think there's a third product on the web site that says dense insulation. I thought that meant it was an even better insulator but it would seem the opposite is true?

The cavity insulation is 75mm compared to 50mm of the general purpose slab, so perhaps the total effect is the same? I'm thinking it would save money (in the short term, long term ...?) and save cutting to use the cavity one!

Thanks.

[sm_jamieson]

What sort of insulation - laying logs or burning them ? Sound insulation better if more dense (up to a point !) Heat insulation better if more trapped air (less dense) Simon.

[kl_blue_forever]

Use a plasterboard lifter see:

2400 x 1200 boards 12.5mm fireboards (downstairs ceiling for protection)

Cheers

[Doctor Drivel]

>>> Would it be just as good, or is it worse (hence the lower price?). >>

Bur better in sound suppression.

[<me9]

Better for sound insulation. Possibly needed for stud walls to meet latest BRs.