Bathroom plasterboard

[joeandrews]

I'm about to bash my bathroom ceiling down, I will re-board and get someone to skim.

I assume I just need the ordinary 12.5mm platerboard, nothing special?

I guess there will be old fashioned loft insulation in the void (it's a flat roof, 1980's), do I need any special insulation or do I get the rockwool stuff again?

Many thanks.

 

[PrenticeBoyofDerry]

I would use duplex (foil back) boards, this will create a vapour barrier with the foil.
Rock wool is as good as anything.

 

[joeandrews]

Many thanks.

How do I hold the rockwool in place as I'm screwing the boards up?

 

[PrenticeBoyofDerry]

Sorry I was not paying attention, it's a flat roof
Have you considered using a "warm roof system" This means insulating the roof externally, it's a good method if possible for flat roofs.

 

[joeandrews]

It's a large flat roof and I had it refelted last year.

Should I go Duplex boards and rockwool?

Thanks.

 

[PrenticeBoyofDerry]

If that's the case yes, but you could consider Kingspan/celotex cost more though.
To hold the wool in place, you can cut it about 50mm bigger the joist void so it stuffs in and stays, you can nail horizontal in to the just, so it sit on the nails or you could consider running lengths of string across the room at right angles to the joist as support.
Remember to leave a 50mm air gap between roof and insulation for ventilation and you will need external air vents, to create air flow.
these can be in the soffits.

 

[Richard C]

How do I hold the rockwool in place as I'm screwing the boards up?

It's not a problem if you think about it a little. If it’s a tight fit between the joists, it will more or less hold itself in place with a little help. Otherwise spray adhesive, a staple gun & some string, duct tape or even chewing gum; just be a little imaginative

 

[joeandrews]

Thanks, I'm doing it on my own so a staple gun and string it is.

Great tip.