How to retro insulate ground floor ceiling

OB1CAN

Hi ,

I am hoping to avail of your knowledge base yet again.

I live in an 80 year old house. I slabbed the external walls with insulated board last year but the joists between ground and 1st floor are empty of insulation. I can't lift the boards to access these now.

My worry is that the heat is just rising up and up.. Can I screw the insulated board to the existing ceiling downstairs ? The ceiling height is about 8.5 feet so there's a spare few inches / room for board.

Would i need some sort of screw mushroom fittings to secure the board up ?? Are there such things as screw mushroom fittings ?

Any advice would be greatly appreciated.

Thanks,

OB!

sky6

Is the ceiling plastered already, The reason I ask is I have seen double slab ceilings come away a a few months if slabbed using slab nails. Having said that
I'm sure some of the plasters will tell you exactly what you can do.
To answer you question. Yes you can buy Metal Mushroom Washers in most builders providers. You then choose whatever length screws you need which just go through the center of the washer.

CBYR1983

Not to deviate, but is this regulation in new builds? Most older houses I've lived in seem to have smaller rads upstairs to compensate? just wondering if this is standard now.

I don't think you'd get a great u value using a warmboards on a ceiling. What thickness are you thinking? Plus acoustic not great. Better than nothing, and I'd do it myself if I was starting from scratch but I'd also want to insulate between joists.

Messy job either way, but you know all about that from your walls. I imagine you'd need to screw to joists.

OB1CAN

Thanks sky and thanks cbyr.

to answer your question sky >>The existing ceilings are plastered..


And cbyr , yes I was thinking that I was going to screw to the joists. So I'm thinking getting some wide plastic washers and some screws about 4 to 5 inches long and drive some 76mm insulated board to the joists via the existing plaster board on the ceiling. Then get someone to give it a skim afterwards.

It's not about getting a better U value but more to create as warmer and more cosy athmosphere on the ground floor.. The exisiting rads up stairs are huge !!!

But we spend most of out time on ground level that I was hoping to make it more comfortable and also reduce the heating bills in these times of ours , that challenge us all both financially and climatically.

Any advice or input would be appreciated.

Regards,

OB1

mfceiling

You can screw insulated plasterboard over your board and into the joists.
Mushroom fixings are for drilling and hammer fixing boards to block walls - not for timber joists.
If you decide to do this don't scrimp on screws - put plenty along each joist and an extra couple where the boards meet each other.