New ceiling what insulation to use

[wood1e2]

hi

I had to pull down part of out kitchen ceiling due to water damage, I have fixed the water leak issue, and ready to put up new ceiling.

In the void/between the joist was earthwool insulation, just rammed in there no matter what pipes or electricty cables there are, would repeating this be a problem?

And if it is not a problem could i use a Rockwall slab? As i hate the floppy insulation.

What I want to do is get the best insulation with the best noise reduction, as kitchen is immediately below the bathroom. At the same time I don't want to burn the house down with insullation rammed in aganist electricity cables

I've a attached a couple of pictures,

 

[Wayners]

Rock wool insulation and foil backed plasterboard as its a kitchen.
Wear eye goggles and gloves.
Horrible job to do from below.

As for sound blocking nothing will improve it. Adding insulation of any type won't do anything unfortunately.
You would need resilient bars ect to block sound.
People think I'll try and muffle sound or lower it a bit, but that won't work. It's all or nothing

 

[JohnD]

What is above it? A flat roof? A loft? A heated room?

The one thing I would absolutely avoid is old-style yellow glass fibre, which sheds irritant dust and fibres. Clean and hoover it out wearing a mask and goggles. Modern mineral wool treated with Ecose (it will be branded on the wrapper) does not shed irritant fibres and is very preferable.

As for electrical cables, they must not be buried in insulation, but on at least one side they must be exposed to the air or fastened to an uninsulated surface such as a wall or roof so that heat can escape.

The only exception is lighting circuits, because the load (especially with modern LED energy-saving lamps) is so low.

It is possible to calculate loadings for cables buried in insulation, but not worth the trouble.

Edit
I see the bathroom is above.

No need for heat insulation as it is a heated room.

And avoid fibrous insulation as it will hold water when there is a leak or overflow.

For noise, use a double layer of plasterboard, plus plaster skim, and take great care to seal all holes and gaps around joints, pipes and cables. Do not make great holes in it for downlighters. You can use pink fire foam round the edges. Foil backed plasterboard has some resistance to steam and damp.

 

[foxhole]

I found slab insulation very good at sound insulation , used it in an office between two meeting rooms so one meeting could not be heard from the other .

 

[foxhole]

What is above it? A flat roof? A loft? A heated room?

The one thing I would absolutely avoid is old-style yellow glass fibre, which sheds irritant dust and fibres. Clean and hoover it out wearing a mask and goggles. Modern mineral wool treated with Ecose (it will be branded on the wrapper) does not shed irritant fibres and is very preferable.

As for electrical cables, they must not be buried in insulation, but on at least one side they must be exposed to the air or fastened to an uninsulated surface such as a wall or roof so that heat can escape.

The only exception is lighting circuits, because the load (especially with modern LED energy-saving lamps) is so low.

It is possible to calculate loadings for cables buried in insulation, but not worth the trouble.

Edit
I see the bathroom is above.

No need for heat insulation as it is a heated room.

And avoid fibrous insulation as it will hold water when there is a leak or overflow.

For noise, use a double layer of plasterboard, plus plaster skim, and take great care to seal all holes and gaps around joints, pipes and cables. Do not make great holes in it for downlighters. You can use pink fire foam round the edges. Foil backed plasterboard has some resistance to steam and damp.

Op mentions below bathroom ( and water damaged).

 

[aveatry]

I did my kitchen ceiling last year same as you with bathroom above and I used 75mm rockwool slabs cut to a snug fit and they stay in place while you board it but I did have to pop in a few long screws here and there where the slabs were not so snug. Those rough cut joists hold them in place pretty well. I cut the slabs with an old electric knife - works a treat.

 

[Koolpc]

I once insulated the room above by installing 6ft thick insulation in the ceiling!! It worked extremely well except we had to crawl about in the room afterwards!

 

[aveatry]

I once insulated the room above by installing 6ft thick insulation in the ceiling!! It worked extremely well except we had to crawl about in the room afterwards!

its getting like that with attic insulation in the joists, wont be long before we are fitting solid roofs

 

[wood1e2]

Rock wool insulation and foil backed plasterboard as its a kitchen.
Wear eye goggles and gloves.
Horrible job to do from below.

As for sound blocking nothing will improve it. Adding insulation of any type won't do anything unfortunately.
You would need resilient bars ect to block sound.
People think I'll try and muffle sound or lower it a bit, but that won't work. It's all or nothing

Oh ok, will get the hrorrible stuff... just wasn't sure if solid insulation could be used as an easier/less hieious alternative

 

[wood1e2]

I did my kitchen ceiling last year same as you with bathroom above and I used 75mm rockwool slabs cut to a snug fit and they stay in place while you board it but I did have to pop in a few long screws here and there where the slabs were not so snug. Those rough cut joists hold them in place pretty well. I cut the slabs with an old electric knife - works a treat.

so it is ok to wedge the rockwool slabs tight as you like against pipes and electricty cables? Whilst curing the water issue, i don't want to create a fire hazard further down the line?

The joist are 150mm so I presume I could use 100mm rockwall slabs? So much cleaner and easier than the fleece/floppy insulaton

 

[aveatry]

so it is ok to wedge the rockwool slabs tight as you like against pipes and electricty cables? Whilst curing the water issue, i don't want to create a fire hazard further down the line?

The joist are 150mm so I presume I could use 100mm rockwall slabs? So much cleaner and easier than the fleece/floppy insulaton

I am not an electrician but I think someone has mentioned its ok for lighting circuits and that is all I had up there and that was only for x2 18w led lights. as for the pipes I took the opportunity of adding insulation to the radiator pipes from underneath whilst I could to save them heating the joist space.
I used foil backed board and 75mm slabs here is my thread about it all on here.
https://www.diynot.com/diy/threads/which-is-stiffer-rockwool-or-dritherm.618715/

 

[aveatry]

Something else I did whilst I could is seal all the floorboard joins from under neath under the shower tray in an effort to keep any leaks in the bathroom - the edges of which are also sealed above and below.

 

[wood1e2]

I am not an electrician but I think someone has mentioned its ok for lighting circuits and that is all I had up there and that was only for x2 18w led lights. as for the pipes I took the opportunity of adding insulation to the radiator pipes from underneath whilst I could to save them heating the joist space.
I used foil backed board and 75mm slabs here is my thread about it all on here.
https://www.diynot.com/diy/threads/which-is-stiffer-rockwool-or-dritherm.618715/

the main pipe is a gas pipe, so I presume that is just 'inert' as such.

its all the lighting cables! I completely forgot about the actual light housings, plastic block the cables go into !!!

It had the floppy horrible stuf up there previously and no fires

Thanks for the link, I wil find an electrican to ask.