What insulation roll would be best for this application

[drives]

Hi all,

I'm stripping out/refurbing my kitchen at the moment, and above the ceiling I have the eaves (chalet bungalow style property). The existing insulation was the old dense loft roll that I needed to take out, or at least some of it, as there was so much builders rubble/rubbish in it. Top right of the photo shows how it was arranged so presumably to keep the ceiling void slightly warmer between the ground and first floor.

I have used the glass mineral wall rolls before but I think that is too lightweight to try and position back in between the joists- plus there is a breeze that comes through the eves and it would likely blow it out of position.

Is there a type of denser insulation roll that would be best suited to this?

 

[Wayners]

Glass mineral rolls with thin wood batten jammed in to hold then foil backed plasterboard.
That's how I'd do it.
Horrible job. Wear eye and mask PPE

 

[drives]

Ok thanks. What would be benefit of foil backed plasterboard be? I was going to potentially use acoustic boards to combat a bit of noise transfer upstairs….

 

[Deluks]

Use Rockwool slabs, easier to cut and fit in place. And will help with the sound.

So you have air coming in? There is a room above this? Surely that would equal cold floor in the room?

 

[drives]

Yeah I was thinking rockwool but it just falls apart a bit when manipulated I thought? I've generally used it for partition walls where I can just cut and slot it into a flat space....

I've attached a photo of outside which hopefully helps explain. To be honest the eaves insulation arrangement has always confused me a little regarding how it is best to install, and what was done by the original builders. A lot of the services are in this space, so the loft insulation in situ has just been scattered about a bit around pipework, and wedged in between the joists at the perimeters I am guessing to try and minimise the cold air in the void between the ground and first floor.

 

[PolarNorth78]

I wanted rockwool when insulating my garage (beneath the bathroom) but couldn't get it in 150mm. I used super glass cavity batts which worked nicely as they're much more rigid. However, do wear a respirator and eye protection (full face respirator works nicely). It's a horrible job.

Decent builders merchants will have cavity batts.

 

[PolarNorth78]

 

[Deluks]

Ok, looking again. You will want a decent amount of insulation where the roof bit is.
It could be fiddly, but fixing a rigid PIR insulation board would give better thermal performance.
If cut carefully, you could fix it on top of the wall plate and up to where the floorboards begin. This will give a thermal barrier between the inside, and the roof space.
100mm would probably be ok. Foam or tape the edges, but don't make it impossible to remove in case the cables or pipes up there need to be accessed.

Once you've done that, put your slabs between the joists, then your plasterboard.
Debatable whether or not foil backed board is used. If you want the sound reduction, use a 9mm foiled board then a regular 12mn board over that.

Rockwool slabs are generally very well knitted together. If it's a new pack, not mishandled, and cut with a handsaw instead of being ripped, it holds its shape well, and if cut slightly oversized should remain between the joists until you get the PB up.

 

[drives]

Thanks all- some useful suggestions. One of those ones I guess where a number of options will work. That super glass option looks interesting.