Pitched Ceiling Insulation

ct5amr2ig1nfhp

Hi All,

I'm looking for help and/or recommendations for insulating a pitched ceiling. The house has ~10ft ceilings upstairs and I've insulated the flat area on the attic and have it boarded for storage.
The problem is that about half the ceiling upstairs is pitched. There is only a max of about 300mm between the ceiling roof felt.

Can anyone recommend how I go about insulating the pitched ceilings in the attic? I'm guessing I have two options.

1. Fill with the roll out insulation up to about 250mm - leaving a 50mm for airflow. But how would I actually get it down the gap?

2. Use some sort of ridged insulation board. This would be easier to push down the gap.

Lifting the roof tiles is a no go.

There are downlighters as well in places. These are all LED so I'm not sure if heat will be an issue if I cover them.

To add to the complexity. There is a bay window in one of the rooms and the area above the window is pretty much unreachable. I can see some insulation is down there (100mm stuff). But I think the only way to insulate here would be internal board.

I've attached two very crude drawings.
So any thoughts or recommendations would be welcome.

Thanks, PM

huntsman77

I'd use the kingspan board ya know the one with foil either side cut it to size and push down . to make a great job out of it put the insulated plasterboard on the slope really keep in the heat

ct5amr2ig1nfhp

I was thinking of using the Knauf Flexible Slab earthwool - this stuff. If anyone has used this, can you recommend it for what I need? Thanks

Nokia08

You can always use a Superquilt insulating Blanket and tack it into place.

I'm finding it difficult visualizing the area actually!

Any chance you could provide Images of the area?

ct5amr2ig1nfhp

Yes I'll take a few pics today. If you look at Roof1 image it shows in red the highlighted areas to insulate.

When you say tack it into place... how do I actually get the insulation down the gap? I'd have to use a brush or similar and even that would be extremely difficult. The gap is only about 300mm from ceiling to roof. Essentially the bottom of the rafter is hitting the ceiling. Does that make sense?

Nokia08

Yeah I'm getting what your saying.

I assumed when you meant gap of 300mm I assumed it was between the rafters.

Instead its between ceiling and roof. All of the options your looking at including my own wouldn't be recommended. If your not willing to remove the ceilings (which I understand can be a Huge job) I would recommend beading.

If you can block off the ends of each of the "Tunnels" then that would be suggested.

Ush1

I'm not sure of the dilemma but could you not just use rigid insulation boards between the rafters in the pitched areas?

I'll be using LEDS myself through rigid boards and was told they produce such little amount of heat that it shouldn't be an issue.

Nokia08

If you just pop them in, they wouldn't be providing much insulating properties.

ct5amr2ig1nfhp

We have downlighters in some of the areas (all LED) and because of the protective covering around the downlighters, getting rigid board down past the light is going to be a problem.

My understanding is that once I have a 50 mm gap by the roof for air floor I should be ok.

Nokia08

That is correct. Attempting to achieve it is fairly difficult.

ct5amr2ig1nfhp

I've attached a picture that might help.

You'll see what I mean about the ceiling meeting the rafter. There's about a 8 inch space. And also the downlighter - there are about 8 of these in total. Some of insulation is stuffed down between some rafters. Most have no insulation at all.

Edit: The length is about 2 meters.

ct5amr2ig1nfhp

I'm going to try the flexible slab. Had a look at the stuff and it looks like that'll do what I want.

Bigcheeze

Itzel CoolS Sandpaper wrote: »

I'm going to try the flexible slab. Had a look at the stuff and it looks like that'll do what I want.

Let us know how you get on. Have similar problem.

joebre

OP,

Wondering did you get that job done yet ?
I have similar situation. Sloped ength of 2.4m.
There is 150mm of fibreglass there already.
Double rafter of 350mm so was thinking of adding another 150mm of rockwool or rigid board.
Felt that the board would be easier to slide down, rather than trying to get the rockwool under or over the fibre glass.

CBYR1983

Lots of houses in Dublin with this problem. I had this problem, just stuffed down the 100mm earthwool as best I could. Used the pole off a brush to pat it down to try to maintain air gap. In corners it was inaccessible. Plenty of air coming from there.

Not easy to do it though where there are breaks in the felt, they will block it.

Horrible job, crouching into that space, wear knee pads, gloves, mask, etc.

cerastes

why not remove the led downlighters into the room? slide a piece of rigid insulation down so its a tight fit, cut holes in the insulation for the lights from below using an elongated saw toothed stanley blade (via the ceiling hole for the light), from the attic push the wiring into the relevant hole and refit the light?
if the screws that protrude into the space could be screwed out till the points aren't sticking through they could be screwed back in once the insulation is in place (and the heads filled and touched up with some paint) or replaced with something similar diameter but longer that will help hold the insulation in place.

Just some ideas