Insulation over attic bedrooms (traditional farm house)

[aesmith]

Hi,

Ideally I'd find a contractor to do this, but so far can't find anyone interested in insulating anything except a flat conventional ceiling. So it looks like it's either DIY or continue without insulation.

Our house has traditional attic bedrooms with lathe and plaster internal walls and ceilings. The roof is sarking and slate. The bedrooms have the normal form with vertical walls of around 1m high, and sloping ceiling above that. The sloping part it fixed directly to the roof rafters. There's a small amount of flat ceiling giving a crawl space along the apex as well as along the eves on each side. Any insulation therefore needs to be pulled or pushed into the spaces between the rafters, and I assume it shouldn't completely fill the space but should leave clearance between the insulation and the sarking.

Any ideas about how best to insulate in this case? I'm still convinced there there should be a way, given how many houses of this form exist in NE Scotland.

Thanks in advance, Tony S

 

[Burnerman]

Not the nicest or easiest of jobs, this one.....rather than faff around with rockwool type loose insulation, I'd be going for the cavity slab type I think - at least it could be cut and slid between the rafters.
Wickes do a selection of stuff in their building section, and it has the appropriate fire resistance.
You are correct of course - no insulation should touch the roof underside or interfere with ventilation.
John

 

[aesmith]

Cheers. You were thinking of solid panels, cut down into sections the correct width but short enough to manhandle into the crawl space. Then post the sections one after another into the space. That might be manageable, but it's likely there will end up with some gaps between the sections, or gaps between the sides of the panel and the rafters. Would that cause an issue?

I was also wondering about some sort of roll material, that could maybe be pulled through with a draw cord.

 

[tony1851]

Doubt you'll be able to get any form of fibreglass insulation down the gap, either by pushing from above or below. It will snag on the laths and the bits of plaster sticking up, and you won't be able to ensure there's a proper air gap.

If removing the ceiling is not an option, the only proper way is to fix Kingspan under the sloping part (screw through the plaster ino the rafters) and overboard with plasterboard.

 

[aesmith]

Cheers. I'm not going to be fitting insulation on the inside if the existing plaster. That's too big a job, aside from the fact that the rooms are already small and low enough.

I guess I'll have a try at getting something through the gaps. I know what you mean about the rough surface of the laths, so was wondering about pulling some sort of polythene or similar sheet through first so that the insulation material can slide on that. I haven't measured but I think there's something like 150mm between the sarking and the plaster, so I was thinking maybe 50mm or 75mm of insulation to leave clearance outside and under the roof.

Something like Airtec or similar would be easier to pull through, but would that provide much benefit?

Tony S