Discovered house has no loft insulation... Question re. how to fit though in one odd area...

Gorecki

Request for help from anyone with experience of laying modern insulation in old houses with restricted space/airflow.

Hi,

I moved house in January to a small 3 story house with a bigger old bit (single brick wall, over 100 years old, but good condition), and a small extension (2002).
The roof over both bits seems newish and in good condition (material between rafters and tiles etc), so presumably fitted in 2002.

I just checked the loft (re. heating bills) and, whilst the new small extension has 30cm loft insulation, surprisingly the bigger old bit has absolutely none (other than a small bit down one end presumably left over from the extension)...

I think fitting it over the main bedroom is straight forward, but the second bedroom is trickier and I'd appreciate any thoughts...

It has a vaulted (sounds posh, it isn't) ceiling (see drawing).
This means there's a small 1meter x 8cm gap between the ceiling edge and the material of the roof (see drawing, photo with red arrows, photo of gap)
The height of this gap is about 1 rafter/8cm

What would you do in this area?
If I don't fill with insulation, heat will escape through this gap, but I don't think there's a way of filling it with loft insulation without the insulation being in contact with the roof fabric, which I gather isn't recommended.

I'm planning on using Knauf eco-roll (mineral wool), 100mm, topped with 170mm for the rest of the house (photo of other area attached for interest)

If anyone has any expertise/knowledge on this, I'd appreciate it. If realistically it's only best practice not to bridge the ceiling to the roof with insulation in a small area, but fine, I'd rather fill it to insulate better, but obviously don't want to seriously cause damage to the roof.

Thanks a lot for any help :-)


Drawing showing side view of second bedroom with gap on the left, and top down plan of house showing second bedroom (with chair) and main bedroom at front


Photo of second bedroom roofspace, showing reminants of extension's insulation in the end and you can just see the gaps on the left I'm unsure how to approach (marked with red arrows)


Picture looking down into the small, 1 rafter high gaps between the fabric of the roof and the ceiling of the second bedroom below. Not sure how best to insulate these.


Picture of other end of the house for interest/don't think this bit is difficult to insulate

Norman_Castle

I've got similar sloping ceilings at the edges of a room. They're insulated with 25mm polystyrene sheets but I'm not sure how effective it is.

DougMLancs

I’ve seen I’ve seen these recommended before on here for insulating whilst maintaining ventilation - might work well for your situation? https://klober.co.uk/roof-ventilation/eaves-roof-ventilation/p/loft-vent-tray

FreeBear

Not much you can do to insulate that void at the edge from the loft space without compromising ventilation. The best way would be to tackle it from below. Fix some insulated plasterboard to the ceiling below, making sure the edges are beveled to match the walls/ceiling. Skim, and then redecorate.

I'd also look at insulating the solid brick wall at the same time. Yes, it will cost extra for materials, but if you are paying for a plasterer, it won't add anything to his bill.

Gorecki

Thanks everyone. Following a thread from Doug's very helpful link, I found a very similar material built exactly for this purpose.
It's essentially a plastic sheet with a corrugated pattern you slip between the roof and the mineral wool in tight places to maintain the ventilation and will use that.

Thanks :-)

BUFF

Gorecki said:

I found a very similar material built exactly for this purpose.
It's essentially a plastic sheet with a corrugated pattern you slip between the roof and the mineral wool in tight places to maintain the ventilation and will use that.

care to post a link?

Gorecki

At BUFF, Sorry I missed your post. In the end the ones I bought I wouldn't recommend (they were quite flimsy so extremely difficult to keep in shape when putting between the eaves).

Essentially if you search for "Corrugated plastic ventilation sheets roof insulation" there are loads of options.
They're basically just wavy plastic you put next to the roof tiles and put the insulation beneath, which keeps air flow from the eaves into the roof, but make sure you get stiff ones, the ones I had were a right pain to use (I oddly can't find the email/the link I originally used)