AL_n wrote:
There is a powerful draft up in my loft. I am well aware that a loft should
be ventilated, but if the wind whistles right through it's going to suck a
lot of heat out of the house in Winter. I've just added 170mm of rockrool
to the loft, but I'm wondering if it would make sense to cut down on the
breeze that's getting in. It's an old stone-built house (1850s) I can see
light getting in through some holes in the soffit at one place, and part of
the roof has no felt inside, so the wind gets in between the roof tiles
there. In the interest of thermal efficiency, should I block some of the
sources of the drafts?


Better is to cover the insulation with something windproof.

Boarding, or simply plastic sheet maybe.

Fixing holes in eaves that were always built that way is a thankless
task IMHO.
Thanks

Al