Keith Dunbar wrote:

Right. Sounds promising, and not too expensive - given that I would only
need to put the PIR foam boards where I want to have flooring (I'm going to
put 8' x 4' sheets of chipboard on 2" x 1" timbers between rafters for the
bulk of my storage).

With rafters being the sloping bits, I am having trouble visualising this...

Two questions.
What exactly are PIR foam boards?

Polyisocyanurate foam. Common trade names are Celotex, Ecotherm,
Kingspan etc. Its a rigid foam with foil covering on each face.

How does 50 mm PIR foam board compare with 4" glassfibre as insulation?

If you take a rough estimate as it being twice as effective for a given
thickness, then the two would be comparable.


--
Cheers,

John.

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