DIYbanter - View Single Post - Running lighting cables inside insulated roof/ceiling

dennis@home

On 06/03/2014 10:43, wrote:

which alternative? Yes, PIR is a much better performer, per given
depth. And a poorer performer per cost.

That depends on what figures you use..

The energy saving trust says that 135mm of glass wool is about the same
as 100 mm foam.

However they also claim that 75mm of foam with foil faces is about 30%
better than 110 mm of foam.

I don't trust either and I suspect the testing method makes a lot of
difference.

They don't give figures for fibreglass in those easy lay tubes with foil
on one side.