On 8 Jan, 14:44, (Andrew Gabriel) wrote:
In article ,
* * * * The Natural Philosopher writes:



Thinking more about this, if you have the space, Id be tempted to try
and mount the stoff OFF the rafters altogether - to make a 'tent' of
insulation underneath, because I am concerned that condensation above
the insulation layer may in time affect the rafters: when you take a

I did this with a lean-to construction roof (over my bathroom).
I fixed the underside of the rafters with pressure treated roofing
battens at right angles, and then fixed the Kingspan to those (or in
most cases through those into the rafters. I provided a vent in the gable
end above the Kingspan, and the roofing felt looped down enough to
provide further ventilation. The rafters showed some signs of rot which
had been repaired (before my time, probably when slates were replaced),
and I wanted to make sure they stayed very well ventilated.
My worry was not condensation, but any water ingress through the roof
which I would likely not notice one the Kingspan was in place, and
without ventilation might lead to serious rotting of the rafters.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Dear all, thanks for your replies. I am the posters other half. The
loft is actually an attic room that had a low ceiling with no
insulation behind it and a couple of plaster board dividers behind
which the tiles have always been exposed (not weight bearing walls or
anyhting just boards) we want to use the room as a bedroom and
insulate it properly, as it was too cold in winter and too hot in
summer. It has an original window in the side gable. So we have taken
the ceiling down (100 years of muck) so now we have a roof that needs
some insulation before we can plaster and redecorate so it is not
quite a conversion just a bit of updating. With that in mind. would
you give the same advice?,
thanks for your help!