Christian McArdle wrote:

If a natural slate roof is unfelted, does this provide any ventilation to
the underside? I'd like to jam some celotex between the rafters, but won't
be bothered if I need to install specific ventilation at eaves and ridge.
The roof covering will probably be replaced in the next five years, when
felt and specific ventilation can be added. I just want to still have the
rafters in one piece when this happens.

The proposed layers would be:

----- --------------- ---- -- SLATES
------------ -------------
+---+ no felt +---+
| | 50 mm | |
| | air gap | |------ RAFTERS
| | | |
###| |###########| |##
###+---+###########+---+## -- 25mm celotex
##########################
########################## -- 25mm celotext x layed
************************** -- 12.5mm foil backed p/b

The loft area will be used for light storage. Several pipes, including
rising cold main pass through, so I'd prefer a warm loft situation.

Christian.



Looks pretty good to me. Yes, there is enormous ventilation in unfelted
slate rooves. In fact they are ****ing icy in winter - been there, done
that, rented flat, no central heating, no loft insulation either....I
stuck my head through the loft hatch and although there were naff all
eaves vents snow was drifting through cracks...I didn't stay more than
one winter there.

If you are concenred, drill for eaves vents as well - then when you have
tp re-slate, you can put paper underneath and not have to mess with teh
eaves.

Make sure you foil seal VERY well as well. Deven micro draughts make a
HUGE difference. I am stopping up all mine at the moment.