On 13 Aug, 12:11, " wrote:
Had the modern breathable membrane stuff put in when we had our slate
roofs redone a few years back on the basis that the normal sarking
rots eventually and doesn't withstand exposure at all well. ie you
loose a slate and the sarking fails where day light (and water) can
get in between the slates... Along the gutter line our roofers put
18" (maybe 2') wide DPM with the membrane stopping 6" or so short of
the slate edge on top of it. DPM doesn't degrade...

Had my roof reslated 2 years ago, with hand-finished Spanish slate -
very happy with it all round.

Similarly had Tyvek throughout the whole roof, with additional
waterproof felt/DPM on the lowest 18-24" and lapped into the gutters.

Tyvek seems to be one product mentioned, but its non breathable?

Inside the roof it is dry, there is occasional condensation but it
does dry out no vents as such but it's still pretty drafty up
there...

As long as it stays draughty guess is good, rot needs still air in
general.at least dreaded dry rot does to get started,.

The lofts is much brighter as well, membrane is a light
colour rather than
dark.

My roofspace is bone dry, all year round, no condensation. No roof
vents, though there is an original (1873) arrow-slit type vent in the
brickwork on one gable end.

This is a terrace , so am concerned that ventilation is
maintained.Yes, thre is sarking, hopefully in reasonable nick...
Something local BC seems very keen on as well, as say seen habitable
loft conversions where BC wanted dozen or more vents installed in each
slope in a large semi.


My additional tip would be don't skimp on the detailing - leadwork,
chimney & other flashings, chimney maintainence, gutters, fascias &
soffits etc - get the lot done at the same time.

Oh thats the other half, re-render chimney stalks, properely, some of
the neighbours do show that cement work is a skill and one quite
possible to get very wrong.

Mortar ` water gates` slump mortar at join of chimney and slates and
hope water stays out, they have to go and get replaced with proper
lead/zinc ones.


Get it all specified in the contract, and accept there may be cost
overruns if it becomes apparent additional remedial work is required.
Swallow the cost and get it all done.

Its getting 8 individuals to swallow the cost and realise another
patch up is a waste of money, its about 10 grand + Vodka And Tonic
just for scaffolding , really don`t want a biennial roof patch up
scheme.

Cheers
Adam