In article , Tanner-'op
writes
George (dicegeorge) wrote:
There are lots of slipped slates on my roof, with rusty nails,
the local builder recommends reslating the whole roof
rather than patching it again and again.

A good decision.

At the moment there is no felt, he advises felt,
is there any reason not to use felt?

There is every reason to *USE* felt. The main one is that if a slate slips
or breaks then the felt (if properly fitted) will prevent water from
entering the roof space until the slate can be replaced.

Totally agree, a failsafe (faildry?) system has to be better than one
which allows damp ingress on a single point of failure.

or is there an even better option?

A close boarded roof with felt and slate (Welsh slate being the best) but
the cost will frighten you! :-)

I thought all slate roofs were close boarded but that's what living in
Scotlandshire does for your perceptions. If cost isn't an object and you
might insulate or convert the loft later then a breathable membrane in
place of felt would be a further improvement. Any (unlikely) damp
ingress below the membrane would have a chance of escape in warmer
weather, saving timbers from potential rot.
--
fred
Plusnet - I hope you like vanilla