"fred" wrote in message ...
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.

Except a single point of failure (a single slate slipping) does not result
in a leak unless the slate below is also faulty.

Anyway I fail to understand the reliance on a material with a much
lesser life than the 100 years plus of 2 layers of slate.

OK there are now better materials than traditional felt.

Jim A