"Ian White" wrote in message
...
Andy Hall wrote:

- Around any chimney stacks there will be either a lead flashing or
mortar benching from the stack onto the slates. Look around the
timbers inside for signs of water penetration or timber decay -
typically wet rot and perhaps weevil damage. From the outside with
binoculars take a look at the condition of the flashing/benching.

- If there is a rear extension, there will usually be a valley where
the roofs join, normally lead. Again look at as much of the timbers
inside as you can and the condition from the outside.


If you can, look in complete darkness for light shining in from outside.
Then look very carefully with a strong light for signs that rain has
blown in - or worse still, powder snow - at any time in the past. Don't
forget to check underneath the more recent loft insulation.

And while you're there, check the topside of the lath and plaster
ceilings.

CUT
Also check the sides of the chimney stack to see if any signs of water marks
running down, if there is you want either new flashing and soakers.
I've work on hundreds of old slated roofs and re roofed a few hundred more.
The main reason for re roofing is that the nails have gone like pins where
they go through the slate holes. You will all ways see light shining
through a none felted slated roof, this is natural, as the slates are never
laid tight together. Welsh slates in there hay day were cut by hand to
size, later years trimming was done by machine. They vary from 1/8 to 3/8 in
width. To keep bond they are laid with varying gaps between each slate. So
as you look at a slated roof from inside light can shine through from all
angles. Snow is sometimes a problem. This was over come by spreading cow
hair mortar , known as touching, on the back of the lath and slate. Now days
underlay felt is used. There are several types of felt from about £9 to
£109 a roll. You only get what you pay for as regards quality. Even some of
these felts have to be vented.

K. S. Notts