Jim K wrote:
On Jun 7, 12:05 pm, The Natural Philosopher
wrote:

I take it the flat roof is part of the new conversion? If so its been
badly done.
care to expand - for the benefit of the OP?
I thought I had..

I don't like the way the flat roof has been sealed to the chimney. It
looks inadequate.

Water can run down the sides inside, and appear ..well wherever there is
a route. Probably through porous mortar.

your last critique appeared to me to be a general "crap flat roof"
broadside so was hoping you could enlighten the OP with specifics taht
he could use to bolster his possible arguments with the professhunals
who did it - seems all you are picking at is the height of the stack
flashing and what may or may not be underneath it...


Well all flat roofs are carp, because simple overlapping of waterproof
elements will not in general be enough, as water can and does work its
way between the layers in any sort of wind.

The whole point of a roof slope is to make gravity work for you against
wind pressure.

Typically what you might do for a stack is to create a flashing,
soldered together that extends a LONG way from the chimney base

And run the felt up inside it..but then the corners are vulnerable as well.

So you probably end up with some sort of 'soaker' system. a lead layer
under the felt, the felt and a lead layer over it, and all raised up at
the stack, so that water has to run up the felt under the top lead, then
down the lower lead and a long long way before it ends up dripping off
the edge of the soaker through the ceiling..so put another layer of felt
under hat as well that goes all the way to the flat roof edge etc. And
seal it all with flexible mastic and pray.

It's a series of defenses in the end, all compromised by the fact that
gravity on a flat roof is just as likely to make water move towards the
places you don't want it, as the places you do.







Jim K