Adam Aglionby wrote:
On 7 June, 07:22, Calum wrote:
Hello all

I've just had a loft conversion completed on a victorian semi. The
rear of the house is one large dormer with a (nearly) flat roof, and
we've left the chimney stack in place as we might use the dining room
fireplace one day.

The problem we have is that rain is getting in somewhere and coming
through the chimney breast plasterin the new loft room, but the roofer
can't work out where this is coming from.

Here is a picture of the plaster with a roll of masking tape for
scale. There are pencil lines around the damp circles as I was
measuring to see if they got bigger.http://yfrog.com/7bixtj

Here are pictures from the outside:http://yfrog.com/4vso3jhttp://yfrog.com/6ds5mj

The roofer has re-pointed and patched up the mortar slope to the (very
old and unused) central heating cowel. The cowel was covered in a
plastic bag, but that made no difference.

If it rains moderately for an hour, the patches appear/get worse and
then take a week or two to dry out. To me that looks like the water
is being funnelled down quite effectively.

Could it really be soaking in from the brick? What else could it be?

TBH flashing looks pretty normal, read lead/zinc for copper here

http://www.copper.org/applications/a...s/chimney.html

Would normally think flashing failure giving damp signs higher up wall
or on ceiling as water runs down outside of stalk internally.


NOT if iuts been RENDERED internally. It will then migrate behind the
almost waterproof rendering via the mortar - particularly lime or weak
mortar - till the rendering stops. Then the plaster will suck like crazy.




Brick has lready suffered water damage, the damaged faces look as if
damp has penetrated behind then frozen and blown the faces off.

Stack looks like its beginning to split as well, silicone sealant is
great but structurally gluing split chimney stack back together from
outside is probably pushing it.


Indeed.

Demolish and make good seems best option if don`t need vents and can
get [planners to agree, take down and put back together again
properely if they don`t.


Well we agree on the ideal solutions, anyway.

Looks a bit far gone for this sort of treatment to work, water
proofness on lot of bricks has gone.

http://www.rkiroof.com/id74.html

I ferking hate roofs, its all down to opinion and any of them, in any
combination could be right.


nah. Rooves is great until people wot don't unnerstand em start ****in
wiv em.

I had a leak..on the new tiles..builders looked, and said '******* Dave
didn't do soakers' and he was right., a little slip of lead=no more leaks.


There are right ways, and ways that simpoly dont work.

It needs taking to bits and doing right.


Cheers
Adam



Thanks for your thoughts
Calum