On Jun 8, 2:18 pm, "Phil L" wrote:
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/4vso3j
http://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?

Thanks for your thoughts
Calum

upon closer inspection of your pictures, iut seems to me that the water
isn't coming down the inside of the chimney but down the outside.
Am I correct in assuming the walls have been dot&dabbed? - these wet patches
look like DL adhesive to me, and if they are, then the water is coming down
the face of the brickwork that they are stuck to (which it must have been
doing BEFORE it was covered up! *) and the water is going through the
adhesive and into the plasterboard.

*Which begs the question, why did anyone cover up an obviously wet wall?

mmm if there's so much water coming down the outer surface of the
chimney breast to soak thru pb dabs placed here and there - shurely
there'd be some other evidence of *lots* of water getting in - in the
room below the loft conversion perchance?

OP - can you orientate us and tell us (somehow) where the c breast is
relative to the stack in the pics? i.e. specifically what part of the
chimney stack is directly above the damp area? are the damp spots in
pic all there are in loft? or are there more? any signs in lower rooms
(yet)??

Jim K