Greetings,

My son and his wife have been renovating a 1930s detached house which
they recently purchased, and they have had an early double-glazed
sliding patio door replaced by a modern double-glazed pair of French
doors (installed by Sutton Windows). When this was done the window
installers noticed that the old door had been inset further than it
should have been, and that some bricks on either side had been hacked
away in order to accommodate it.

The new doors (see the picture at
http://www.minda.co.uk/dave/HouseBack.jpg) were manufactured to the
correct size for the aperture but, in order to fit them properly
(i.e.flush with the back of the house) and fill the space where the
bricks had been damaged, the installers used expanding foam to effect a
seal. (BTW, in the picture, the horizontal scar above the first row of
painted bricks is where an external lighting cable originally ran. That
cable has been removed and any holes filled.)

When the house was bought, the mortgage surveyor found no trace of
damp around the patio doors. However, a specialist surveyor did claim
to find rising damp. Consequently, the plaster to either side of the
doors inside the lounge was stripped off to a height of about a metre,
then the walls were treated, coated with moisture-resistant plaster, and
given a new top coat of plaster.

Unfortunately, when it rains hard it is not long before a wet patch
appears on the fresh plaster near the top of the door's reveal (see
http://www.minda.co.uk/dave/WaterIngress.jpg). If the rain continues,
then the patch spreads down the wall over the hours which follow.

Several attempts have already been made to try and stop the water
ingress. Damaged bricks and mortar have had exterior filler applied,
while thick waterproof sealant has been inserted above the corballed
line of bricks where long-standing crack was present. Although the
pattern of the wet patch has changed, water still gets in after a rain
storm and shows through the plaster. Obviously decoration of the
affected area is impossible until the problem has been fixed properly.

Can anyone in the NG offer any suggestions about what can be done next
to diagnose where the water is coming in and how to fix this annoying
problem?

Many thanks for reading this posting.

--
David C.Chapman - )
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