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Damp Proofing Question
Sudden rising damp on interior walls around a room
Hi, i hope somebody can help. I'm renovating my Victorian property and last week had the dining room electrics done. At this stage all of the walls were fine. Previously, due to the chimneys and air bricks being blocked, the plaster on one wall had gone popcorny and we had removed it and dried out the wall. Today the plasterer came to patch up the wall. A week ago he had visited to quote me so had inspected the whole room (no visible damp problem). He set up and after about an hour called me downstairs. He said I had rising damp and there was a highly visible tide mark on all three walls of the room (the forth wall is an archway leading into living room) I don't think this tide mark was there the night before and certainly wasn't the week before when he provided the quotation. I've ripped up the floorboards and there is not a leaking pipe and the brickwork and mortar under the plaster seems dry (i have removed a little to check). how can sudden extreme rising damp occur and what should i do next?
this is more likley penetrating damp, caused by failed pointing, a leaky chimney,roof, or an outside drip from a pipe or gutter . that age of property it will be lime mortar in the walls with no cavity or damp course as it is totaly ineffective in that type of building
Answered 30th Jun 2012
Rising damp occurs as a result of capillary suction of moisture from the
ground into porous masonry building materials such as stone, brick,
earth and mortar. The moisture evaporates from either face of the wall
(inside or outside), allowing more to be drawn from below. The height to
which the moisture will rise is determined by the evaporation rate and
the nature of the wall. The normal limit for rising damp ranges from 0.5
to 1.5 metres above ground level.
Rising damp may show as a high-tide-like stain on wallpaper and other
interior finishes, and, when more severe, as blistering of paint and loss of
plaster. Damp walls encourage the growth of moulds, which, with the
high humidity, can lead to health problems for occupants. Externally, a
damp zone may be evident at the base of walls, with associated fretting
and crumbling of the masonry.
Having diagnosed the cause of the damp problem, the obvious response
is to prevent it recurring by fixing leaks, by removing bridges, or by
inserting a new DPC. Good housekeeping measures should be
undertaken as well. These will help prevent further damp problems and
may reduce the severity of an existing problem to an extent that major
works are not necessary. These measures include regular maintenance
of plumbing and roof and guttering systems, and attention to site
drainage and to underfloor ventilation.
Answered 28th Jun 2012
IF THERE WAS NO EVIDENCE OF DAMP PRIOR TO WORK THEN IT IS LIKELY THAT THE WALLS WERE TANKED TO PREVENT INGRESS OF MOISTURE WHICH WAS REMOVED WITH THE PLASTER THIS COULD BE COUPLED TO A FAILED dpc ALSO. yOU SHOULD ALSO CHECK THAT THE CHIMNEY IS CAPPED AND WATER TIGHT AND CHECK THE FLASHINGS AND POINTING IS SOUND.I SUGGEST THAT YOU USE A PRODUCT SUCH AS SOVEREGN HE'YDI TANKING PRIOR TO PLASTERING
HOPE THIS HELPS PAUL BBC HOME IMPROVEMENTS
Answered 29th Jun 2012
This does not sound like rising damp as im sure it would not appear that quick to that extent, possibly penetrating water ingress( from exterior) as you have checked under floorboards for leaks etc. this would probably be the cause of your sudden damp symptoms. has your plasterer checked externally for anything obvious? rising damp would not occur that fast, its a process that takes months to years to get to the stage you have described. i recommend you arrange for damp proofing specialist or experienced builder to access problem further. this is only my guessing without viewing my self.
Hope this helps.(double check for leaks internally).
Answered 29th Jun 2012