Damp patch on wall, advice please

17 Nov 2012
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United Kingdom
Hi, we have a damp patch on one wall in the front room (see pic). When we bought the house we painted over it but after a particularly wet week the mark came back. The mark is on the wall between the previously external wall and the conservatory. There is no mark on the other side of the wall (inside the conservatory).

The survey we had on the house said this:

"Damp areas were found at low level to the rear east wall in the living room to the right of the French Doors with damp staining present to the plasterboard dry-lining and also the understairs cupboard with efflorescence obvious to the exposed brickwork possibly caused by porous masonry, exposed location and defective flashing to the conservatory. We were unable to determine the exact cause of the dampness and as this is serious you should instruct a Property Care Association (www.property-care.org/) registered company surveyor to inspect all areas of the property"

Images of the conservatory flashing attached.

Does anyone have any suggestions of things to try before getting a costly damp survey?



Photos added:

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There was no picture!

I am no expert, but from what I have read on lots of forums, I will help you as much as I can.

Damp can be cause by bridging the cavity between the outer and inner skins of brickwork. This can be causes by rubble or material being knocked into the cavity. It is possible that this was done when the conservatory was fitted.

Also, if the conservatory wasn't sealed and flashed properly then water could run down the external face of the wall where the conservatory was fitted.

Perhaps try:

1) Ensuring the conservatory is properly sealed to the external wall, refit flashings and seal with silicone.

2) Make sure the guttering is clear and doesn't back up.

3) Perhaps paint the outer face of the wall with some sort of sealant.

I doubt you can access the cavity, but clean that out if you can.

I hope this helps, if not then you need to get an expert round.
Thanks gissle, I was thinking so sealant might be a start, I'll give that a shot.
That flashing is a joke. Its not doing anything and should be over the top of that end roofing bar, not behind it.

Your surveyor is an even bigger joke in not diagnosing the problem, but referring you to someone else. I'd ask for a refund.

As for the problem, if it's not the flashings, then it's because there is no cavity tray fitted in the house wall to cast water out of the wall above the conservatory roof, instead of it running in the wall and into the conservatory room
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Now the photos are there, I see what you mean, the flashing should overlap the conservatory roof - not go under it! It's just redirecting water under the roof!
That flashing at first glance looks like lead but I suspect it is grey plastic shapes, not even chased into the brick work! cosmetic.
Thanks guys,

The flashing is plastic.

I've had a good good with a generous amount of silicon sealant so we will see if that helps.Thanks again.
We've not really had any change yet. We have put sealant along half the adjoining conservatory roof, the other half to go... it's not done anything either way.the damp isn't getting worse, which given the weather (floods down here in the south west) is good. We are going to finish sealing it all up and then try get it dry through the summer and hope it doesn't come back. Short of getting a damp survey done £200 I'm not sure what else to do.

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