Possible damp problem after skim

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Hi there everyone. Hopefully I'm posting in the right place, apologies if not. We recently had the majority of our house re-skimmed and are very pleased with the finish. However, in our porch, there is one spot about half a metre long and 5 inches high going up from the floor that still hasn't dried out. It's been about 16 days since he finished it now. The porch has dried out just fine, apart from this spot. What worries me is when I took the old skirting board off in this area before our plasterer did the job it was pretty rotten, so I'm worried there's a damp problem in the wall. Our plasterer had some filling in to do before skimming and he used sand and cement on the interior of the wall in question. There seems to be some salt forming just above the wet patch too. Should I just wait it out to let it dry or should I call him to take a look? Thanks in advance.
If its rising damp then its not his fault unless he plastered down to the floor.get it damp proof injected.you can buy in tubes now and inject with a mastic gun into the mortar bed.
I expect there was a damp problem all the time, the plaster possibly should of been hacked off up to 1.2m high and two coats of waterproof rendering applied, remember skim is basically a decoration but does not aid structure or dampness. Finding the cause of the damp , blocked drain ,broken drain ,leaking gully.ground higher outside, ps a plasterer rendering down to a concrete floor can cause the damp to climb the wall , plastering to a wooden floor has no effect
My dad had similar on an outside wall next to the bay window. The drain pipe outside went straight into the garden and fed a pipe across the garden and under pavement onto the road. These used to be open metal gullies with a slit so crap cold be scraped out - now they are tarmacced over and be road height is level with the outflow so they get blocked. What caused his was the pipe in the garden was ruptured so water backed up, spilled out the drainpipe and soaked the outside wall. I hacked off the old plaster then rendered and plastered the wall but was damp for a while till he fixed the pipe. A good coat of Thompsons water seal was put on as well outside. The damp hasn't come back. (I left a few days for the render to cure btw)
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Is the porch single brick?. Dont got injecting fewk all till you've had someone who knows what they doing look at it marra
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It must have been damp before, dry wood won't go rotten.

Time to get the damp companies round to quote.
leave it and see what happens the damp spot could be from where he's used sand cement and it's taking longer to dry, the salts are damp let it go till after Christmas try sealing it with something that deters moisture from Bandq then if it's still bad it's time for a rethink
One job I did was on an internal wall that was damp on both sides and skirting was rotten. There had been a doorway there and some cowboy builders had filled it and rendered - right down to the floor! It was also a stone floor. The couple got a damp proofing firm in to check it and they agreed with me it was a bridging problem.
To cap it off the cowboys had used bin bags as dpm on the external wall which were now disintegrating. I hacked the plaster off and redid it leaving a bridge, years layer and still no damp.
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