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Damp Proofing Questions

Our expert damp proofers have kindly agreed to share their wisdom on such topics as removing mould patches, rotten timber, causes of mildew, damp basements, rising damp, floor construction, flooding and waterproofing and much more.

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1,119 Damp Proofing questions

We have a 19th C house with mould that effects only on one side of the house. Brick work seems pourous. Insulation problem?

We think it could be effected by outside wall of house and poor drainage from next door neighbours driveway which runs against the wall? Is this possible?

hi. Im having problems with an external wall in my three bed semi bungalow. There are two areas of damp. one rising and one coming down from the ceiling

Sorry, just read my question again, its the internal skin of a cavity wall not external. Thanks

My bungalow is built on a hill and has an intergrated garage beneath. The wall thats damp is above the garage. A section of the garage ceiling is missing (where the rest is fire proof sealed) im wondering if this may be where the rising damp is coming from?? although i have knocked off the plaster and everything appears dry, though the plaster was very heavily moulded. seal the ceiling and re plaster??????

Also when the weather is wet moisture appears two penetrate through the mortar beds, i can see every line on the blockwork on the internal wall. Will vents cure this????

In just one of our upstairs bedrooms the walls keep getting black mould and the plaster/paintwork is becoming mottled.

What do you think is causing this and what would be the treatment - the downstairs / other rooms are not affected

How to fix a damp wall

The front room wall, that is also the outside wall, has had damp appearing for the last year, ever since I had some boxes lent up against it. Now the wall has gone bobbly in places and yellowy, and is cold to the touch and clammy. There are cracks appearing too, but all just coming up from the bottom up to around 40 cm from skirting board.

Whats the best thing for sorting it out? Painting Anti damp stuff onto it, or will that cause it to spread further up the wall.? Or do I need more specialist work done on it?

My neighbour and I have a problem with penetrating dampness on a gable wall. Was wondering what the best option would be?

We have had a couple of builders round to give us advice and quotes. One builder recommended K-Rend and another suggested roughcasting. Which would be the best option to go with?


i am looking to buy a property , it has a high damp reading on the chimney Breast in the bedroom and you can see a mark running from the top of the chimney Brest to the bottom

survey says their is a high damp reading on the lower floor , the house has been empty for some time

Old stone mid terraced house with damp patches on bedroom walls and ceiling.

I have an old stone mid terraced house which I let out (just one so not a big property tycoon). My tenant is complaing of damp patches on the bedroom walls. I have been to check it out with the jointer builder who does bits for me. The gutters are not leaking and had a membrane fitted last year between the roof tiles and the gutter to preven water running onto wall. The tiles are intact. He cannot see any problem with the pointing. We tried to explain to the tenant that it is an old house and that it needs to be ventilated, we told her to open the window regularly and not to dry washing in the room. We discussed the position of wardrobes up against the outside wall and how it will cause damp patches. My man said the only way to really get rid is to strip off all the plaster and have batons and insulation, plasterboard and platering. Which he thinks will cost at least £800. I said it is too much at the moment. In the end he suggested adding some more membrane onto the gutter into the house next door just in case, providing a de-humidifier which I have done and also suggested that insulating the loft may help which I have arranged a quote for. Do you think loft insulation will help or make the problem worse, some of the dark patch is on the ceiling in the corner? Thanks.

I have had salt blisters around 3 internal Walls slowly got worse over the last 10 years. Does this have anything to do with the stone / concrete skirtings that remain from when the house was built?

terraced ex council house
60 years old. Only affects one side of the wall.
Blisters are above masonry skirts go upto about a foot

Laying engineered wood in basement flat

I have commissioned a flooring company to lay engineered wood flooring in an old basement flat.
The previous solid wood flooring buckled (however there was a burst pipe to the rear of the property which has now been fixed).

As the floor was old, damp and uneven the flooring company have
1) Used a PVA and then a self levelling compound (Universal Setcrete )
Their next steps are to
2) Lay a liquid DPM wait for this to dry
3) Lay a plastic sheet, then put a fibreboard underlay
4) Lay the new engineered wood flooring

However, I was concerned as 36 hours later the self levelling compound is not fully dry. It was supposed to take 3-24 hours. As such I had a look at Universal setcrete website and it states a DPM should have been laid beneath the self levelling compound.

My question is - who is right? Should the DPM be laid before or after the Self levelling compound?
Should I ask the flooring company to take up the self levelling compound and start again by installing the DPM? Should the DPM be liquid or physical? My surveyor had suggested Oldroyd xs rather than a liquid one to prevent human error causing cracking.

What are the solutions to condensation problems causing damp?

Thank you to Your Builder for answering my last question, you were extremely helpful!

If the damp issues in my house are caused by condensation, then there is an issue with heat and ventilation. A few years ago we had small damp problems in two rooms but now it is everywhere, what reasons could there be for this change? (the only thing different about the house is it was replastered and painted).
Also, if having a correct balance of heat and ventilation will solve the problem, how do I create that balance? Is there something I can get to stop the damp from growing more than it is now and also prevent it from re-occurring?I have tried opening the windows more often as I read it would help but this, and trying to change the heating, isn't very practical in this cold winter. I read condensation problems occur more in winter times but many houses do not have damp issues and both our neighbour's houses are fine, so I wanted to know what's the difference in our house that is creating the damp and mould. I understand that there's a limit to how much you can figure from just a post like this but any more information/advice would greatly be appreciated!
I just don't understand how to have that balance because the air/temperature inside the house is always going to be different from outside and winter comes every year, it's not easy to notice the damp growing behind furniture until it gets really bad, and we can't be checking for damp everywhere every day and repainting to remove the stains when we do manage to clear it off (only for it to come back though).

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