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Damp Proofing Questions

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1,422 Damp Proofing questions

Damp patches appearing on bedroom wall to front elevation and side wall.

I live in a terraced house built about 1910. One bedroom sometimes gets had black mould on the PVC window frame which washes off easily. Recently I've noticed grey and black patches on the walls in the corner of the room - some to the front wall and some to the side. The wallpaper seems to be lifting in this corner too.
The front elevation is brick and tile I believe and the side wall adjoins next door. I have checked the attic which is insulated and can't see any dampness to the plasterwork on the wall above the area of dampness in the bedroom. Can anyone suggest how what this is and how to remedy it?
Thank you.

Black mould since PVC double glazing fitted.

Hi - seeking advice regarding a purpose built 1960s ground floor flat which has suffered condensation and black mould in the outer corners of the walls and low on the outer walls since PVC double glazing was fitted, replacing the original wooden single glazed windows. Filing under 'Damp Proofing' but not sure if there is a better category.
The first thing tried was to make sure the trickle vents were open - they were and they are. Then since no ventilation was fitted in kitchen or bathroom extractor fans were installed, the bathroom unit follows the light switch, i.e.no timer, the kitchen extractor just on a pull switch.
There being no improvement and the flat remaining very humid a Passifier vent was fitted low in the outer wall of the worst affected, and coldest room.
The last recommendation has been to fit a Flatmaster 2000 Low Energy Positive Input Ventilation Unit but this advice has not been taken up. The above work was all recommended by ventilation specialists. Lastly the occupier's lifestyle was blamed for the trouble, being out all day and leaving the flat unheated, in addition to running a cloths drier in the bedroom, albeit vented out of an open window.
The flat has wood block floors over concrete and has recently been inspected by a Chartered Surveyor who pronounced it to be structurally sound.
The property now needs treatment for the existing mould and considerable investment in full refurbishment. We plan to include a humidistat extractor in the bathroom this time, and an extracting cooker hood over the kitchen hob, but no plans to go for the Flatmaster.
My worry of course is that all this will be for nothing and the mould will return.
What advice would you give please on the Flatmaster, or any other device or method we could apply to maximize our chances of success?
Thanks for your attention, your advice eagerly awaited.

28/11/14 -
Lee - Many thanks for your feedback, I was not aware of systems like that and it looks very effective. Much obliged, thanks.

Damp in upstairs chimney breast of old fishermens cottage

I am in Bognor and have damp issues in the upstairs chimney breasts.

I had the local roofers in who thought the problem was 99% to do with the lead flashing, so these were replaced. However, when they did this work they said they thought there was an insufficient overlap in the slate tiles and recommended that the roof should be re-tiled, and one of the redundant chimney stacks was removed. The work was completed May 2014.

Despite the exceptional summer the damp still appears to be in both chimney breast (they have brought a damp meter to confirm this). The chimney breast which remains has a gas fire fitted downstairs and an ornamental cast iron fireplace in the bedroom which is not used. The roofers came to inspect the interior of the chimney the other morning and said that there was a very high amount of water (condensation) in the chimney. I have read that use of a gas or log fire may cause fumes that will give problems with condensation, but the gas fire has not been used since the roofing works had been completed, so cannot understand this could be why there would be condensation. The heating had not been on that week, so the only air going up the chimney was ambient temperature from within the house. They did the inspection around 7:30am following a dry night.

From your experience is there anything else to consider? Could the fitted gas fire have any effect despite not being used since the roof repair??

The house is around 1870 and is an old fishermens cottage. The chimney is rendered and they have even applied a damp proof solution to the render. The roofers are a reputable local company, but are struggling to come up with an answer. They were going to speak to a local company who supply and install gas fires, and have suggested a vent in the roof over the taken away chimney stack.

Damp proof specialist have suggested a tanking option to the breast.

Many thanks in anticipation of your advice.


Damp spots in living room - replaster or something more serious?


I'm having a problem with some recurring spots of damp in my living room. I live in a terraced house, and it's about 100 years old. The damp isn't pervasive - if anything it's just tiny little spots of wetness which most people wouldn't notice - but I'm keen to get it sorted if possible!

The damp patches occur around the mantelpiece of the fireplace (on the chimney breast), and in the two alcoves either side of the fireplace, mostly around two plug sockets. It's limited to the very bottoms of the wall and doesn't reach higher than around half a meter. The walls here are very cold to the touch. This wall adjoins to the next house in the terraced row. The skirting boards don't appear to be affected and aren't crumbling at all.

The walls in this room have been papered before painting and the paper is becoming warped at the edges where the damp spots are. We only noticed the problem when we repainted the room from cream silk emulsion to green matt paint. We've tried damp proof paint, which has held the spots at bay for a few months, but we've just turned the central heating off for summer and the spots are instantly back. They dry very quickly if a fan heater's directed at them though! Think it gets a bit worse when it rains but again, dries up quite quickly apart from a few stubborn spots.

Does this sound like rising damp, or another kind of damp? As it's an old house, we don't think it has a DPC (we know the walls are lime), but before moving in we had new air bricks put in to allow better ventilation and the sub-timbers cut back so they weren't touching the walls of the house. This was costly in itself so we're hoping there may be an easy (ish?!) answer to stop the spots coming back. Would re-rendering and replastering do it, or do we need to try something more drastic?

Any ideas would be great! Thank you

Rising Damp in hallway


We have had a little bit of damp in our hallway ever since we moved into our 1900's terraced house over a year ago. Since moving in, the damp has fluctuated between dusty on the wall to a 'damp' wall. The wall in question is the wall between our house and the next, and recently, the floorboards underneath this damp have started to go. Do I need a builder ASAP. as we can't really afford one now? And also, is there anything I can do in teh meatime, other than trying to make sure the the doors to the hall are open so that the damp dries out a bit?

I would be greatful for any help!


Tanking behind skirting

Is it necessary to tank behind the skirting when the job is being done. Also is it possible to just do patches of tanking on a wall?

Damp/watermark on wall (about half way up stairs)

When we took the wallpaper off the walls on our stairs some of the paint behind it started peeling away. I removed most of the paint from the area and there is a watermark on the wall and the texture is different there than other parts. This is about half way up the stairs. I then removed the wallpaper from the area under the stairs (which is directly under the watermark) and it came away easily as it was very wet. Under the paper was a lot of black mood. Is this a sign of rising damp?

How do I know if any DPC has been injected at all?

I have had an injected DPC performed 4 years ago and the damp keeps coming back. It is at it's worst yet this year. I noticed other houses seem to have a residue around the drilled holes, presumably an over-spill of the DPC? My property has the holes but no residue. How do I know if anything was injected?
The property is of solid wall build circa 1910. damp is at bay window wall.


Understanding damp meter readings

Hi, I'm having difficultly in a flat I'm privately renting from damp issues, possibly condensation but after doing everything (heating, ventilating, dehumidifiers etc) not solving the issue, so I have just purchased a 4-pin damp meter.


Sadly it has no instructions on how to interpret the readings and searching the net seems to leave to leave me confused although I did read this somewhere:

Normal (< 10% to 16%), attention required (16 - 20%) and Action required (20-28%).

Is that accurate and how would this testing equipment really fair on walls?

I have taken a few readings with the walls I'm concerned about and it ranges from 20 - 26% even from top to bottom, I took a reading in a room not so bad at around 10-12% top to bottom.

Thanks for any help you can give me.

damp patches and rising damp in badly pointed extension

We have just moved into a semi detached property and the exterior side wall of the extension is very badly pointed meaning damp seeps through and can be seen on the internal walls. There is also rising damp present. One builder recommended the most cost effective way to deal with this is to plaster the entire outside of the wall and add some kind of damp proof treatment to the plaster or paint over the plaster with damp proof paint. Is this the best way to deal with this problem?

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