damp patches

bltchef

Hi could anyone help I had damp prof course about 8 years ago now in my dining room I have notice a damp patch on the wallpaper its 3 ft off the floor and about 3 ft long the paper feels damp it not an external wall any suggestion I thing the compant who did the work has gone under :beer:

Tucker

There are some good damp experts on here who I am sure will offer some advice.

If it's an internal wall, it doesn't sound like it's relevant to the damp proof treatment. I am assuming this particular wall was not treated with it not being an external wall? Is the wall solid or a stud wall?

Is there any pipe work within this wall that could be a cause?

bltchef

they is no pipe work behind and wall it is a solid brick wall it was treated at the time

David_Aldred

Hi bltchef,
Being an internal wall makes it highly unlikely to be condesnation and obviously not penetrating dampness in addition to you ruling out leakage of any concealed pipes within the wall.

A horizontal line of dampness to the plaster / wallpaper at the junction of where the re-plastering associated with the remedial damp proof course you had done 8 years ago (often but not always around 1m high) meets the original remaining plaster above this level, correlates with a number of things.

One of these reasons may (although not confirmed to date in your case) be continued rising dampness up the wall and this being held back at lower levels by the often harder denser (compared to original plaster) remedial re-plastering so it takes the easier option of jumping above this level, evaporating from this point and leaving behind ground salts that themselves alone can make the wall appear damp. Alternatively another reason can be that the original hieght of remedial re-plastering was not taken high enough and as the wall dried down an accumulation of salts migrated from the wall into the plaster at this point. Again if the salts are hygroscopic they will attract moisture from the air to them in the same way leaving table salt out in a kitchen may become damp.

In any case the problem, now that it has occurred is unlikely to recover and will require investigation to determine if rising dampness is still occurring, this to be resolved if it is, determine what type of salts are within the problem area of plaster (i.e. salts from the ground or from some other source) as this will assist diagnosis and likely removing of the degraded plaster well beyond the last sign of the problem followed by re-plastering to an appropriate specification that includes being able to hold back salts within the wall.

I know you state there is no problem at lower levels but I would, as a precautionary measure also check the moisture content of any wood to this wall (such as skirting / door frames etc) to see if it had a raised moisture content and consequently was at risk of decay. Hope this helps, kindest regards, David Aldred Independent damp and timber surveyor.