Dampmarkings on walls

[northgate house]

I have had a damp proofing course carried out, but I am still getting surface markings on the walls. They are not all at the same heights. Some are above the skirtings (not many). They are mainly at about 1-1.5mts up the walls. Can anyone suggest what this is. Many thanks

 

[Cloudscape]

What kind of damp-proof course is it? Are the walls plastered - if so, with what (gypsum or lime)?

 

[Andrew Bodenham]

Hi, and welcome to the forum.

To get a response you'll have to give more information, such as the age and construction details of the house, internal and external finishes, the exact nature of the 'damp-proofing' work carried out etc. With more details to work on the forumites will be better able to discuss your problem.

 

[northgate house]

Thanks for coming back to me.
The plaster was board finish.
The external walls are rendered.
The gutters are in good order.
The DPC was chemical, injection & tanking.
The skirtings show no sign of dampness.
It is mainly unsightly stainings on the walls.
They are at various heights, shapes and sizes.
One suggestion was salts coming out of the plaster??

Kind regards

 

[Gareth Hughes]

The materials are more important than the way they were finished.
So - walls: Brick, dressed stone, rubble stone, earth, flint, timber frame? Solid or cavity wall?
Plaster: lime, gypsum?
Render: lime, cement?
Approximate age of property?
Any previous damp problems?
External ground level in relation to internal, and surface materials?
Any trees, shrubs, flower beds or other vegetation close to the damp walls?
Any steam or water vapour-producing appliances in the damp rooms?
How draughty are the windows? (draughts are good)
Any open flues / fireplaces?
A damp-proofer may have just taken you for an expensive ride, or it could be a short term problem while the building gets used to its new situation.

 

[northgate house]

Thanks for coming back to me:

So - walls: Brick, dressed stone, rubble stone, earth, flint, timber frame?
Brick
Solid or cavity wall?
Solid
Plaster: lime, gypsum?
Gypsum
Render: lime, cement?
Cement with pebble dash
Approximate age of property?
Circa 1800
Any previous damp problems?
We have had the property 3 years and went through a very expensive damp proofing exercise prior to moving in
External ground level in relation to internal, and surface materials?
There is a pavement & road immediatley to the front of the house, driveway to the left, private road to the right and an hard standing area to the rear
Any trees, shrubs, flower beds or other vegetation close to the damp walls?
There is no vegetation around the house
Any steam or water vapour-producing appliances in the damp rooms?
No only tv's
How draughty are the windows? (draughts are good)
Unfortunately no draughts - fell into a mistake 3 year ago and had upvc fitted
Any open flues / fireplaces?
There is a log burning stove in the front room
A damp-proofer may have just taken you for an expensive ride, or it could be a short term problem while the building gets used to its new situation.
We have problems with the front wall in the front room and a slight mark on the side wall (private road)
There are marks/problems with the dining room wall (private road side and the party wall between this room and the front room)
There are marks/problems with the front wall in the family room and side wall (drive)
I hope this may help a little & many thanks[/color]

 

[MdB]

You miss understood the question about about relative ground levels. What is of interest is if the ground level outside the house is higher (bad) or lower (good) than the inside of the house.

From what you have said, it looks to me as though you have solid wall with a non breathable surface on either side which will stop any moisture in the wall from escaping. Some moisture is likely to have got in through cracks in the paint / render on the outside and some moisture is likely to have got in from high moisture levels within the room (i.e. condensation). The fact that there are issues with internal walls suggest high moisture levels inside is the main issue.

Short term solution:- add ventilation. This will help lower the moisture levels in the room but is also very important for the fire. If the fire can't get hold of enough oxygen to burn properly, it will produce carbon monoxide which isn't what you want. Ventilation equivalent to half the size of your flue is what you want (I believe - not a great expert in this).

Long term solution:- replace gypsum with lime + breathable paint on inside and/or replace cement render with lime + breathable paint on outside.

Damp proofing probably did little to help.

 

[Penners]

When the DPC injection took place, presumably the walls were already very damp. Was the plaster hacked off the damp areas of wall, which were then left "naked" for several weeks, to enable them to dry out?

If not, then your problem may be as described by MdB - trapped damp inside the wall.

 

[northgate house]

A little bit embarrased about this but we instructed the damp proofer to carry out all of the work prior to us moving in (basically one week before).

I remember that the walls (plaster) was hacked off. Whether it was completely hacked off in all areas I could not say.

Once they hacked it off, they did the treatment (????) and then re-plastered the walls.

They left possibably a week before the re-plastering was carried out (may be not even that long).

Over the last 2 years I have also had a plasterer re-skim some of the walls.

So I guess any contamination/moisture that was still trapped in there from the beginning will stll be trapped in there now.

Sounds feasable

 

[northgate house]

If I now hack off all of the plaster - say skirting boards up to 1.5 mts on the 2 front walls, side wall (affected area) to private road, internal wall between dining room and front room & side wall to drive.

Then arrange for the walls to be re-plastered using lime plaster.

Should we treat the walls first prior to re-plastering.

I have seen some sealant products (SBA/SPA) or something like this??

Will I need to take off the skirting boards

 

[MdB]

The whole point is not to seal so don't put anything non breathable on to the wall if you replaster in lime. However, I would try increased ventilation first before going down the replaster route. This might be enough to sort the problem out but give it at least 6 months to work (preferably across summer). Without good ventilation, you will get condensation on the walls as they are uninsulated no matter if they are lime plastered or gypsum plastered.

 

[northgate house]

I have had air vents put into the 3 rooms.

There are now 1 air brick per room.

The windows are upvc (with no trickle vents).

There is 1 window in 1 room that can be put onto a security night opening, in 1 room there is nothing at all (there are no openers on the windows) and in the last room I can again put 1 window onto a security night opening.

Failing that I don't know how I can get more ventilation into the rooms other than putting an extra air brick into each room.

 

[Gareth Hughes]

From what you've said, I suspect that the damp (at 1 - 1.5 m above floor level) is now manifesting itself above the tanking that was applied when you moved in. Not neccessarily "rising" damp, which doesn't exist (to oversimplify), but that's the lowest point at which it can now appear internally. The other replies so far should be enough (if you can wait, and cope with the problem till this time next year) at least to see if it's a seasonal problem. The cement render on the outside won't be helping either.

 

[Penners]

They left possibably a week before the re-plastering was carried out (may be not even that long).

A widely used rule-of-thumb is that damp masonry will take a month to dry out for every inch of its thickness (once the source of damp is removed). So, for example, a 9-inch thick wall will take 9 months. If both sides of the wall are exposed, then presumably this halves to 4.5 months.

Of course, you must take the season/weather into consideration for external drying, when making this calculation, plus the internal conditions in the house. In a poorly ventilated room, drying will be slower.

 

[PC]

You havnt given any indication of whether you have discussed your problem with the damp proofing company who did the work.

I am assuming that you have asked for their commnets and also assume they would be offering some form of guarantee.

If so what have they said the problem is?

Dont go doing anything until you have had it looked at. If your not happy with their response or reasons then come back to me.

Happy to assist

PC

 

[northgate house]

I have been in touch with the damp proofing company over the last couple of years on several occasions.

They have been back and applied:

:?: some kind of pva type (white glue) to the walls
:?: a chemical substance to bring out any salt in the walls
:?: some spray can substance (white on contact)
:?: another coat of pva type glue
hacked off the plaster in one area to expose the damp proofing he originally applied

This was to show me that the area that he had treated was dry

I have since gone back to him, with no response.

I think that the guarantee is not worth the paper that it is written on

 

[conserver]

Hello,
I have just read your post, you mention 'plaster board finish', was that a plaster board finishing plaster or plasterboards dry lined to the wall. Also, what is the floor construction, suspended or solid (concrete). If concrete, any sign of DPM.

 

[northgate house]

This was plaster board finishing plaster (thistle I think).

The floors are concrete.

DPM??

Thanks

 

[Schoolmarm]

DPM =DAMP PROOF MEMBRANE

 

[conserver]

Sorry, DPM-Damp proof membrane, should be found in more recent solid floors beneath the concrete slab or sand/cement screed, acts as a moisture/dampness barrier. If DPM is absent, this could be the cause or one of the causes for the defects you describe.