Damp Patch - Internal Wall

imroberts · 19 Jun 2017

My house is a 1930s semi-detached which I have owned for about 4 years. The internal decoration was in poor condition and the (original) plaster was crumbling off the walls, so I chiselled it all off and had the whole house dotted and dabbed.

One small patch of the lounge wall developed a damp patch. I ignored it initially thinking it might dry out but 2-3 years later it is no better. It seems to worsen through the summer which I'm assuming is probably just down to having the heating on through winter and so assume the problem is constant.

I've attached a picture to show the issue - the wall in question is an internal single skin brick wall approximately 6 feet from the nearest external wall - the other side of the wall does not appear damp, and the brown wall to the left (the side of the chimney breast) also does not appear damp.

The damp definitely appears to be rising, rather than down the wall as a leak, for example, would. However logic dictates if it was rising up the brickwork I'd see damp on the other side? I'm at a complete loss as to where to start, and don't really want to call in a "damp expert" without any knowledge what to expect.

Any thoughts?

terryplumb · 20 Jun 2017

hi ,your pic isn't the best ,at least on my kit, but appears to be damp patch on right ,at skirting level, next to architrave. is your floor wooden with crawl space below ,or concrete ? on left side of pic ,are there central heating pipes that are "boxed in " ?? do you have condensation problems anywhere in they property.??,.,..............................
..
edit..by the way how wide and how high is the affected area ,can't tell from pic ?

imroberts · 20 Jun 2017

Thanks for replying. I'm struggling to get a decent pic of the area if I'm honest - I've tried again and have attached a marginally better picture.

In answer to your questions:
1) Yes, the damp appears to come up in two places, one further left closer to where the boxed in section is, but the bit next to the architrave is by far the worst spot of the two. The width of the affected area is about 1ft and the damp rises to about 6" above the top of the skirting.
2) Yes, there are central heating pipes boxed in along with a bunch of cables.
3) The floor in the affected room is wooden with space below. On the other side of the affected wall is a concrete floor.
4) No condensation, damp, or mould anywhere in the property.

terryplumb · 20 Jun 2017

when you say wood floor and space below ,is it a few inches or feet ? is the other room with concrete floor ,on other side of wall ,an extension or a kitchen ? and final question do you ever get condensation forming on the inside of glass windows anywhere in property ?

imroberts · 20 Jun 2017

From memory the floor void is about a foot deep, maybe slightly more. The room the other side of the wall is the kitchen.

Nope, no condensation anywhere in the property. Not even in the bedrooms through winter when all the windows are closed.

terryplumb · 20 Jun 2017

i think you may have a combination of two problems, condensation and rising damp. when " dot & dabbing" onto bricks that have absorbed moisture ,the adhesive between brick and plasterboard draws moisture from brick into plasterboard. if you rap your knuckles against the wall you will find it solid where damp patches are and more hollow sound where drier .try it and let me know. i can then offer a solution.

vinn · 20 Jun 2017

OP,
Are you saying that both sides of the single skin wall in question have been D&D'ed?
Have you examined the floor wall/skirting abutment below the carpet?

What your pics show is not condensation.

Damp internal walls with chimney breasts can often trace the cause of damp to the chimney breast:
Either from sooty flue salts spreading sideways or rising damp from the earth fill below the hearth.
The solid floor could be "bringing up damp" which is finding it easier to display on the opposite side of the wall.
Does your suspended floor have air bricks on two sides??

Why not post a pic showing the whole chimney breast?

imroberts · 21 Jun 2017

Thanks both.

terryplumb said:
i think you may have a combination of two problems, condensation and rising damp. when " dot & dabbing" onto bricks that have absorbed moisture ,the adhesive between brick and plasterboard draws moisture from brick into plasterboard. if you rap your knuckles against the wall you will find it solid where damp patches are and more hollow sound where drier .try it and let me know. i can then offer a solution.

Yes, it does sound as though there are two dabs of adhesive roughly where the damp is at it's worst, and it does sound hollow in the middle where it's slightly less damp, which rings true with what you're saying. What's interesting is the other side of the wall also appears to have at least one dab of adhesive at skirting level directly opposite this patch, yet that side of the wall is not displaying any signs of damp?

vinn said:
OP,
Are you saying that both sides of the single skin wall in question have been D&D'ed?
Have you examined the floor wall/skirting abutment below the carpet?

What your pics show is not condensation.

Damp internal walls with chimney breasts can often trace the cause of damp to the chimney breast:
Either from sooty flue salts spreading sideways or rising damp from the earth fill below the hearth.
The solid floor could be "bringing up damp" which is finding it easier to display on the opposite side of the wall.
Does your suspended floor have air bricks on two sides??

Why not post a pic showing the whole chimney breast?

Yes, both sides of the wall were D&D'ed at roughly the same time when I bought the house.
No, I was hoping to gain some knowledge and try and figure out what I was looking for and what the possible solutions might be before I started pulling the carpet up. What do you suggest I'd be looking for in examining the abutment?

When you say the solid floor could be "bringing up damp" - the floor is covered with laminate which I'm keen not to start ripping up unnecessarily, however I can get hold of a damp meter and should be able to take a damp reading from the concrete roughly a foot to the side of where this patch is - would that be worthwhile?

I'm not 100% sure on the air bricks but I can check when I get home and also post a picture of the whole chimney breast if you think that'll be helpful.

imroberts · 21 Jun 2017

I've checked and there are two small air bricks on the front of the house and one on the side (but still fairly near the front of the property) which appear to both go under the lounge floor.

I've also attached a photo from further back showing the full width of the chimney breast.

terryplumb · 21 Jun 2017

think you need to remove skirting and have a look as vinn said. it s impossible to be certain exactly what the cause is with the pics and info available ,it needs further investigation . if it turns out that the dpc has failed the following product is an easy to apply dpc injection cream ( emulsified silicone ) which is injected into the mortar , after drilling some holes.,with a standard cartridge gun. it's called "PAM CREAM" dpc injection cream.the company do mail order tel 01942 887920. company is PAM TIES ltd.

vinn · 22 Jun 2017

Thanks for the photo.

The carpet can be lifted quite easily off the grippers, and there's no call from me for you to go "ripping up" anything. Perhaps leave the carpet alone.

What you can look for with very close observation, and by sniffing for a musty smell close to the skirting on either side, are signs of damp in the floors or skirtings.

The general impression from the pic is pretty much everything is in order, so to speak.
So perhaps simply paint over the present damp signs and wait and watch?

imroberts · 23 Jun 2017

I've already painted over the area and the damp patch simply came back pretty much straight away. I don't anticipate being in the house more than a few years and the patch is prominent enough to put off prospective buyers in the future so I'm keen to find a solution.

Looks like I need to take up the carpet in that corner to have a better look and see if the floor is damp - there are some loose floorboards within a couple of feet which should get me a view under the floor to see if there's anything obvious under there.

terryplumb, are you proposing that I could simply inject some DPC cream in that 1ft stretch of wall, given the problem isn't showing itself anywhere else? Would I be better trying to inject that in a mortar course below floor level or would behind the skirting be sufficient?

One other thought I'd had given the area is only about 1ft wide and the damp is only making it's way up about 6", is I could relatively easily cut out a section say 12" or 18" high and replace with foil backed plasterboard? I know that's recommended for solid external walls presumably to cope with similar problems. Would that seem a sensible option?

terryplumb · 23 Jun 2017

it can be done behind the skirting.

terryplumb · 23 Jun 2017

by the way ,when you painted did you just emulsion it ? I have used ronseal one coat damp seal in the past and it's quite good. you paint it on the wall ,and when dry apply your top coat .of course this only "masks "the stain it does not cure an underlying problem. don't think you can dot and dab foil backed p/board ,but i may be wrong. some years ago when i was buying property's to renovate I came across an issue very similar to yours in a terraced house. small section of wall between dining room and kitchen ,and right next to door casing ,but no chimney ,it was at right angle to external wall. applied the Pam ties dpc ,cut p/board out about 18 inch high ,applied sand /cement render with a waterproofing additive. then had the wall plastered. kept the property 5 years tenanted and never had any reccurance. I also bought the house next door but one, no issues with it ,had all walls dot and dabbed in the dining room, roughly 18 months after the tenant moved in ,damp patchs appeared .roundish shape 6 to 8 inchs ,and about 2 foot up from floor level. and only where the adhesive blobs where behind. all we did there was use the ronseal stuff. and it was good for 2 years ,then started to show thru again, by which time was ready for re paint anyway. still own it now actually , same tenant in fact.

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Damp Patch - Internal Wall

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