New plaster / damp? Ask your questions and find answers on many subjects relating to plastering and dry lining

[Paul B]

Recently had a wall suffering the effects of mild damp repaired (internal wall coming in 90 degress from external facing walls) - Victorian property.

So, on the wall, both sides were hacked back to the original brickwork, which had patchy damp areas. The wall was injected with a chemical DPC, then a waterproof bonding sand and cement applied to both sides, then skimmed. All seems straighforward. However, the walls both sides were decorated soon after the bonding / plastering was completed - and in one area, the area most likely to remain cold and away from direct sunlight indicates dampness on a calibrated damp meter on the surface of the paint (i.e not digging pins into plaster).

Now, the paint had a layer of undercoat applied, and is a bathroom paint (as this is a small toilet area).

There are no visible indications of dampness, i.e bubbling, discolouration, flaking, salts - bit just a reading on the meter and cold to touch.

It drives me mad, so is it just the moisture coming through that area of the wall from the bonding/replastering and will dry over ime, or shoudl i be more concerned?

Any thoughts, advice gratefull received.

PB

[TheDoctor4]

Hi

Have you ahd a look at the DIY Projects area of DIY Doctor at all: https://www.diydoctor.org.uk/projects.htm There is a project called "Damp proofing - replastering" that may provide you with some helpful information

Regards

[Paul B]

I did look at this, not sure it helps, just wondered if anyone has some advice/thoughts from their own experience, understandiong - I am wondering if it is just the plaster and bonding mix all drying through?

[kbrownie]

Hi, not really knowing your layout and the chances of water ingress from else where. So it is hard to say for sure, but it is often ignored and may be the reason why damp is being picked up. When new plaster is applied especailly when a base,backing/bonding application is used and two skims, the walls do take a period to dry out, they do say 6 weeks before you decorate on to these areas. This will sometimes lead to paint blisters.
KB

[Paul B]

Thank you - that would make sense, most areas have dried fine, but there are areas where the wall is less open to the air, and in 'cold'spots of the room and I think it must be a drying time thing - although the paint doesn;t appear to be discoloured or blistering, I do think we should have left them a little longer to dry - I have kept the area well ventilated, and yesterday th eheating went on for the first time and the radiator on that wall is a nice warmth, and the wall felt warmer, less cold, and less 'damp' - so hopefully it is all about the plaster and bonding drying through - may be I wil be lucky and the decorative finish will not be too damaged from haste.

I always wonder if there is any water penetrating from rain, but it seems very unlikley, there definitely was some moisture in that wall which I think should now be pushed out with the new dpc injection...

Luckily it is a small wall, and at the back of the house and all seems a relatively minor problem and more of an irritant than anything else - certainly I don;t think there is any structural risk, it just bugs the heck out of me - difficult being a perfectionist in a Victorian house!!!!

[kbrownie]

The waterproof bonding sand should eradicate water ingress from outside and the DPC should stop rising damp, the only other thing is if your cavity is open further up may be pointing further up external wall and damp bridging across or roofing copings. But give it time and the bad weather will give evidence of any ingress, may just need that little extra time and help to dry out.
KB

[Paul B]

Thank you KB. Maybe I should really stop putting the damp meter onit to check, it is the appearance of the wall that will give me the best indication of a damp problem? Such as blistering paint, or damp patches - would you agee/ There are parts of the wall that do not register any damp reading right next to a bit that registers absolutely none, so it is very patchy - which must be more consistent, I would have thought, of the plaste still drying through.

The bad rain doesn't seem to affect it, although I am sure the area was reviously susceptible to minor condensation, as I say the reading is very surface, I don;t want to pentrate the wall with the meter so as not to damage the finish.

There is no dampness on the floor or the skirting, so there doesn't appear to be a serious damp issue.

As I have said it is a corner area, and low, and a bit dark, so more and more I am hopeful it is just the bonding/plaster still drying through in that area.

Do you think that sounds most likely???

[kbrownie]

I'm sure it is, I have plastered many a wall where the plaster has stayed dark in patches until totally dried. The different depths in the wall adds to this factor and sometimes when the mix is wetter too, plus the factors of the enviromental conditions. I'd just wait for time to take it's course and as the bad weather is not causing any furter problems you should be okay.
KB

[Paul B]

THANK YOU KB.

Are you a DIYer or do you do your plastering and advise as a professional?

Very useful to have someone who knows more baout these things to ask - I live in the SW London area, and if you do this professionally, and if I get concerned I wonder if you woudl look at it for me.

All things taken into account, if there was a significant damp problem I would see it right, I just need to stop using the damp meter I think, it just worries me and could be picking up any measure o moisture, like you say, from the plaster drying to the environmental conditions, to having painted it a little too soon etc.. there is no blistering or bubbling or noticeable 'damp' discolouration of the paint, and the paint has now been on for 3 or so weeks - surely if there was a major damp problem the effects would show signs on the paint by now - and really there is nothing visible, although I do think my plasteriung could have done a smoother job on that particualr part of the wall - hey ho!

[kbrownie]

I used to do a bit, but really pre-concrete, electrics these days and quite good at dry lining too. I live miles away but feel honored you value my opinions and views. I pop on to this website frequently and will always offer help if I can and if not try a point people in the right direction if I know of one! I'm sure that plaster is sound and you may have over reacted regarding damp.
KB

[Paul B]

Thanks KB, I hope I have, I tend to worry more about damp than anything else, even though the area is small, it is not a supporting wall or even a big wall, or even a big decorative part of the house (it is in the back utility and loo).

I think it is the not knowing that worries me, guess I just have to get used to the idea that things can be fixed and the house isn't (famour last words) going to fall down!

I should never have bought a damp meter!!!!!!

P

[kbrownie]

Nothing wrong in wanting things to be right, i'm very much of the same view. She who must be abeyed, goes crazy we me when i'm doing stuff around the house because i'm not happy unless the jobs bob on. Sometimes I think she thinks i'm time wasting and trying to string the job out untill she goes off shopping, then I can put my feet up and watch the footie. I only wish!

[Paul B]

Thanks again KB. So we had a deluge this weekend and I checked the area, no worse no better, no different - so it can only be the residual dampness in the wall from the plastering surely - still indicates two little red dots on my cheap damp meter scattered across the wall in a small-ish area (1 foot square) - but nothing visible, and nothing to indicate anything coming in from all the rain we had over the weekend. The wall always feels really cold around there, even though the radiator is nearby, so maybe a touch of vapour / , moisture in the air settling there too - so frustrating, but maybe I should stop worrying!

The paint doesn;t seem to be flaky, or wet, or bubbling or anything! The woodowrk is not rotting or damp and the floors look fine too! All a mystery really.

The paint used is a bathroom paint, well that was a sheen finish, so perfect for repelling water fom the plaster, but perhaps allowing moisture to condense on its surface more readily, hence the reading.

Any final thoughts?

[kbrownie]

No final thoughts covered about everthing, just let time take is course and hopefully you'll get to christmas happy, I don't put and damp meter on your pressie list!
KB

[Paul B]

THANKS KB - no damp meters on my Xmas list for sure.

It is very hard to distinguish between serious damp and condensation.

For example - had a cupboard build which butts to a wall (that is the inside of the external wall) - inside the cupboard run some warm heating pipes, but that end wall is cold, and no less ventilation means - condensation is forming on that end wall during cold nights when the heat pipes come on in the morinings (I think!) - so now the damp meter is showing some moisture there too - arrrggggghhhh! I think this must be condensation forming on the cold wall surface - so I am going to invest in a mini-de-humidifer and hope that prevents any major build ups of moisture on that wall!

Honestly this damp business can really dirve you mad!

I have read that most damp issues are to do with condensation that any other form of damp, so I am hoping that is true and the mini dehumidifer will draw moisture out of the air in that area.

Now, what do you think of that?