Damp Proof Damp

[MisterFish]

Hi

Sometime ago I discovered damp on my front room chimney breast. I assumed it came from an uncapped chimney, (I had previously removed a gas fire from the fireplace). Last summer I capped the chimney and checked the stack, roof and flashings for damage – there was none. I then left the room until this year to dry.

When I raked out and filled the area recently I noticed that the filler wouldn’t dry.

I called in a damp expert. He diagnosed rising damp and prescribed the following:

1. Remove plaster from the lower part of chimney breast
2. Inject DPC
3. Replace plaster with waterproofing formula.

This work was carried out last week (Thursday). I asked the guy how long the work would take to dry and was told that it should be dry in a day or two, by Monday (today) at the latest.

The work has not dried, this was it this morning.

In addition I am seeing a strong salt line appearing at the edge of the work, and rust is blooming through the edge where he replaced the beading, see here.

Is this normal or should I get the guy back?

If it is normal, how long might this really take to dry, (I have to paint before the floor coverings can go in and that is booked for next Saturday, do I need to cancel?

Thanks for your help guys.

M

 

[Micilin]

If he 'replaced' the beading ie used plastering beads fixed to the wall before the float coat then it is a bodge job. Needs to be taken off and done properly. Did you get a spec? What additive was used in the mix? It even looks shoddy. This needs redoing. Get them in and get us the info above to help you make your case.

 

[TheVictorian]

That looks significantly wrong to me.

Have you looked under the floorboard to see what state the subfloor is in? I'm always more interested in stopping the problem at its source (burst pipe, water ingress from standing water at the other side of the wall etc), than hiding the problem.

I had a similar issue with my chimney breast and the problem was caused by the path at the side of my house sloping towards the house rather than away from it.

 

[JohnD]

A disused chimney should be ventilated top and bottom, not sealed shut like yours. Hiwever yours is so very wet at the bottom that I suspect a leak. Was there ever a back boiler?

I think you need to open it up and look inside.

You have wasted your money on that "damp specialist"

If you invite someone into your home who sells damp treatment you can expect him to tell you to buy damp treatment. Don't give him any more of your money.

 

[MisterFish]

Hi Micilin

I've given them a bell and am waiting for a call back to get them back in for their opinion.

In answer to your questions, AFAIK:

The outside of the chimney breast was, prior to this, beaded around with a plastic bead and plastered to that. He cut the bead to the level of the plaster removed and replaced that section with a metal bead after applying the first (presumably damp barrier) coat of plaster and before the surface plaster.

You will have guessed by now that plastering is not my strong suite but the two layers (and the injection) can be seen here.

In terms of spec that I got, the one I gave in my previous post was it. i.e. :

1. Remove plaster from the lower part of chimney breast
2. Inject DPC
3. Replace plaster with waterproofing formula.

Incidentally I had two quotes and, spec wise, that is pretty much what they both said. I assumed that was normal.

Additive used? - no clue, will ask when he gets back to me.

P.S. He just called me: The additive was "a salt nutraliser", he can't remember what it is called. He also says that the salt line is just what happens when new and old plasters meet, the rust is nothing and will wipe away when the thing dries, and that the job will dry happily in the next few days.

Cheers
M

 

[MisterFish]

Hi The Victorian

The subfloor is the cellar, which is dry.

There is a path on the outside of the wall, there is no standing water there but I take your point. It would seem very strange to me if damp was penetrating the wall ONLY at the chimney (which is, of course the thickest part of the wall) and not at any other place.

M

 

[MisterFish]

Hi John D

This disused chimney IS vented top and bottom (bottom venting can be seen in the photograph in the original post).

I have opened it up an looked inside ... I did so when I took out the gas fire. No, there was never a back boiler, it was a little damp at the time so I capped the chimney and waited nine months, (see original post). (The fireplace was closed off with insulated board BTW)

If you don't ask a damp specialist about damp it is kinda hard to imaging where the help might come from. That sounds a little like not calling in a plumber to a difficult leak because they might recommend plumbing work.

Who would you suggest I should have asked?

 

[TheVictorian]

Hi The Victorian

The subfloor is the cellar, which is dry.

There is a path on the outside of the wall, there is no standing water there but I take your point. It would seem very strange to me if damp was penetrating the wall ONLY at the chimney (which is, of course the thickest part of the wall) and not at any other place.

M

In my case, damp rose up the chimney because the pillars did not have a slate DPC, where as the wall behind them did. This could be exactly what you are experiencing. It took months for mine to dry fully after the path was adjusted, I also had a couple of rotten joists where they had been in contact with the damp brickwork.

 

[Micilin]

Mr F - Get the spec for item 3 ( application method, materials) and and find out the name of the additives used. Can't remember what it was called ? Really poor , this man is a cowboy. If he is lying, he is a cowboy, if he is telling the truth, he is a cowboy

My first reaction to someone saying that the rust is 'nothing' is that they not only don't know what they are doing, but assume that you are stupid. Now that seems harsh but is that bead what you want in your room? Are you going to paint over a rusty bead? Even if you remove the rust you can see , what about the metal underneath the finish? If the rust is 'nothing', Will it really go away?

Did he use washed salt free sand? Don't give him that detail until he tells you what kind of sand he used, or else the ansewr will just be yes. Ask him where he got the sand as the you can ask the supplier.When I was at this game I used to get a cert to say my sand was 'washed salt free fine sharp' to BS1199 (We were BS audited by spot check)

Chop the bottom of where the bead is, under your skirting line and show or tell me if it has a 2" mesh or is a thin coat bead.

The correct way to do this work is render first so the whole area is sealed and then have a thin coat bead put on over this, not a plastering bead that allows damp to track thru the render from the wall.

I suspect that he used plaster to dab the beads on but you need to help me by doing the above.

Find out the additive. If he can't tell you ask for the receipts for the material.

This has to be redone and done properly. How much have you paid him?

PM me if you don't wish to disclose anything but you can't leave this job as it is

 

[MisterFish]

Hi Micilin

I have emailed him asking for the spec, more on that when I get it.

The bead, I think, is a thin coat one. As I said plastering is really not my thing. The bead can be seen here

The correct way to do this work is render first so the whole area is sealed and then have a thin coat bead put on over this, not a plastering bead that allows damp to track thru the render from the wall.

To be fair, this does sound like a reasonable description of what I saw him do. (assuming I am interpreting your words and my observations of his actions correctly, remember, Plastering is really not my ......)

The cost of the job was £220 and took him slightly less that half a day.

More when I get it.

M

 

[MisterFish]

Hi TheVictorian

The 3 foot wide path outside is dead level and dry, ('cept when it's raining). The other side of the path is my next door neigbours wall so sloping it away from my house and into his might not make me terribly popular.

There is an injected DPC running the length of the wall that turns upwards at each side of each chimney, (there are two stacks, one front and one back, along the wall). The other chimney stack on this wall, and one other further around the house have shown no signs of damp

The two guys that came, (sepeately), to quote both said that that the problem stemmed from the DPC not having been injected far enough into the wall at that point to accomodate the extra depth of the chimney stack.

I don't know enough to know whther they are right.

 

[TheVictorian]

Your house should not have a damp problem even without a DPC being injected and probably worked fine for 100 years. Something has changed to make the damp a problem, injecting it just holds it back (sometimes) and does not fix the problem at its source.

 

[Micilin]

The other posts on the cause are important to note.

I'll carry on with the plastering side of it

Ok, it is good that he has used thin coat beads if he has rendered behind them as this eliminate that.

(However, his plastering should not be touching the floor anywhere)

This probably leads us to the material used - sand quality and additive which we need to wait for.

Regardless, there is no way the bead should be rusty or left rusty

 

[JohnD]

can you see the chimney breast in the cellar, and does it seem dry?

If you draw a pencil line round the wet patch, and pencil the date on it, you wil be able to see if/how fast it is drying out.

The metal bead (unless you use stainless, which is better) is galvanised, so in the absence of salt it should not go rusty that fast, especially indoors.

incidentally, when you are lucky enough to have a cellar, you can often cut a ventilation hole into the flue from there, so it does not show in the room, and helps ventilate the cellar too.

 

[MisterFish]

Hi TheVictorian

Your house should not have a damp problem even without a DPC being injected and probably worked fine for 100 years. Something has changed to make the damp a problem, injecting it just holds it back (sometimes) and does not fix the problem at its source.

I entirely agree and take your point. I am not sure where to go with it though.

The path is level, there is a dry cellar underneath, (lifting the floorboards reveals the dry cellar ceiling). It maybe that the cellar is somehow waterproofed and the damp is coming from something outside of that that I cannot see or access without tearing out the cellar.

There is a very high water table here, (even without the last 12 months of decidedly un-mediterranean weather). The garden is about 12 inches lower than the lowest part of the house and digging down less than two spade depths from there gets you below the water table. Short of demolishing most of an urban area that wasn't here 100 years ago when the house was built, and planting trees, that isn't going to change.

There almost certainly is a cause, natural or otherwise but there is a limit to the amount of destruction that it is feasable to undertake to find it. Hence the DPC workaround.

M