Damp uncovered - cement covering old bricks...

[Hatster]

Hi all,

A while ago I posted about a damp patch in the corner of my dining room, by the blocked up fireplace with additional boxing in. The damp is now identified - I removed the boxing in, and knocked off the cement and polyfilla on the damp patch, and discovered that the cement had been put on top of the original bricks.

The bricks are in pretty good shape, thanks to the lime mortar, I suppose - as I knocked the cement off, the sand literally came pouring out from behind it, but the bricks seem fine, as does a piece of timber that's in there.

I've knocked the bottom foot or so of concrete off the damp patch - the question now is what do we do next? I can take photos if they'll help. The bricks don't look as though they were meant to be exposed at any point, and I'm guessing that the cement render replaced a previous lime render on there.

Thanks!
Hatster

p.s. is there anything more fun on a Saturday morning than knocking failing cement render off a wall to reveal exciting original materials? I offered Mr Hatster a go as I didn't want to hog the fun, but for some reason he doesn't like DIY...

p.p.s. which makes me wonder why he wanted to buy a 17th century house with damp problems...

p.p.p.s. but he is a great cook

 

[Hatster]

Here's the failed cement knocked off, revealing the bricks and timber beneath.

Here's the fireplace as a whole

And the cement from another angle.

What do you think we should do? Remove the cement all along the bottom foot of the fireplace and re-do with lime?

If we do that, can we put lime plaster on top of the existing plaster, or do we need to remove the whole lot? (The remainer is stuck firmly now - it was that one patch that had totally failed)

Thanks!

 

[JoceAndChris]

No doubt someone with far greater experience will post but I'm sure I've read on here that you can patch in with lime, and I've certainly been advised by professionals that I could do that on the exterior here where I've knocked a big hole in the cement render.

Lovely floor, by the way. And lovely green: what is it?

What are your plans for this alcove? Aren't you tempted to reinsate a fire?

p.s. is there anything more fun on a Saturday morning than knocking failing cement render off a wall to reveal exciting original materials?

Hmmm, I preferred your earlier suggestion of the lime-mortar slapping girl on girl action. :wink:

 

[Feltwell]

Hmmm, I preferred your earlier suggestion of the lime-mortar slapping girl on girl action. :wink:

:shock:

Blimey, I missed that one.

It's hard enough finding builders who will work as lime as it is, without insisting that are an all-female pseudo-lesbian lime-mortar slapping building company as well. Now that is a niche market!

 

[FamilyWiggs]

an all-female pseudo-lesbian lime-mortar slapping building company as well. Now that is a niche market!

fnar fnar

 

[Flyfisher]

Now that is a niche market!

. . . or maybe not.

 

[Feltwell]

Thank you, Finbarr Saunders!

 

[Feltwell]

Better do a sensible reply I suppose, before poor Hatster gives up hope completely.....

Highly unlikely that your bricks will ever have been meant to be exposed, that is a modern fashion. They were almost certainly plastered.

Yes, in an ideal world you would remove all nasty modern plasters and have lovely breathable lime plaster everywhere. However, the slightly more pragmatic view that I would subscribe to would be that if it's not broke, why fix it? If you've hacked off the damp areas and the areas above all appear to be dry, then just patch the areas you've exposed with new lime plaster and then put a paint over the top that is breathable and will cover everything - new lime plaster and exisiting gypsum/emulsion. I think some of the clay paints will do this - others have more knowledge on this than myself.

 

[Hatster]

Thanks Feltwell! We do at least try to keep on topic here, although I was going to tell an amusing story of how some lesbian friends of mine felt they would get a bit of eye-candy by hiring a lesbian removal firm...

We had our specialist plasterer yesterday, so we now have some more details

- there were now only approx 7 square ft of lime plaster left in the whole room, and this has modern emulsion on it.
- the vast majority of the room is sand&cement plaster

He said that ideally, if money was no object, we would take all the cement off and re-do the lath and lime plaster. But he felt that wouldn't be the best way to use our budget.

His thinking was that we should hack off the damp areas and then fill and re-skim the whole lot with a modern plaster. In order to prevent damp, he would not take the plaster all the way down to the ground, but would have an inch or so of space between the floor and the modern plaster, which we would then conceal with a bit of skirting.

Basically, he felt that almost the entire downstairs had been re-done in modern plaster at the same time the outside was rendered, and that the thing to do throughout is to have a gap between the modern plaster and the floor.

What do people think to this? It wasn't what I was expecting, but the firm has a lot of experience with listed and timber framed buildings.

 

[Feltwell]

some lesbian friends of mine felt they would get a bit of eye-candy by hiring a lesbian removal firm...

Very handy if you have lesbians that need removing, no doubt!

I don't think much to your plasterer's idea - a inch gap next to the floor covered up with skirting board isn't going to do much to aid breathablity. If he skims the rest with a modern plaster he'll just seal damp in.

Personally, I'd go with the approach that if you have rooms with walls with no sign of damp, leave well alone. If you have areas of visible damp then take the plaster back until you get to dry areas, the re-plaster with a lime plaster, and go over the whole lot with a clay paint which will both allow the lime areas to breathe and cover the modern emulsion elsewhere. Take each wall on a case-by-case example - if you've found that you need to remove 75% of the plaster from a particular wall to get to dry areas, then you may as well take the lot off and avoid the problem of feathering new plaster onto old, i.e. not leaving a visible join.

http://www.earthbornpaints.co.uk/eco-paint-claypaint.php

Just make sure that your damp is not there for other reasons though - such as outside ground level being too high, leaky guttering splashing water on walls, pipe leaks etc.

Did your plasterer actually mention lath & plaster? Have you actually got any walls that are lath & plaster? Your pictures just show brick.

 

[Hatster]

We've got a couple of patches left which are lath and plaster. Most of it seems to be brick or concrete though.

Your advise was much more what I was expecting, Feltwell. Ties in with the SPAB advice as well. I'll see what the next plasterer has to say about it.

Does anyone else have a view? Strong agreement with Feltwell? Strong disagreement?

 

[MdB]

Not an expert but what Feltwell says sounds reasonable. Just make sure you understand the cause of the damp and do what you can to reduce it if at all possible.

 

[JoceAndChris]

Well, without being a plasterer or a damp expert I feel it's churlish to criticize the specialist you got out , but here goes anyway.

The solution he came up with, to leave a gap between his shiny new plaster and the floor, is suggestive that he believes rising damp is the cause of your damp problem, and that by leaving this magic gap, the damp can dry out before it soaks upwards into your wall. Correct me, anyone, if I'm wrong here.

According to the guiding lights of this forum rising damp is often the spectre the damp specialists try to frighten us with, and in actual fact damp problems are usually caused by condensation or other issues. (My damp was blamed on the rising kind, but I think it's far more likely to be a seeping water tank or a broken pipe, combined with condensation and dripping from the roof as the roof has been made wrongly)

You have to really look at all possible causes, and not accept any diagnosis of rising damp too readily until you've ruled out all the others.

I think Feltwell's advice is spot on, and echos what various poor specialist chaps I've dragged round here and given not one penny have said.

 

[DaveBrigg]

Just a note of caution - if the wall becomes damp again, even with lime plaster the clay paint has a tendency to flake, bubble and fall off. We have one wall in our lounge which was lime plastered three years ago, but has damp from sand being behind up to about 18 inches due to a raised floor in the room behind. After several repairs and repaints, the finish coat is starting to fall off the bottom, while the clay paint has flaked to head height. I'm wondering whether I should have limewashed this wall from the start.

 

[Hatster]

Hmmm - thanks very much everyone.

I think what we'll probably do is to hack the cement render off up to a certain height in the damp area and leave it to dry over the summer, and then have it lime plastered up to that height. Then I'll see how well that seems to work and potentially use the same trick over the rest of the house.

 

[rebeccac]

We have the same problem.
I've now taken off all the old 2 inch thick cement render up to the area wher the wall seems quite dry .The floor is like yours but bricks are 300 plus years old laid on a base of lime and stones( original not recent) and at the edge of the room they were wet all along the wall edge. After 2 weeks the damp smell in that room has gone.It looks like you've varnished or sealed yours?
We'll leave the wall exposed until Oct ( we are not living in the house) then replaster that part in lime/sand a weakish lime as they are soft bricks and sandstones.The cement render on the dry wall we are leaving.So far patching up has worked well and I would never now remove perfectly ok plaster just because it was a bit old .Oh and our house has had to survive a strong earthquake and over 2 months of earth tremors! btw its in Italy!