Author Topic: Solid wall buildings part elebenty - alternatives to lath and plaster  (Read 37108 times)

Mrs Pingu

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No, I am not proposing to get rid of any existing lath & lime plaster wall!

So, back to the saga of my damp gable wall and chimney breast.... when the renovation team come to hack out the cement pointing and replace it with lime, I also asked if they would poke holes in the damp interior walls, remove any debris which might be causing damp bridging and then make it all nice again.

As mentioned previously, I had this wall skimmed in gypsum 12 months ago, (before I became a damp solid wall traditional building bore and realised the error of my ways). I've just spent the last few days scraping said gypsum skim coat off this wall in preparation.

What I have found is that most of the chimney breast is old L&P, but the edge of it, and the sides of the alcove abutting it are not. I assume it's some sort of gypsum plasterboard, but it's not the stuff with a paper surface.

It might help if I post a photo at this point:
2015-12-30_04-52-13 by The Pingus, on Flickr

So you can see on the LHS the problem alcove. The point above the left of the mantelpiece where the 'white' wall stops is the interface between L&P and the other stuff.
If you look at the back of the alcove there is a large stain round where the light fitting is. This has now been stripped of gypsum back to the original lime plaster. And yet creating the alcove itself, strangely is all modern board. This appears to go up as far as a wooden bead I found embedded in the wall about 6 inches below the cornice.
At this point I stopped stripping the skim coat as I figured I might as well get rid of the plasterboard, given then it doesn't breathe.

So my current plan, when the pointing and other exterior works is done and the guy starts work inside, is to suggest they rip out the plasterboard and replace it with something more sympathetic to an old building with solid walls, which is a bit more forgiving to damp.

My initial thought was replace with lath and plaster, but I suspect that will be ££££, so I wondered if there was anything else out there I should consider.
I've been reading some Historic Scotland case studies today where they used calcium silicate board as a hygroscopic, capillary, vapour permeable insulator, but it was basically plastered on the hard (directly onto the stone wall) as insulation with lime plaster affixed to a mesh on top of it.
Given that the problem wall gets a fair bit of prevailing wind and rain i'm not sure that the moisture would go from the inside to the out rather than the other way around!

If you've made it this far, thanks for reading  :thumbsup:
My plan is to paint this wall with claypaint so it's nice and breathable, BTW.

So, any old building owners used alternatives to L&P? I tried Googling but it's mostly people getting rid of L&P, not the other way around ;)
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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #1 on: January 03, 2016, 10:19:07 pm »
Presumably the inglenooks/alcoves are formed within what were existing recesses either side of the chimney breast? If so, I am  bit intruiged as to how could be damp unless there is something else going on apart from external pointing. You could remove the falsework altogether and reinstate the recess/es?
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Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #2 on: January 03, 2016, 10:36:29 pm »
I think that 'new' alcove is a replacement for an old alcove, judging by what I've seen in similar flats for sale on my street. Current suggestions for the damp there are a) from roof, b) from wall, but either way the damp refusing to budge suggests there may be debris bridging between the outer and inner surfaces, not being able to dry out with current cement pointing trapping the water.

Also a possibility is c) water coming down my downstairs neighbours flue. Don't know exactly where that runs, but it must be up there somewhere.

I.e. lots of reasons :(

ETA - I was wondering about wood wool board to replace lath, with lime plaster on top (I assume it would be quicker and therefore cheaper to install than a load of new laths), but not sure how forgiving to moisture it would be.
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Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #3 on: January 04, 2016, 07:35:08 pm »
Lots of new damp patches today :(
Took a look in the attic - water running down the wall, and then soaking into the floorboard which have been butted right up to the wall.
Suppose the next DIY job will be trimming those back if I can manage it. I assume that the big bit of wood lying across the top was only there as a frame for the plasterboard, and it's not going to make anything fall down if I chop it up...  :-\
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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #4 on: January 04, 2016, 07:48:27 pm »
The water is coming from somewhere particularly in the light of your last post. I doubt it is simply rain penetrating a 9" or above solid wall no matter how naff the weather is. Likely suspects are flashings, loose copings, missing dpc, missing or damaged cavity tray where applicable, broken water/waste pipework, leaking gutter or water not going into gutter from roof therefore cascading down into the wall, blocked rainwater pipe or some such. What is the roof detail above this wall?

Is this wall the weathered side? (prevailing wind etc)
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Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #5 on: January 04, 2016, 08:53:44 pm »
There is a chimney on this gable wall. Therefore no guttering or any piping of any sort. There is no dpc.
Probably most likely coming in the chimney from some direction.  It was all supposed be newly cemented etc in the summer but the traditional buildings bloke reckon the slater had done a suboptimal job and the surveyor reckoned the cement around the chimney pots had been covered up rather than replaced so that's all part of the work being done in the spring.
It's not anything I didn't already know about, it just seems to be particularly bad this week.
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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #6 on: January 04, 2016, 08:59:21 pm »
When they do the work pay particular attention to the flashings/soaker to the back gutter (and sides) of the Stack. A sand and cement fillet to the tiles/slates on its own is not good enough and could explain the water running down the wall in the loft. See Lead Sheet Associaion chimney flashing.

Difficult to point you at something without seeing it but the construction of the  midfeathers and gathering in the chimney are also potential problem areas however running water coming into the loft  points to the above sources of ingress.

If you can get the water ingress issue sorted then the subsequent issues can be dealt with accordingly.
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Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #7 on: January 04, 2016, 10:17:17 pm »
Again, I remain at the tender mercies of my tradespeople. This lot seem to have a nationwide rep though and do lots of historic buildings work, so fingers crossed.

So, nobody used wood wool board then?
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Jaded

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #8 on: January 04, 2016, 11:49:15 pm »
All I can add is that the water source needs to be addressed. We've just done that, well, about 5 different water sources*, and now we can start repairing the internal damage.

*
1 - flat roof failure
2 - flashing on stone wall abutting the flat roof loose
3 - frost damage to the stone around this flashing
4 - flashing between original gable wall and new extension pitched roof in the same condition as 2
5 - frost damage to the stone around this flashing
6 - incompetent formation of lead in gully: 12 foot length beginning to fail
7 - incompetent formation of lead in gully: split in joint almost certainly created when the lead was put down
8 - some other things

OK  - so more than 5 but lots of different things. The first 5 resulted in water coming in in the same place.

Canardly speaks sense. Particularly about the risk of cement instead of lead. Are you able to stand back from the chimney (e.g. with binoculars in a neighbours) to see if there is a gap between the cement and the chimney?
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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #9 on: January 05, 2016, 06:54:27 am »
Again, I remain at the tender mercies of my tradespeople. This lot seem to have a nationwide rep though and do lots of historic buildings work, so fingers crossed.

So, nobody used wood wool board then?


If I employed a builder I would expect them to offer me advice on what needed doing; have these people no opinion?

My barn had a damp wall that only came to light when I pierced it for windows.  It was a rain-facing wall so first off I repointed it.  It looked a lot nicer after but was just as wet. 

After much thought I realised the water was being blown in under the tiles.   It is amazing how much water wind can move horizontally!  After fitting deeper edge flashings the wall started to dry out.  It'll take a year or two before it is completely dry being 70-80cm thick.
Sic transit and all that..

Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #10 on: January 05, 2016, 07:43:40 am »
After much thought I realised the water was being blown in under the tiles.   It is amazing how much water wind can move horizontally!  After fitting deeper edge flashings the wall started to dry out.  It'll take a year or two before it is completely dry being 70-80cm thick.

As its a gable end, this is a likleyhood, as the tiles will just cap the wall - there may be no other weartherproofing (no barge boards/sifits) along that end (our 1840's cottage doesn't, I can't remember what Aberdeen tenements have on the gables)
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Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #11 on: January 05, 2016, 03:21:06 pm »
We have a skew at the end - see pic here (the first of the 7 images is similar) : https://www.scotlandschurchestrust.org.uk/maintain-your-church/glossary/?term=250

The cement filet which is supposed to cover up between the edge of the slates and the skew was replaced last summer. That obviously made a lot of difference, not.
The people coming to do the pointing say that the cement filet was done incorrectly as there is supposed to be an overhang at the top of the skew and the filet (guess will be lime next) is supposed to be tucked under this lip to stop rain getting in behind it, and that the previous slater did not do this but just covered up the lip. I can't see any evidence of this lip from the ground so I don't know. They also suggested that the cement joins between the blocks making up the skew need scraping out and repointing which I suspect wasn't done by the slater last year.
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Aunt Maud

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #12 on: January 05, 2016, 04:52:17 pm »
Are they really re-pointing the wall at the moment ?

Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #13 on: January 05, 2016, 05:08:30 pm »
We have a skew at the end - see pic here (the first of the 7 images is similar) : https://www.scotlandschurchestrust.org.uk/maintain-your-church/glossary/?term=250

The cement filet which is supposed to cover up between the edge of the slates and the skew was replaced last summer. That obviously made a lot of difference, not.
The people coming to do the pointing say that the cement filet was done incorrectly as there is supposed to be an overhang at the top of the skew and the filet (guess will be lime next) is supposed to be tucked under this lip to stop rain getting in behind it, and that the previous slater did not do this but just covered up the lip. I can't see any evidence of this lip from the ground so I don't know. They also suggested that the cement joins between the blocks making up the skew need scraping out and repointing which I suspect wasn't done by the slater last year.

I'd a join like that where my hangar meets the barn wall.  It was a problem area for many reasons and water incursion had damaged the barn wall quite badly, largely due to the meltwater from snow that piled up there.  In France you can buy profiles that consist of zinc with a lead strip along the edge.  The lead is tucked into a convenient join (the sloping gable head, maybe) and the zinc fastened to the vertical wall.  This gives a watertight base over which the mortar fillet can be added.  The zinc profile is designed to hold the fillet in place. It's then an invisible modern fix and very effective.  I did the work about 7 years ago after re-roofing the hangar and repairing the damaged barn wall. 

Whilst it is nice to fix old building without more modern methods being used, the problem is that damp may well be one of the original features you retain!

Sic transit and all that..

Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #14 on: January 05, 2016, 06:28:00 pm »
Are they really re-pointing the wall at the moment ?

No. Spring.

Meanwhile I've got tons more wet patches this week, probably something to do with a slate lying on the ground outside.  Shall see if I can get hold of the tame roof monkey to poke something back together in the meantime....

Great time for the dehumidifier to decide that it isn't!
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Aunt Maud

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #15 on: January 05, 2016, 07:04:05 pm »
You need to get that roof fixed asap and stop the rain getting in as best you can.

Glad to hear that they aren't re-pointing till it warms up.

Lath and plaster is really easy to do, there's really nothing specialised about it at all, but finding someone to actually do it without making a song and dance about it might be another matter.

Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #16 on: January 05, 2016, 08:22:40 pm »
Are they really re-pointing the wall at the moment ?

No. Spring.

Meanwhile I've got tons more wet patches this week, probably something to do with a slate lying on the ground outside.  Shall see if I can get hold of the tame roof monkey to poke something back together in the meantime....

Great time for the dehumidifier to decide that it isn't!


Do they know that is what you think of them?   Therein could lie the answer to your difficulties ;)
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Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #17 on: January 05, 2016, 09:02:29 pm »
:P That's actually the 4th slater I've had, though he didn't have anything to do with the cement fillet which has apparently to come out. I've just been using him for a few weeks jobs since then.
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Mrs Pingu

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Re: Solid wall buildings part elebenty - updated and more oddities
« Reply #18 on: March 22, 2016, 09:23:59 pm »
So, the pointing and other external works are just about finished. No doubt it's going to take the wall some time to dry out. Moving back to the internal walls...
There was a bit of miscommunication between the trad building bloke and me so it's not started yet as he's requoting. I decided to do some more archaeology which led me to this:
Living room archaeology by The Pingus, on Flickr

So you can see I've started ripping the crappy alcove down. Looks like the original l&p walls are still there, so why bother putting the alcove back up, it just eats space.

Next question though, what on earth is the structure above the beading? It seems fairly solid, though quite damp. Don't understand why there would be this big chunk of stuff sticking out of the wall right under the ceiling.

Living room archaeology by The Pingus, on Flickr

This is looking inside the top of the alcove,  the damp paper is hanging off the bottom of this structure.
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Aunt Maud

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #19 on: March 23, 2016, 07:55:42 am »
What's "the thing" made of ?



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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #20 on: March 23, 2016, 08:07:10 am »
Careful. That looks a bit like a builders bodge I discovered in our place. Check the joists and floor above at the wall - are they sound? Or, is there rot at the wall in the joists? Are these blocks to hold up the ceiling? Which have been hidden in the falsework arch? That is what had been done in my place to disguise rotted out joist ends.
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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #21 on: March 23, 2016, 04:53:46 pm »
Surely the alcove used to be a press? (cupboard in the thickness of the wall for those not familiar with Scottish traditional properties).

As such it would have quite possibly been lined with tongue and groove softwood panelling rather than plastered. It would have stopped short of the ceiling because there was a door on the front with a frame round it.

(+1 that the water's probably coming from botched repair to skews and raggles where roof meets gable wall, or haunching where chimney pot meets stack, or failed flashing where chimney stack meets slate)

Aunt Maud

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #22 on: March 23, 2016, 05:31:06 pm »
That makes sense.

The bead looks the same as the bead on the curved recess on the right of the fireplace.

Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #23 on: March 23, 2016, 05:45:59 pm »
The bead does look similar, but it's very clean so I suspect it is new and on top of the old wallpaper there.  There are also no softwood panels back there.

I'm not sure what the 'thing' is made of, I don't think it's wood but I didn't have a right good feel and I've put the ladder away now. Once the weather goes crap again I'll take the rest of it down and look again.
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Mrs Pingu

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Re: Solid wall buildings part elebenty - alternatives to lath and plaster
« Reply #24 on: March 23, 2016, 06:46:09 pm »
OK, I've been on tippee toes and yanked some damp paper off (note to self, scrub plaster with sugar soap). It looks like more lime plaster on the underside of the structure there (it's got lovely pink mould on it, yum), so if it's a builders bodge then it's an old one. I gave it a tap but didn't glean anything new. There's a bit of plaster coming off the front corner so I might have a tentative look behind that when I get up on the ladder.
If it is just more l&p up there I I imagine the laths are rotten.
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