plaster - to remove or not remove

[sarahj]

Hi there,

Now that its cold outside we are turning to inside restorations, and one of the things I have been considering is the plaster. we have 3' stone and rubble walls that originally were lime plastered, however, now they are covered in thickly painted blown vinyl (probably done when the house was tarted up prior to selling). Under this wallpaper is a gypsum plaster skim over the lime. My question is have I lost the lime plaster forever? Should I try and remove the plaster to get back to the bare walls (the house has a bit of damp around the walls which has anhialated the skirting boards) and then consider limewash/distemper/lime plaster from scratch. Also, I don't know how far the plaster skim extends around or up the walls.

Should I talk to the CO as our house is GII listed although no internal original features exist?

 

[Penners]

If your walls have some damp, it would certainly be beneficial for you to try and get back to lime plaster.

I'm not qualified to tell you whether you'll be able to get the layer of paper and gypsum off the lime, or if you'll have to hack off the whole lot and start again. I'm sure others will reply and advise you on this. Have you had a careful go at trying to lift off the paper and gypsum in a small test area?

I reckon this work could arguably fall under the heading of repairs, which don't need Listed Building Consent. However, it might be best just to give your CO a call and explain what you're planning to do. I'm sure that he/she will be delighted.

 

[Wren]

Hi Sarah

Sounds like you are going to want to rip out some of what is there anyway (once the vinyl wallpaper is all off you are probably left with damaged gypsum anyway). So why not try redoing a smallish area (a wall in one room) using lime plaster and see how you get on with it.

We are beginners so decided to make life easier for ourselves by ordering the lime plaster ready mixed. We ordered the 'how to do it' dvd from Mike Wye and the plaster and tools from Ty Mawr. Carriage costs are a bit of a pain though. This summer we were in Norfolk for a short break and spotted a professional doing some lime plastering and stopped to admire what he was doing. His tip was not to spend to much time trying to figure it out from books but just to get on and have a go.

We are going for those rounded off hand-finished corners which suits a farm labourers cottage. There is one part of the cottage with 'perfect' gypsum plaster (completely flat plasterboard ceiling) and it does look out of place.

Still haven't solved all of the damp problems but in Spring are planning to start work outside on sorting out the drainage (which is a mess), fingers crossed that works.

 

[Gervase]

I've just removed a gypsum skim from two lime-plastered walls, and it wasn't that difficult. Messy and dusty, yes, but with some heavy duty scrapers, it didn't prove that hard. The skim was applied over several layers of limewash and distemper, so there was a natural 'parting layer' which was the first to give under the onslaught from the scraper.
Obviously the plaster underneath was full of holes and crunchy bits (in one earlier repair I found a bit of a farming journal from 1912), but I reckon more than three quarters of it was sound, and the underlying laths were in first-rate nick.
Next step is to patch the areas where I've removed the shagged lime plaster and then skim and brush to get the patches to blend with the old before maybe three coats of limewash, and then no-one will know the wall has been patched.

 

[Penners]

Next step is to patch the areas where I've removed the shagged lime plaster

Ladies and gentlemen,

Our good friend Gervase posts on this forum from Wales. I therefore urge you to forgive any of his prose that may have become misinterpreted in translation.

 

[Geoffrey]

We've just been discovering the construction of our walls as some electrics have been done in two rooms. Sadly it seems all the original plaster has been replaced with a cement based render and gypsum skim.
One whole internal wall is constructed of very hard firecricks on a concrete footing covered with a cement render so hard it took the electrician a whole day to chip in what he thought would take 2 hours.
As you might imagine,right now I'm just over the moon that someone in the 40's/50's decided to care for the building like this!
I can't afford to take the whole lot down and replaster in lime and it hardly seems worth it anyway when the other materials are so unsypathetic. I think all I can plan to do is leave a good gap (even chip away some) between the plaster and the floors so hopefully there can be some evaporation at skirting level which I'll paint with breathable paints.

 

[Penners]

I can't afford to take the whole lot down and replaster in lime

Don't worry, Geoffrey, you're not alone. Our C17th East Anglian timberframe is gypsum on the inside and cement on the outside. The cost of stripping it inside and out and re-covering in lime materials would break us.

 

[Moo]

There are a lot of us in the same boat. We just have to be realistic and do what we can when it's possible and not lose too much sleep about the impossible bits.

 

[Geoffrey]

Thanks Moo and Penners - wasn't meaning to whinge and I know It's not just my house - but good to hear I'm not the only one.
Restored woodblock floor was sanded and Osmoed today and looks great - we've decided to have a rest from moving furniture from room to room and constantly clearing up dust. Once the plasterer has been and the electrician has got the new lights up we can leave everything else for the new year.

 

[stevew]

In theory (I haven't tried it) if you soak the wall the gypsum should eventually turn to mush leaving the lime plaster in one piece (after drying out). I base this theory on the fact that your gypsum stuff tends to hurl its self quite readily off walls and ceilings with the application of a bit of damp. Lath & lime plaster ceilings tend to be able to survive a moderate soaking e.g., leaking water tank etc.

 

[Penners]

I base this theory on the fact that your gypsum stuff tends to hurl its self quite readily off walls and ceilings with the application of a bit of damp.

Sorry, Steve, but you've forgotten the first rule of period properties. Such things only happen when you don't want them to.

 

[NT]

we have 3' stone and rubble walls that originally were lime plastered, however, now they are covered in thickly painted blown vinyl (probably done when the house was tarted up prior to selling). Under this wallpaper is a gypsum plaster skim over the lime. My question is have I lost the lime plaster forever? Should I try and remove the plaster to get back to the bare walls (the house has a bit of damp around the walls which has anhialated the skirting boards) and then consider limewash/distemper/lime plaster from scratch.

Its only really necessary to do this if the wall is damp, or is wood framed and thus at serious risk from damp. Not all bodged up walls will become damp - but some will.


NT

 

[sarahj]

Thank you for all your replys. Penners: yes the downstairs walls have been suffering from damp - we have had the outside repointed and cleared away six inches of ground level. On the downstairs wall there is strange arrangement of stonework at one side of the window - as if it used to be a doorway - as the stones are butted together straight down to the foundations both inside and out. There was a huge damp space here with both damp and cold air. When we remove the plaster here, at least until sill height we will havesignificant repointing work.

Upstairs the very slight damp was coming from the top of the wall downwards (paper coming away from walls) - fixed now I hope as we have replaced the guttering as well as repointed, so reallly we need to see how much needs drying out and how we can help it. we don't have central heating so the house doesn't get very warm upstairs although since we got the wood burning stove instead of the 3 bar electric fire in the sitting room its nowhere near as bad as last winter!

we are on the side of a hill and have quite a lot of moisture travelling through the house, but we don't smell mouldy or damp so I don't think its too much of a problem in most areas.

 

[Gervase]

If you're removing a gypsum skim, take it off dry. You should find that the new parts fairly well from the old with the firm application of a heavy-dury scraper (like this, held at a shallow angle against the wall. When you find a piece that's clearly blown, you can slide the blade of a standard wallpaper stripping knife underneath and pop off a square foot or more (which is very satisfying). I've removed skim up to a quarter of an inch thick using this method.
Wetting the pink thistle skim plaster will just make it hard and wet - the only thing that will turn to mush is old cellulose filler, whch makes a nasty slimy mess that will encourage your scraper to skid across the surface rather than dig in.

Hopefully the new gutting will have fixed the higher damp, but if you find you still have damp in the upper part of the walls you may have to bite the bullet and render or roughcast. Prevailing winds can drive rain hard into the pointing and it will eventually find its way through. Conversely, you make find you can live with a few short-lived patches of damp!

Anyway, it sounds as though you're making good progress.