What can I do with this old plaster?

[Brothernumberone]

Hello. I've recently removed some plaster board from the stairwell to replace a support. I'd assumed there was nothing under the board, but found old plaster underneath. It's straw and mud I think with a skim of hair and plaster over the top. A square of the straw/mud has fallen away, can this be stuck back on? Also the hair/plaster has pulled away from the straw in some places. Is there any way to resecure this?
If not should I cover it all back up again with something?

 

[Roger H]

Hi. I am sure someone with practical personal experience of this will answer soon. I'd not attempt to refix the detached portions. I'd be inclined to check soundness of the lathes, repair if required, and batch up some new plaster to the previous recipe. It looks a fairly rustic finish?

 

[malcolm]

It is tricky to see from the photo where the straw and mud came from. I am reliably informed it is possible to re-use the stuff if you crush it then add a bit more straw and then water. It is also possible to make your own if you need a bit more or buy a repair mix from someone like Ty Mawr.

Is the bit of daub you have from one side of a wattle and daub wall with hazel or something forming the carrier? Most of mine has an improbably thin skim of lime plaster too. It must have worked for several hundred years so might not be a bad system. Where the plaster is loose if might make sense to remove it and reapply. Or just hide the whole lot behind plasterboard so a future owner has something really old to find.

 

[MatthewC]

.... Or just hide the whole lot behind plasterboard so a future owner has something really old to find.

:shock: :shock: :shock:

 

[Brothernumberone]

The bit of straw and mud came from the right side panel where you can see the lath. On the left panel I reckon about 50% of the thin skim painted pink has detached from the straw/mud. I guess I could leave it detached?

 

[livias]

Thinking aloud here ... It looks to ne as if there is a slim ?20mm? panel of daub which used to be attached to laths. And then there is more daub on the other side of the laths. Am I right? Because that is not the usual setup. Laths are used to carry lime plaster whereas daub panels are usually much thicker and built up around a lattice of sticks wedged into the timber frame to make an insulation layer. So your panel is unusually thin and will be unusually flexible so it ix not surprising that it is falling apart. Detective work is called for ... Why do you have such a thin panel? Did the laths once carry lime plaster?

The general strategy with daub is that you crumble up your daub panel, add water and short lengths of new straw to make a nice sticky mess, spray down the backing panel to reduce suction and model the gloop back in place to recreate the panel. But before you start, have a good look at the existing backing panel from both sides if possible because I am concerned that it could fall away if you press on it with new daub. You might be safer to just cover it over as it was before.

The lime plaster panel is presumably sitting on the same sort of daub substrate. If the daub is not moving around then the lime plaster can be consolidated with limewater and lots of patience. I started describing how to do it but decided that words are not the best way to do it. A utube video would be more helpful if you can find one. Or again ... just cover it over again and move onto another job

 

[Brothernumberone]

Thinking aloud here ... It looks to ne as if there is a slim ?20mm? panel of daub which used to be attached to laths. And then there is more daub on the other side of the laths. Am I right? Because that is not the usual setup. Laths are used to carry lime plaster whereas daub panels are usually much thicker and built up around a lattice of sticks wedged into the timber frame to make an insulation layer. So your panel is unusually thin and will be unusually flexible so it ix not surprising that it is falling apart. Detective work is called for ... Why do you have such a thin panel? Did the laths once carry lime plaster?

The general strategy with daub is that you crumble up your daub panel, add water and short lengths of new straw to make a nice sticky mess, spray down the backing panel to reduce suction and model the gloop back in place to recreate the panel. But before you start, have a good look at the existing backing panel from both sides if possible because I am concerned that it could fall away if you press on it with new daub. You might be safer to just cover it over as it was before.

The lime plaster panel is presumably sitting on the same sort of daub substrate. If the daub is not moving around then the lime plaster can be consolidated with limewater and lots of patience. I started describing how to do it but decided that words are not the best way to do it. A utube video would be more helpful if you can find one. Or again ... just cover it over again and move onto another job

Yes, you're spot on. It's a 2cm ish pad of mud and straw pressed into the lath, with a thin (3-4mm skim of hair and plaster over the top. I've held up the bit that dropped off to show where it came from. I think it's a thin wall because it's just intended to seperate the kitchen from the stairwell.
The left side has faired better with the plaster still there, but pulling away from the daub in some places. The right side obviously has no plaster or daub now. The other side of the wall is intact although covered with a horrible 70's style textured paint which can't have helped with breathabilty.