Lime plaster on a wattle & daub ceiling

[CarolineTheChemist]

Does anyone have any experience with lime plastering a daub ceiling? We currently have lime plaster on the ceiling, but it has detached in places and in others has been repaired really badly, so I'm thinking to take it off and have it put back.
A few professionals we've spoken to think it's very difficult, but I'm feeling positive! Please tell me someone has had it done successfully?

The other ceilings have already been replaced with plasterboard and it's just no where near as beautiful.

 

[Flyfisher]

I’ve not come across a daub ceiling in our C16 house, they are mostly laths, though we have plenty of wattle & daub walls. A daub ceiling probably provides quite good insulation though.

We’ve had some areas of daub walls lime plastered and the plasterer had no problems with adherence, he just seemed to ensure the daub was fairly wet beforehand to prevent it sucking out all the moisture from the plaster. I suppose that judging that sort of thing is part of the skill set required.

I often think when a tradesman says something is difficult it means they’ve never done it before or they simply don’t want to do it. Finding another tradesman might be the answer, though I know from experience that’s easier said than done in many cases.

 

[TheForge]

Quite rare to find a genuine wattle and daub ceiling intact, daub was normally applied to both sides of the wattle simultaneously to give the partition its strength and would be difficult on a horizontal surface.

Are you sure it’s not a lath and plaster ceiling with the finish/setting coat delaminating from an earthy base coat?

Do you have any pictures?

 

[CarolineTheChemist]

I'm pretty sure it's daub. In the attic room above I've taken up some floor boards (found a shilling from 1816 under there!) and found it's lovely smooth strawy daub on that side too. Clearly it shrank quite a lot as around the edges somone has filled in a couple of inches with something hard, grey and cementy looking. You can see it quite clearly from the ceiling side too. We live in an area with very heavy clay soil so it makes sense that they used it in abundance.

I was trying to add some photos to my first post, but couldn't figure out how. Do I need to host them elsewhere first?

 

[CarolineTheChemist]

I've taken a few photos (sorry about the quality!) from the plastered ceiling side showing some of the plaster damage, and some from under the floorboards in the room above.
Those show that the daub was applied to the ceiling wattles from both sides between the floor joists.
https://imgur.com/gallery/QdDuh4S

 

[TheForge]

Blimey that’s interesting and looks to have been well applied originally. What date is the house and is it listed?

It looks like there’s some staining on the ceiling around the delamination which might indicate water damage has caused the top coat to fail.

I would carefully cut back the loose material that has delaminated, assess what it is, composition, number of coats etc, possibly have it analysed professionally if unsure, and then reapply a patch repair to the delaminated areas only using a suitably lime rich, ‘sticky’ non hydraulic setting plaster. This will preserve as much of the historical fabric as possible and keep costs down. A competent lime plaster specialist should be able to do this and feather the joins.

I would also look at what paint has been used, it should be an appropriately permeable paint (distemper or limewash, or the modern fad for clay paint). The flaking might suggest a less permeable modern emulsion has been used which ideally should be removed if it can be done without further damage.

 

[CarolineTheChemist]

Thanks for the help TheForge! Much appreciated! The ceiling is in our main bedroom so I often look up at night and wonder what on earth we're going to do about it.
The house is late 17th Century and grade II listed. The daub all over the house is in a much better state than the lime plaster that covers it. It's very sound in almost all places, although there are a few spots where wasps have made nests between the daub and the tiles and there we will need to do some repairs.

https://imgur.com/a/SsbezfS

We did a wattle and daub course at the Weald & Download Museum over the summer, so will probably give repairing ourselves it a stab at some point. Sadly over the years it has often been taken off and plasterboarded over. I often find big loose chunks of daub under the floor boards, in the attic or under a cupboard near the plasterboarded walls. I'm collecting them all so we can re-use them in the repair.

There are lots of stained spots like that one on the ceiling. We think it's from yellowing PVA glue that was used to stick down the flaky bits of paint; in some patches you can see the brush strokes in the glue. I'm also pretty sure it has been painted in modern emulsion too, but seeing as it has been there a long time, I guess it's possible that there's distemper or lime wash underneath. I've taken a few more photos so you can see the extent of the mess and the flaking. The first photo shows a part that has been repaired with something hard and smooth, so probably no daub or lime there anymore. Do you think it's possible to scrape off the emulsion and preserve the lime plaster? The ceiling is about 4m x 5m wide.

https://imgur.com/lyihJew
https://imgur.com/JeVGhS1
https://imgur.com/4TNzUNH

 

[TheForge]

It looks like the paint, what ever it is, would come away readily but you’d need to try a small area in an inconspicuous spot to gauge.

I’d be reluctant to introduce too much water given the nature of the base coat but a damp sponge may help.

The picture of the wasp nest looks to show laths rather than wattle.

I’d suggest you need to consider why the areas of delamination have failed before attempting a repair. If water damage isn’t a factor then it may be that the base coat is too smooth to provide a good mechanical key.

It will be important to control suction by the base coat on any attempted repair by suitable dampening of the daub/pricking up coat. It may also be necessary to create texture to promote a key but a fine balance will be required to not disturb more historic fabric.

 

[malcolm]

What a wonderful ceiling. I've got one a bit like that (from 17C probably) in a room that somehow managed to be ignored while the rest of the house was being messed around again and again over the centuries. Mine has a muddy straw construction which has survived really well. It's a funny shape now. The plaster finish is lime and it just needed some cracks filling.

From the photos it does look like you mostly have sound plaster just with a really badly failed paint finish. I would remove the plaster where it has fallen off and patch up with lime (it will work fine so long as the clay is wet. Clay will take a lot of wetting maybe over a day or two before it is wet enough for plastering). This is stuff you can do yourself with a bit of advice from this forum. Most times that is a more sympathetic approach than getting builders in.

It's a real hassle removing modern paint that has been applied directly over old plaster. Back in the day they would have put lining paper on the plaster and painted over that. That would have been easy to strip and would have taken the modern cracky paint nasties off with it ready for new paper and a new finish.

Worth trying the best you can to remove the flaky paint. If there are lumps you can't remove then maybe smooth them off with a bit of filler and put lining paper on top. Lining paper covers a lot of sins while preserving your most wonderful ceiling. Paint over the lining paper at will using breathable paints if possible rather than the emulsion that caused the problems.

 

[CarolineTheChemist]

Thanks to you both! Malcolm that's interesting what you say about going DIY being a more sympathetic approach than getting the builders in. My husband and I are already starting to think that way... I guess money can't always buy something that needs to be a labour of love!