Remove gypsum patching in otherwise good lime walls or not?

[pianoredwood73]

Hi everyone, sorry in advance this is long...

OK, 15thC thatched cob/brick/stone house in Devon. Nastily done in the 1960s-80s.

We've made a start in one bedroom by stripping off the lining paper which covers every internal surface of the house. The vast majority of ceiling and walls are lime plaster which looks sound and very good, better than feared. Ceiling is very billowy in places but looks fab and doesn't appear to be about to fall down despite quite a few cracks...should we be filling these cracks or skimming over with a new coat of lime plaster before limewashing? Is there a way of helping it key better in those areas? Do we just wait and see if it falls down?!! (Got a 3 yr old and new baby due in a few months so obviously can't risk their ceilings collapsing - these also currently have lining paper and are very billowy as well, need advice on that).

Main qu though was: there are a few areas of max one or two m2 which have been patched with cement/gypsum plaster, very hard, mainly around windows (walls are very thick, reveals are therefore the same) and there are cracks where the gypsum meets the lime. Initial thought was hoof it all out and build it up again with lime - however, we think in many of these areas the original lime will come away to a degree, esp on the ceiling around the sloping bit which runs down to the top of the windows.

So should we leave well alone as now 95% of the room can breathe (plan to replace external render with lime as soon as funds permit as well), or go ahead and get rid of all offending material and run the risk of having a fair bit fall off and be lost ie far more work/money but more purist?

Any advice gratefully received. Finally, advice on appropriate finish which won't rub off on clothes? All will need to be applied to every room in the house so we want to get the process right at this stage...

Many thanks if you got this far!
Sarah

 

[skier-hughes]

I had this dilemma, and went the removing route. Very carefully working on the plaster has meant I've kept more than I thought. I have a mix of brick replacements for laths as well which need to come out!!

 

[Andrew Bodenham]

If your gypsum patches aren't too obvious (i.e. are nicely faired in with the surrounding plaster) then I'd leave them. Really, life's too short, and by the sound of things you'll have more than enough to take care of soon. If you start digging out and replacing with lime all you'll be doing is making work for yourself, and if you're lucky it will look just the same when you've finished. So bung a bit of polyfilla or decorators caulk in the cracks and slop on some paint.

A paint expert will be along shortly to advise you.

 

[Nemesis]

Strikes me the reason lining paper was put up was to make some sort of cohesive surface over all on which to decorate. Lime is a much 'softer' texture than gypsum.

If you have a mix of lime and gypsum, and especially if you then have cracks (hard to not have really, gypsum being rather more inflexible than haired lime) then it's going to be complicated to disguise this change totally with paint. It may well keep cracking.

 

[Moo]

That's where some heavy-duty lining paper would come in handy.

 

[Ian Bond]

To fix cracks, I'd carefully scrape the edges to a vee shape and fill with a fine lime plaster. You'd be pleasantly surprised how much of even a ceiling in a relatively poor condition can be saved, given the right methods and enough patience. I've just fixed a ceiling that had been condemned over 10 years ago, and managed to keep 90% of the original plaster.

Getting seamless patches in plaster is extremely difficult - you need to finish the backing coats slightly lower than the existing plaster, so that the final coat will finish level.

Gypsum patches tend to be feathered out over the surrounding plaster surface to avoid obvious joins. However, as you may have found, the modern patches are often done almost perfectly flat, and this jars with the slightly undulating original finish. This is not so much of a problem in a smooth house that was plastered plumb in the first place, but looks horrid in a vernacular building where the plaster follows the uneven contours of the walls. The good news here is that the slight imperfections of your patches actually add to the charm and character of the building. A few coats of limewash or distemper help greatly.

I wouldn't try and hack the gypsum off the laths if it is firmly bonded. It can be done by scoring the plaster in the same direction as the laths and breaking pieces off. But this is very tricky, and you risk breaking the laths. The result of which is a big hole and a bigger mess. Not good.

Limewash would be a perfect finish for your plaster, and if done correctly it will not rub off easily on clothes. Distemper would also be OK, and may be preferable if you don't wish to go to all the trouble and mess of hacking out every last bit of gypsum.

Doing it properly and thoroughly always takes at lot longer than you think, and it certainly makes enough dust and mess. It would be understandable if you wanted to leave off from starting a project of this sort of scale at the moment.

The good thing about lining paper is that it protects the wall surfaces, and you can easily paint it with a modern emulsion. I've seen Farrow&Ball Estate emulsion used to good effect in period properties. It is much easier to strip lining paper off than to try and get modern emulsion off lime plaster at a later date, as I found out to my cost recently.

 

[Penners]

Your cracked ceilings can be effectively repaired in the way that Ian has explained. The only comment I would add is that, if you can get above the ceilings, have a look at the condition of the laths. If they're fairly sound, then the repairs will be well worthwhile. But if they're thoroughly rotten, your crack repairs would really be a waste of time and effort.

 

[Ian Bond]

True, Penners.

Although try not to panic about rotten laths. The only ones I've ever found are where roofs had been leaking for years, and the plaster had crumbled away.

The laths adjoining the water damaged area were perfectly OK. Some nails had rusted, but brass screws and stainless steel penny washers fixed the plaster and laths back well enough.

Hopefully Sarah's ceiling will not be too bad. I've found redoing lath and plaster ceiling hard going, especially all the nailing. And I wasn't even pregnant at the time

 

[skier-hughes]

Gypsum patches tend to be feathered out over the surrounding plaster surface to avoid obvious joins. However, as you may have found, the modern patches are often done almost perfectly flat, a great way for determing where to look to see if it is gypsum or not and this jars with the slightly undulating original finish. This is not so much of a problem in a smooth house that was plastered plumb in the first place, but looks horrid in a vernacular building where the plaster follows the uneven contours of the walls. The good news here is that the slight imperfections of your patches actually add to the charm and character of the building. A few coats of limewash or distemper help greatly.

I wouldn't try and hack the gypsum off the laths if it is firmly bonded. Mine came off nice and easily, normally in great chunks, but it wasn't put on with any great skill, as it wasn't really moulded around the laths, so a little easing and it came away nicely It can be done by scoring the plaster in the same direction as the laths and breaking pieces off. But this is very tricky, and you risk breaking the laths. The result of which is a big hole and a bigger mess. Not good.

Limewash would be a perfect finish for your plaster, and if done correctly it will not rub off easily on clothes. Distemper would also be OK, and may be preferable if you don't wish to go to all the trouble and mess of hacking out every last bit of gypsum.

Doing it properly and thoroughly always takes at lot longer than you think, yes it takes ages...... and it certainly makes enough dust and mess. an absolute enormous amount of dust and mess all around the house, however much you try to contain it. It would be understandable if you wanted to leave off from starting a project of this sort of scale at the moment. I think it may be best to wait unless you are really not bothered by the mess.

The good thing about lining paper is that it protects the wall surfaces, and you can easily paint it with a modern emulsion. I've seen Farrow&Ball Estate emulsion used to good effect in period properties. It is much easier to strip lining paper off than to try and get modern emulsion off lime plaster at a later date, as I found out to my cost recently. I've just scraped off lots of blue emulsion from my remaining lime plaster, boy does it look nice now, but one heck of a tedious job to do it without causing too much damage to the lime plaster.

My thoughts in blue as I've just been doing this, in fact finished getting the emulsion off yesterday, now to start clearing up ready to make more mess

I'll get some pictures for you later, but ave meetings today and tomorrow so may not be until the end of the week.

Graham

 

[Penners]

I wasn't even pregnant at the time

Do we infer that you are now?! :shock:

 

[Ian Bond]

I wasn't even pregnant at the time

Do we infer that you are now?! :shock:

Well, I do eat for two most of the time, Penners. :lol: :lol:

 

[Ian Bond]

I heartily endorse those comments Graham - can't wait to see your latest pics....

I bet even meetings are a welcome break from that paint stripping :wink:

 

[skier-hughes]

Wonder if you can embed a video, let's try, no, doesn't work, will upload to web and post a link

 

[skier-hughes]

here you go.
http://www.myvideoproblems.com/testfiles/personal/kitchen/kitchenhole.htm

 

[MdB]

Wonder if you can embed a video, let's try, no, doesn't work, will upload to web and post a link

BBCode is ON
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[Moo]

That was wonderful, Graham!!!!!!
From now on still photos just won't be enough. We'll need movies with running commentary from (almost) everyone.

ps
Your cat's a real star!

 

[Ian Bond]

Bravo!

That was excellent, and I couldn't stop smiling whilst watching your video. I particularly loved the way your cat managed to steal the show.

Looks like you've had to put some hard graft in there Graham, but it is going to be well worth it by the looks of things.

Moo's right - photos are incredibly useful but movies give that essential extra dimension. It's nearly as good as actually being there - perhaps even better, as we don't have to suffer the dust or help out with the paint scraping.

Ian

 

[skier-hughes]

Ok, next one has the cat scraping off the paint

Which reminds me, I must do the bridge building and then the bridge opening party videos......

 

[Penners]

We'll need movies with running commentary from (almost) everyone

Long may Flash remain off. Sorry Moo, but I shudder at the thought of threads being peppered with people's home movies!

 

[piper]

Sorry Moo, but I shudder at the thought of threads being peppered with people's home movies!

Hear, Hear!