[Misc] Plastering - lime plaster - NSC knowledge request

exKT17 said:

Lime isn't particularly nice to work with but it's fairly straightforward.

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exKT17 said:

The fact is that there is a great shortage of lime pointing specialists and consequently people make ridiculous quotes on the basis that if one mug in 100 takes the bait they'll be laughing. We were quoted £12k to do the exterior of our house (circa 1200 sq ft) but subsequently found a one man band who did it for £6k. So your quote does look on the high side to me.

You could always learn to do it yourself - there are day courses out there. Lime isn't particularly nice to work with but it's fairly straightforward. And you're quite right about needing to use proper lime mortar, not to do so would be a bad idea.

Good luck!

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Seagull on the Hill said:

Lime plastering is very labour intensive.
It usually consists of 3 coats, each of which must be allowed to fully dry before the next coat is applied.
Lime plaster is also more expensive than gypsum based plaster.

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chickens said:

Good morning all,

Looking for advice on plastering an older property. Always believed if the house was built with lime plaster, you should continue to use lime plaster, the risk being damp issues if you use gypsum plaster.

The first room being a 16ft x 12ft bedroom. My first quote was £3100, which was a bit of a shock.

This is the first time a property I’ve lived in has had lime plaster. Is lime plaster that labour intensive by comparison to gypsum?

Edit: I’m not looking for local recommendations as I’m based in South Wales, (thanks @MJsGhost) but what’s a reasonable price for a single room, lime plastering as opposed to gypsum? I know lime plaster takes longer to dry, but I wasn’t aware of other differences that would affect the cost.

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TL;DR Old houses need flexible building materials because they are prone to movement and they need to breathe.

Zeberdi said:

Can’t give you any costs - just the benefit of experience if you are dealing with an old property especially if you have solid walls.

Lime was used in old properties to allow water to penetrate into walls then evaporate again in dry weather/or when fires/woodburners were lit. Old houses were meant to have a movement of water through their solid walls. Preventing that can cause serious and irreparable condensation problems.

The damage DIYers have done to heritage properties over the years is appalling - with cement rendering, gypsum plaster, even trying to inject damp proofing or using interior damp proof linings.

When I bought my property (solid chalk and flint walls built circa. 1730s), it had an horrendous damp problem which only became apparent after I had bought the house (no didn’t have time for a full survey ). The water after a few weeks was literally running down the walls along the entire length of the gable wall. All the neighbours admitted that various previous owners over the decades had battled with damp in the house as far back as they could remember - it had even been delisted by the previous owners because so much damage had been done with ‘improvements’.

Several builders/owners since the 1950s had been patching up walls with all the above methods above and layering plastic paints over plastic based paints. Was advised to dry-line interior walls, repaint with waterproof emulsion and add another layer of paint to gable walls and repair cracks with cement as previous owners.

Knowing a bit about old houses I knew all the damp was condensation caused by previous repairs and ’improvements’, I instead thought bugger the cost, had all the paint stripped off the exterior walls, layered on since the 1950s, exterior concrete rendering removed to first floor level - repaired deep cracks in flint work with reclaimed flints and liquid lime mortar, then lime mortar repairs, followed by lime rendering and 2 layers of ‘sacrificial’ Kilm limewash.

Inside, walls stripped back to gypsum which was removed and replaced with lime plaster, followed by thin layer of chalk based paint, and two coats two layers of the same undiluted.

I also removed all the uPVC windows, replacing them with solid wooden frames set in lime mortar and lowered the ground at the base of the gable wall and removed the concrete slab paving - old houses have no foundations so the base of the wall needs to be higher than the exterior ground.

Yes, all slightly more tricky to apply, especially lime washes (hence slightly higher labour costs) and note optimum weather temperatures are required for exterior lime work. It is also dangerous to inhale, skin burns and can cause serious eye irritation so tradesman need to wear googles.

However, the finish with lime is so much nicer and authentic looking than other plaster finishes. More importantly, lime products are porous and more flexible than cement and plastic products so allow old houses natural movement and to breathe.

House bone dry ever since - that was 6 years ago.

TL;DR Old houses need flexible building materials because they are prone to movement and they need to breathe.

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chickens said:

Thank you all so much for the responses. To answer questions asked so far, the job will involve a new ceiling but only skimming the existing walls.

Based on what you’re telling me, the quote was still too much, but not by the order of magnitude I initially thought. I think I paid £150 per room the last time I did this in 2015, but that was a newer house and gypsum plaster, just skimming all around. I have other quotes incoming, I’ll try and remember to update this with a final price when I’ve got one.

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chickens said:

Thank you all so much for the responses. To answer questions asked so far, the job will involve a new ceiling but only skimming the existing walls.

Based on what you’re telling me, the quote was still too much, but not by the order of magnitude I initially thought. I think I paid £150 per room the last time I did this in 2015, but that was a newer house and gypsum plaster, just skimming all around. I have other quotes incoming, I’ll try and remember to update this with a final price when I’ve got one.

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Seagull on the Hill said:

A couple of questions:
As they are only skimming the walls, is the existing plaster ( I assume it's lime) good (ie when you tap it are there any "hollow" sounds)?
Are they replacing the whole ceiling (ie taking it back to the ceiling joists) or just over boarding what's already there?

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Bodian said:

Dries your hands out terribly.

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chickens said:

Thank you all so much for the responses. To answer questions asked so far, the job will involve a new ceiling but only skimming the existing walls.

Based on what you’re telling me, the quote was still too much, but not by the order of magnitude I initially thought. I think I paid £150 per room the last time I did this in 2015, but that was a newer house and gypsum plaster, just skimming all around. I have other quotes incoming, I’ll try and remember to update this with a final price when I’ve got one.

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Harry Wilson's tackle said:

That TV series presented by Kevin McCloud (Grand Designs) features quite a few houses where the build used lime mortar. It may be worth a trip through the iPlayer if you fancy having a go yourself, just to see what's involved before learning properly how to do it. Best of luck.

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