Lime render to combat damp issues. Anyone had it done?

[Quebeccles]

We're trying to find the best way to cure the long-standing damp problems in our 100+-year old brick-built house. Previous owners had it rendered with cement and we understand it’s been that way for many years. Advice is that lime is the best, breathable solution to allow the house to dry out, but obviously it’s a big job to hack off the existing surface and re-render, and would be v expensive.

Has anyone done this and if so, how did it go? Crucially, how much did it cost?!

Not quite the same as you but I have had cement plaster removed and replaced with lime in an area that had damp inside my house. My property is Grade 2 listed, some of it Medieval but some much newer brick.

Had a few weeks of salts almost pouring out of the bricks and then, problem solved, damp gone. Prior to that had been permanently damp, crumbly bricks. Had had numerous suggestions of what needed to be done from building drains to damp courses. All that was needed was replacing the plaster and pointing.

Have now put deposit down for the rest of the cracked cement plaster to go inside my sitting room, will be months of waiting for the builders but can't wait.

Owners of listed buildings can talk for hours about lime plaster and the evils of 'wrong plaster'.

There are alternatives to lime. Some also provide a degree of insulation… or claim to.

bauwer.co.uk/

I did this, external render in lime and two walls downstairs were rendered inside with a supposedly breathable plaster (since been told it was incorrect type). Plasterer had a long history in using lime and has worked on grade 1 listed buildings for the National Trust.

It's been an expensive nightmare. The inside render in parts has blown with horrible damp patches and paint flaking etc. It all needs replacing but I'm not sure what with. I've since had a recommendation that the outside should have been slate hung as it's too exposed for the lime to cope with the water load. Upstairs I think the damp in the walls is forcing the internal plaster (still cement render) off and I guess the joists are getting wet.

I did as much reading and research as I could at the time and everything pointed to lime plastering as being the correct solution. I've since read similar stories about lime plastering internally acting as a poultice to draw water in with people re-rendering after a year. I've also read that line plaster and lime wash were historically used as cheap, sacrificial materials that drew in the salts and were replaced every few years.

My next set of recommendations from an independent surveyor has been for taking the plaster off and replacing with membrane tanking and adding a drain. Builders have suggested the floors should be taken up but there's no guarantee of what they'll find. But I don't have the money and I'm cautious about more failures costing tens of thousands.

Fingers crossed you find something that works for you. I've read many positive stories about lime plaster but wanted to add a cautionary tale. The only wall not damp in my house is the one that is cement rendered internally and externally and had injection damp proof course 20 years ago at the insistence of the bank. Which goes against the received wisdom but its also the most sheltered house wall from wind-driven rain.

@NoToast what a horrible experience, I’m so sorry to hear that 😟 Why are there never straightforward solutions to problems?

I had a quote for replacing cement render with lime - one elevation - ground floor and first and about 7m across not sure how high, anyway, circa £7000

That quote was in the last few months

Thanks @Hardtobelieve123. That’s useful, if scary! Whereabouts roughly in the country are you, if you don’t mind me asking? Was this a specialist/period property company? Just trying to get a handle on whether it’s something any renderer would do - I suspect maybe not.

In the SE. All the quotes seem pretty high but my sister in East Anglia had a similar quote for same size property.

A building company with experience in listed building.

Hacking off concrete render. Might need repointing before re-rendering - and that was not included in quote.

Thanks @Hardtobelieve123

I'm in Ireland so cost will not likely be similar. We took old render off outside of house, repointed the stone with lime, and plastered inside walls of two bedrooms with lime render. Life changing- no damp at all now where there had been everywhere, clothes damp in wardrobe, mould growing behind headboard, damp to touch walls etc.
We got very conflicting advice and subsequently went with other advice in living room, plastered normally with insulated boards. They're damp and pulling off wall and the plaster is cracked.
I'd definitely do lime. Just get someone who knows what they're doing. Our guy worked solely on old building restoration.

Yes we did it too...following a significant leak buried in the then concrete floor laid underneath which seemed to start a chain reaction of damp issues all over the downstairs. We had the walls hacked back to the brick, had the floor dug up to the foundation and replaced with breathable flooring and lime rendered walls. It cost a lot....actual plastering was about 3k without materials around 3 years ago (plasterer was a lucky find and most quotes were 5k and over), it had to be plastered with 3 layers of different lime things and took literally weeks to dry out. It was done as part of other works (we kept finding unrelated things wrong!) so I think prob about 10K easily for that element of it, including getting rid of concrete floor.

However no sign or sight of any damp since and our house is 1760. We used a specialised surveyor experienced with old homes (to argue with loss adjusters who sent in a company initially who made it worse using modern techniques). All good now tho.

I think you need to start by finding the source of the water and correcting it.

Very often it is a leaking pipe or drain.

Also, find the original DPC, and see if it is bridged.

Assumes there is a damp proof course. My house doesn't have one or need one.

No leak but the presence of cement plaster was causing damp to be pulled up from the earth on an internal wall. Once it was replaced by lime, wall went back to breathing properly and no damp.

These houses need to breathe.

Thanks to all for the feedback, much appreciated.

@PigletJohn good to hear from you. We're pretty sure the problem comes down to what AnnaMagnani says. The house is brick and was rendered over in cement at some point which stopped it 'breathing' (we suspect the bricks started to spall and rather than address this, previous owners opted to hide the problem with render).

There were sash windows originally too, but these were replaced by plastic in the past, thus sealing up the house even more. Original fireplaces removed as well, so airflow down chimneys affected. Basically everything was sealed up so it’s all very damp, moist and airtight, which is exactly not how this probably 150+-year old house was meant to work. It feels like a lot to put right!

depending where you live, DPCs will have become compulsory from about 1875

quite likely yours is bridged

the airbricks ventilating the subfloor void may be blocked

iron pipes usually start leaking after about 60 years

clay gullies and drains were mostly cracked around 1940

Thanks for responding @PigletJohn - apparently the drains were actually surveyed and remedial/replacement work done last year (we have full documentation for that). We’ve riddled out all the air bricks but there definitely should be far more than there are.