We have just bought an Cornish old granite barn which has cement pointing outside, cement render inside & would like to make it drier inside. There is both penetrating damp & condensation.
I assume that the best way to get there is to try & manage the moisture rather than block it, not least as there is no damp course. Lime seems to be the only real option to do this, but at some cost!!!!!!
In order to stop the penetrating damp it has been suggested we repoint & waterproof the building with a breathable covering. Internal wall insulation will hopefully help with the condensation.
We have been quoted 70/m2 for the repointing (& painting with an ‘active’ breathable system like beeks) & it looks like 40/m2 (plus hacking off & disposing of the old render) for internal fibreboard insulation & lime plastering. If we do this it will have to be in 2 stages due to cost – repointing 1st, then the internal work.
Has anyone had any experience of doing this? If so did it work? Do these costs seem reasonable? Are there any other sensible options?

Am not certain of the m2 costs, but I’m typing this from within an old outhouse – c. 1880/1890 – which was a ruin when we moved in. We bit the bullet and renovated it — re-roofed, new windows, unpicked existing mortar and re-pointed with lime.

Inside it’s full-on Kingspan insulation, floor insulated as well as some in the roofspace. I only work in it – not live – and very little generators of condensation, but other than a rubbish slate/Velux interface, I’ve never had damp issues.

Didn’t get the outside coated or treated in any way though..

Guys up this way are pretty tuned in to working with lime these days, there’s a lot of historical buildings getting the treatment, and there’s even a raft of apprentices being trained locally by Historic Scotland.

Typical material here is sandstone which really doesn’t like being pointed with cement mortar – hence the emphasis on getting it done right with lime..

Lime is certainly the way to go! Both the cement pointing and internal rendering are not letting the wall’s breathe and are doing everything to retain the inherent moisture.

Without seeing it specifically, I would suggest going for the re-pointing with hydraulic lime mortar on the outside, using NHL 5 from ground level to about 1 to 1.5 metres and then use NHL 3.5 above that. I would also suggest getting all of the internal cement render of the internal sides of the walls and again, repoint with the same hydraulic lime.

Please do not paint! IME the only breathable ‘paint’ is lime wash, but let the walls settle for a year or so after you have done the repointing before even considering any other covering.

People who paint their properties need to be fined IMO, about the worst thing anyone can do to a brick, stone property!

Get in touch with the Lime Centre near Winchester. Very knowledgable, friendly and good advice

The Lime Centre

Oh, and please. Do your new property a favour and get the cement out of it and do not paint it!! 🙂

@kcal

Whereabouts are you? We moved into an old place in the borders at the end of last year, and whilst I’ll be doing some of the re-pointing myself, there’s some work that’s a bit beyond me, is there anyone you recommend? Also, if you know any good suppliers of lime it’d be appreciated, ta.

Historic Scotland do a lot on this and publish papers and advice notes:

http://conservation.historic-scotland.gov.uk/home/publications.htm?callback=1&searchterm=lime&system.customproperties.pt9=on&submit=Search

@honeybadgerx — sadly we’re in NE Scotland – Moray specifically – so I really don’t know anyone down Borders way.

There are two companies here – http://www.masonryandlime.co.uk/ (who seem to be NE specific) and LTM (http://www.traditionalmasonry.co.uk/index.aspx) who reach as far as Stirling / Kirkcaldy.

I’m sure there are similar offshoots in Borders and definitely in Edinburgh – there were HS guys onsite at Rosslyn Chapel for years, I’m sure many of them have gone freelance since.

I know a friendly architect from days gone past in Edinburgh, he might have some pointers, and a couple of contacts in Peebles who may be able to help?

That’d be much appreciated, we’re maybe looking at getting an extension done in the next year or so, email is jasgeo84 at the google one, if you don’t mind firing some stuff through.

+1 what slackalice said

I’ve done a few barn conversions in the past, the key is getting it repointed well in lime by someone experienced in the material (I see so much terrible repointing as a surveyor).
Had a very successful job with lining walls with gypoc frame system, either independant or onto rails fixed to the walls, then gyproc thermal board and plaster skim over. The thermal board is a kingspan like closed cell insulation with a plasterboard face.

Cement generally does more harm than good in stonework. Steer well clear of breathable paint bollocks too, all you’ll do is limit the breath-ability of the stone and trap moisture.

Jeff

Thanks for the info so far. It looks like I’ll have to bite the bullet – anyone have any indication of a decent price/ m2?
The painting suggestion is because we are on a hill – think of water being fired at the house at over 30mph (& up to 99mph!!!) for most days in the last 2 months.

Granite can be an absolute nightmare to weatherproof particularly if you have narrow joints which draw water through by capillary action. What is the nature of the stonework (if it is rubble it may need to be re-rendered (We get lots of problems with people revealing the original stonework which was never intended to be exposed and then wondering why water is getting through))?

Lime is the best for re-pointing, rendering and plastering unless you are in a seriously exposed location NHL 3.5 should be suitable for everything. Most of the problems with the material are due to people trying to use it as a cement replacement so it is best to use someone experienced in the material. You should also allow for protecting and tending the curing mortar/render as it is far more sensitive to conditions than cement.

Lime Plaster generally looks great unpainted but if your after something special Ty Mawr ‘Glaster’ has pulverised glass in which gives a slight sparkle to the finish.

The traditional external paint for lime render is Tallow bound limewash. It can be made on site but is best done by a specialist

Avoid the painting. Lime and stone make perfectly good walls and have stood for a very long time all over the world. The painting sounds like someone who doesn’t understand lime very well. I’m lucky enough to have met and been lectured by Stafford Holmes, a world authority on lime in building. His book is a good reference point, as are a few of these:
http://www.buildinglimesforum.org.uk/lime-publications

There are a lot of good people working with lime – you just need to dig around in the restoration and green building worlds to find them.

No doubt being on hill exposed to the prevailing SW does mean that rain comes in horizontally, however, if the lime pointing is done correctly by someone who knows how to do it with the local stone, any water penetration will more quickly be released if there is no paint in which it can and will get trapped behind. Lime mortar pointing is pretty hard and resillient stuff when left to do what it does best, without any modern shite spread all over it.

Furthermore, the last 2 months weather have been rather exceptional.

I wouldn’t give any sort of price indication without a site visit personally. Too many variable factors involved. Find some recommended local experts, maybe search for a local lime supplier, they may have a list of people they regularly supply.

As you know, this is the structure of your building, the pointing is integral to it’s longevity and security, spend your money wisely on this and you’ll be fine.

@kcal

Whereabouts are you? We moved into an old place in the borders at the end of last year, and whilst I’ll be doing some of the re-pointing myself, there’s some work that’s a bit beyond me, is there anyone you recommend? Also, if you know any good suppliers of lime it’d be appreciated, ta.
honeybadgerx

In a very similar situation to you. 200 year old stone house, concrete pointing, condensation everywhere. The whole lot is going to need doing, but for some reason I’m quite looking forward to it.

The bloke we used to survey our house, called Darren McLean. Website is here: Timber & Lime. Very knowledgeable, nice to chat to, knows his stuff and how to explain it to the layman. Based somewhere south of Glasgow. He does work himself, but is also willing to train you 1-2-1 so you can do it. Highly recommended.

For buying your lime mortar he recommends Masons Mortar, as do I. They’re pretty cheap too, at least cheaper than I was expecting. Cost about £25 for a 25kg bag of pre-mixed NHL3.5, which should do the interior of the gable end, at least. They also do course on repointing which are cheaper than Darren, but are also recommended by Darren.

OP, try talking to the people at the Cornish Lime Company (http://www.cornishlime.co.uk/) – really knowledgeable and helpful in my experience.

I’m not sure there’s any way to get a completely dry granite house down here – as you say it’s all about management. But echoing comments above, the worst thing you can do is seal it. Insulation and ventilation are the way forward. Have fun! (Where abouts in Cornwall are you)?

How about a completely opposite tack. Sort any rising damp issues with remedial DPC work, possibly dig and relay floor screed then use solid insulation on the outside and render over. Let the inside walls stay bare/breatheable until they dry out or use lime plaster to refinish.

Thanks @TheFlyingOx

STW a fount of knowledge as always!

I’m going here for a course this year through work http://www.scotlime.org/, handy as well as it’s just along the road from me.

I used lime plaster for my interior walls in Orkney, I limewashed them afterwards. It’s a wonder material, its porous and insulative. My croft was stone built with little more than clay bonding the masonry. I went on a lime course with the Scottish Lime Centre. It’s well worth enrolling on one to see how versatile a medium it can be.

aye, it was my local handyman that pointed (!) me towards insisting the work be done in lime, otherwise I’d have been none the wiser.

Did my house in Pembrokeshire in lime and it made the world of difference. NHL3.5 and roughcast. Inside was NHL3.5 either sponged up or with a putty and fine sand finish. Limewash to cover.
If I were to do it again I’d use hemp lime inside for insulation.
Rich.

PS if you pigment your limewash make sure you keep some to enable a colour match in the future – though any matching is difficult so white is my colour of choice now.

Lime is nice to use, I found it easy pointing the stone and brick of my place – 400 years old. If you have any concerns over it’s application then I also suggest going on a course, do what you can yourself to save some money.

Good to hear so many people understanding the importance of lime over concrete on old structures. It was a different story just as far back as the 90’s. 🙂

Lovely work there Mr Mcmoonter 8)

OP, cornish lime will be your people!

this is what i do for a living.
both plastering and stonework in lime.
the costs for pointing seem a bit high to me, but im in south wales and prices vary greatly place to place.

i absolutely wouldn’t use any kind of ‘breatheable’ coating,

well pointed stone should resist any weather in my experience. i would suggest hacking off any cement from the outside early in spring and leaving it unpointed for a month or so during dry windy weather to help draw out as much moisture as poss. there are lots of unskilled parts to the job you could do to bring the price down pm me if you like, and get some picks of the stonework up too 🙂

This is all very useful we have a 1740’s house with some interesting cement pointing in places that’s one falling out and allowing water ingress behind the brick, culminating in water pouring from the casement window surrounds in the recent South Westerly storms. It’s time to sort it it and it’s amazing the lack of knowledge amongst most of the local builders. Ironically the original pointing is absolutely solid!

honeybadgerx

Whereabouts are you? We moved into an old place in the borders at the end of last year, and whilst I’ll be doing some of the re-pointing myself, there’s some work that’s a bit beyond me, is there anyone you recommend? Also, if you know any good suppliers of lime it’d be appreciated, ta.

tbh I just buy it by the bag from Keyline in Newtown St Boswells when I’ve needed some, but I can recommend a local stonemason if you need – EIP.

They’re pretty cheap too, at least cheaper than I was expecting. Cost about £25 for a 25kg bag of pre-mixed NHL3.5,

I work for the company who produce K Lime a premixed lime render using nhl 3.5 and limestone sand. A bag will be about half this price or less and we supply through all the national merchants, Jewson, TP, Keyline etc as well as most independents.

http://www.k-rend.co.uk/products/range/K-Lime

If you want any more info my contact details are on the website. I’m the Scottish rep. Or my personal email is in profile

i pay about £17 inc vat for nhl 3.5 and all the builders merchants stock it round my way.
that is unmixed though and goes 1:4 with sharp sand