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We’ve got an old sandstone and lime mortar wall in a barn. I could do with it not dropping as much dust everywhere (onto the workbench below!).
I’m conscious that old buildings need to breath so is there something easy I can treat it with to stabilise it? Ideally something I can spray on that won’t change the look of it - something like watered down PVA (but appreciate that’s prob not a great idea).
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And yep, I know it could do with re-pointing but that’s not realistically going to happen any time soon - too many other pressing jobs!
Wap on some boiled linseed oil. nice big cheap emulsion brush and scrub at it.
Not sure about spraying you might have to cut it with something like turps but its genuinely pretyy fast to appply by a bush because you aren't trying to create a nice finish.
PS thats not a workbench, it looks like a plastic crate.
Lime wash?
Yes I've used the stuff that skolt linked to and it is good. But as long as you have holes/ gaps in the walls dust is gonna blow out of there. That's probably where most of it comes from now so don't expect a massive differenc sealing over that lot.
Cheers - I'll give that stuff Skolt linked to a try. Doesn't need to be perfect but anything to reduce the dust a bit will help.
Hi specialist lime mortar contractor here.
The correct way to treat that to stop dusting is to brush back to firm material then apply lime water to the mortar. It's easy enough to make but you will have to as I don't know anywhere that sell it. Take some building lime powder and mix it in water like milk consistence then leave it till it seperates out leaving putty at the bottom and clear limewater at the top. Scoop that off and spray it on the mortar, let it dry and then keep repeating til your bored. The limewater will soak in and stiffen/firm up over time
The linked product is I think from the data sheet a clear acrylic paint. I wish I had a quid for every time a customer had put a modern material on a traditional lime mortar build and wished they hadn't, but there you go. Your wall!
Alternatively limewash - that linked article is good advice- or as you acknowledge, repointing.
Listen to Vader, do what he says. Anything else you will regret later.
Listened to @Vader - managed to cancel the order for that acrylic stuff just in time 🙂
Daft question - do I just want a bag of something like this to make my limewater? https://www.diy.com/departments/blue-circle-hydrated-lime-25kg-bag/35712_BQ.prd?ds_rl=1272379&gclid=EAIaIQobChMI_LSquvma-AIVBbLVCh0_dAmREAQYAiABEgLJjvD_BwE&gclsrc=aw.ds&storeId=1248
@dashed yes that would work as it is calcium hydroxide, but bare in mind that it's sold as a plasticiser rather than a building lime so if you had any intention to point or build later it's not produced for that and you don't now a. How strong it is and b. How it's been stored. If you want to build/point as well as make limewater get a bag of NHL 3.5 so you know it's strength and it should be fresh and correctly stored. Lots of brand names and fairly easy to source, I'm paying about £15 a bag for st astier or otterbein. If you are ever unsure what is in a product look on the safety and data sheets attached as PDF normally
Incidentally the ancient Greeks used to put limewater in their hair to stiffen and style it so you'll never need to buy hair gel again
Brilliant- thanks ever so much!
@Vader long shot but don't suppose you're working in Lancashire/Yorkshire? Trying to get a lime mortar specialist to quote for repointing my house and probably also lime plastering the interior...
Sorry @Bainbrge I am in Scotland and pretty much booked til 2024
Price wise as a rough guide a full cut out and repoint is likely to be £100 a M2, give or take and region depending. Scaffolding costs not included. I would expect top notch work for that. You will find cheaper but you get what you pay for. If you find someone always ask for examples of their work, photos or addresses so you can judge for yourself. If someone tells you they'll do it in a day, or it won't need covering, walk away. Likewise don't be afraid to ask and talk about the mortar mixes they would propose. Decent folk will happily discuss things like mortar and sand colours etc
Thanks Vader, that's helpful - i think everyone is booked to 2024...!
Ballbags, the forum just ate my post. Let's try again.
@Vader long shot but don’t suppose you’re working in Lancashire/Yorkshire? Trying to get a lime mortar specialist to quote for repointing my house and probably also lime plastering the interior…
I was about to ask this. I live in an 1890s terrace and have damp patches maybe a foot high at the bottom of interior walls. I thought at first it was tracking down from the chimney, I had a builder round who said "that's rising damp that, mate" (and regular readers will know my opinion of such a diagnosis).
Is it plausible to you - it is to me - that modern skimmed plasterboard and emulsion where a fireplace once was is likely to be the cause, it can't breathe as it should? Would punching a couple of ventilation holes be likely to help?
Am I going to cause big problems down the line if I just sand it down and paint over it (as the previous owner seems to have done)?
I appreciate this is wild speculation without seeing it, but I'd appreciate any steer you might have.
@Cougar yes I would be thinking about chimney ingress in that sort of situation. If there isn't a cowl on the chimney can, get one on, ideally an elephants foot type as they last forever although a Chinaman's hat will be cheaper. Without one it's basically a bucket sized hole pointing at the sky.
I think you are saying it's an internal wall ie shared with a neighbour. In which case do they have issues on their side or do they for example have a kitchen/bathroom there? I had exactly this in my previous 1800s hovel.
As you have plasterboard already then repainting that isn't doing any harm as it's non breathable anyway. With lime plaster you need to be thinking about clay based paints, basically breathable traditional materials.
If it's an external wall then think about a French drain up against the outside of the wall. Lots of older properties have wet soil up against the building. A simple trench lined with permeable membrane and filled with gravel-basically a gravel sausage- will keep the moisture away from the wall or let it out.
Lastly if you can have a look under the boards into the solum. Should be dry but previous master builders get up to all sorts of nonsense that can restrict air flow. Check your vent grills are clear too.
Edit yes I'd think about some venting in the old fireplace