Flaky sandstone workshop wall remedy

[Bluekingfisher]

Not a "wood" question, however it does concern my future woodworking.

Before I set up shop I want to address the walls in my garage workshop. The internal walls are constructed from sandstone and lime mortar, some of which is becoming a little flaky and beginning to crumble in places. The walls are not drawing dampness, nothing sinister nor underlying. The issue is just the result of decades of humidity fluctuation.
I was just going to apply a cement wash to bond the surface but wondered if I should apply a more technically advanced base coat first? Or indeed a final coat!
Would a PVA/ water solution be suitable or a silicone based stone/brick protector be preferred? The PVA I suspect will not penetrate although should leave surface "tight" suitable for for the cement wash if desired, whereas the silicone will penetrate although I am not sure if the silicone seals the surface ???

If anyone has encountered, and remedied the problem I would appreciate your input. Its' a dirty job I only want to do once.

Thanks boys & gals

David

 

[Argus]

Don't know if this is any use....
Many years ago.... about 25 or more.... we had an 'ornamental' brick chimney 'feature' in the lounge of an old house.

It looked good at the time but was prone to shedding grit all over the floor.
I used a paint-on masonry stabiliser solution suggested by Thompsons which solved the problem permanently.

I found them to be very helpful when they got a grasp of my problem.
Here's a link to their page: worth a chat.
https://www.thompsonsweatherproofing.co.uk/admixtures/

Good luck

 

[MikeG.]

I've less experience with stone than with most other building materials, but I'd question your choice of a cement wash. That will fundamentally alter the way that wall deals with moisture (and temperature differences), and could well cause far worse problems than those you have at the moment (as indeed could any impervious sealant). I would suggest you speak to the technical department of one of the lime suppliers, such as Sudbury Lime (Suffolk), Ty Mwr lime (Wales), or, more likely, Scottish Lime Centre Trust. This is everyday stuff for these guys.

 

[John15]

Cut flakey surface back to sound stone?

John

 

[Bluekingfisher]

Argus, MikeG, John15 - thanks for the input gents, food for thought.

My issue sounds similar to the one encountered by Argus. I will look at the link you sent.

Cheers gents.

David

 

[Argus]

David,
..... searching way back in the memory-banks, I recall the the Thompson's product that was recommended was a stabiliser intended to consolidate gritty rendering prior to painting.

Not sure if it is externally-durable in its basic form without paint, but it didn't matter to me as my problem was indoors and when dried out it was completely transparent
I think that one or two coats solved the grit-on-the-floor issues for good.
Sorry that I can't recall the product name, but Thompson's technical guys should help.


good luck

 

[Bluekingfisher]

The walls in need of stabilisation are also indoors, so my issue is virtually the same as you encountered.
I haven't had the chance to speak to Thompsons yet.
Perhaps the quarter century since you treated your wall has seen an advancement in the product? Not a job I am looking forward to to be honest dragging all my gear into the middle of the floor, covering it, removing the flaky stuff then treating is not a job I want to do more than once.

Did you spray the product or was it a good old fashioned brush and bucket job?
David

 

[MikeG.]

Sealing a permeable stone wall with an impervious outer layer is a seriously bad idea. I don't have the slightest doubt that you will create a far worse problem in a few years than the one you have now. I strongly urge you to reconsider this plan.

I'd also add that thanking the only person who you think agrees with your chosen action shows that you didn't ask this question looking for advice. You asked it looking for confirmation. Stabilising sand & cement render (an impermeable product) is the polar opposite of stabilising a porous sandstone. And there's a huge clue in the mortar.

 

[AndyT]

Mike's right.
We've got lime render on our house, using Ty Mawr products. Really good, really durable - but you have to listen to the experts and not mix in Portland cement or waterproofing chemicals.

The Ty Mawr site has a product selection guide which covers common applications if you want to read a bit more before approaching a supplier or installer.

 

[Argus]

As you asked the question, David, the wall was a chimney breast, floor to ceiling made of rough-textured brick and some fancy pointing.

It had a good brush-down with a stiff brush to get the loose stuff off followed by a good vacuum (I had an industrial vac in the workshop then).
The Thompson's stuff was dobbed on with a cheapo disposable brush - a bit like painting Artex. It was a pale liquid, as I recall, that dried colourless and transparent.
My wife did the actual job as she had the patience to work it into all the crevices. I think she said that it had a memorable pong which did wear off after some time. The desired effect was to consolidate the loose surface grit that fell off as soon as you looked at it.

However, I am feeling some strong caveats about the suitability of this idea, so please do some research. As I said, it worked on my old ornamental brickwork, the brain-child of the previous owner.

 

[owen]

I'd be ringing sovereign chemicals about this one, in the past I have used a product of theirs called "facade cream" or something like that, on external sandstone walls.

 

[Bluekingfisher]

Thank so again all for taking the time to respond. Very much appreciated.

David

 

[Bluekingfisher]

Mike G,

It seems I have upset you for not thanking you? when infact I did. I thanked you all by name.
I asked for information from those who had experience of a similar matter, hence the reason why I had "thanked" Argus on his second time of responding.
Whilst the forum is a very useful site for sharing and exchanging experiences it is often wrangling when some offer advice, often regurgitated from others, or have little or no experience themselves seeking a clicked thank you as a badge of honour.
With regards to the link you shared, it is primarily aimed at buildings of national interest or significant importance. I have, in the past had dealings with them. From the outset they required personal information prior to offering any advice, something it did not wish to divulge.

In any case, I have thanked you for your input, as response is always greatly received.

Have a great weekend

David

 

[MikeG.]

Mike G,

It seems I have upset you for not thanking you? when infact I did. I thanked you all by name.
I asked for information from those who had experience of a similar matter, hence the reason why I had "thanked" Argus on his second time of responding.
Whilst the forum is a very useful site for sharing and exchanging experiences it is often wrangling when some offer advice, often regurgitated from others, or have little or no experience themselves seeking a clicked thank you as a badge of honour.
With regards to the link you shared, it is primarily aimed at buildings of national interest or significant importance. I have, in the past had dealings with them. From the outset they required personal information prior to offering any advice, something it did not wish to divulge.

In any case, I have thanked you for your input, as response is always greatly received.

Have a great weekend

David

I'm an architect, and have dealt with hundreds of traditional buildings over the years. Of these, only half a dozen to 10 have been sandstone. Hence my "less experience with stone" comment. I'm guessing that that is still more than anyone else here, and probably more than everyone else combined. It upsets me to see people heading down a foolish route, and more of our built heritage being ruined by inappropriate interventions. The thanking thing doesn't upset me in the least. It was merely indicative of someone with a closed mind, determined on a course of action which is fundamentally flawed. You don't want to hear my advice. That's fine. My advice is correct, though: slathering a stone wall with cement slurry is never the correct answer. Please sign your work and date it, so that the next person along knows who to blame.

 

[user22161]

Sealing a permeable stone wall with an impervious outer layer is a seriously bad idea. I don't have the slightest doubt that you will create a far worse problem in a few years than the one you have now. I strongly urge you to reconsider this plan.

I agree. There's maybe another way of attacking the problem, by lining the walls. I have a single brick garage so fixed slate lats vertically on dpc and then lined with 1/2" plywood. Was going to use OSB but managed to find second hand 8 x 4 ply sheets @ £10 each. No signs of damp and tools hung on walls don't rust.