Care of crumbling limestone

[frenchian]

Having lurked on here for a while, I now need to surface and reveal myself, as I need some help.

I live in France, in a house dating from late 19th century (I think). The bottom metre or so of the walls, up to cill level, is hard stone. This is non-porous, so works very well as a DPC. Unusual in these parts, I'm told. Above this, most of the walls are of traditional construction (outer skins of random stone glued with lime mortar, and a central space filled with mud), all covered with lime rendering. The front wall, though, is ornately carved stone. Whitish and softish - could be limestone, very possibly the local tufa stone.

Much of this stone is crumbling - funnily enough, mainly where it's in contact with the hard stone cills. Chemical reaction? Action of water, eg splashing? Whatever, I need to do something. It probably should be replaced by a stonemason, but I can't afford that. So I want to stabilise it, to stop further deterioration. I'm thinking of treating the stone with a consolidator - I've found products such as Durcipierre from Parex, or Drytreat 40SK.

Is this a good idea? Will it work? Do I have any alternatives?

Cheers

 

[Moo]

Not a clue, I'm afraid, but I'm just bumping your question back to the top of the pile to make sure that some of the experts see it.
xx

 

[MdB]

Welcome to the forum..

I'm very much a non expert - the following is based on what I've read here and could be wrong.

My understanding is that that you can consolidate the surface of sandstone by using limewater or other similar binders. The problem is that you aren't consolidating the whole stone, just the surface and this can mean that the whole front layer can come off rather than just small bits at a time and can cause the degradation to accelerate - not what you want.

If I remember correctly, limewatering sandstone to consolidate it was popular at some stage but isn't now recommended due to the layering issue.

My worry about using some bought in treatment would be what it contains. If it gives some sort of waterproof finish to the stone then this will trap water behind it which will cause you problems.

If it was me, I would investigate a lot further to answer these questions before doing anything.

 

[Feltwell]

I'm no expert either, but I'm sure I remember discussions on here long ago of using lime water to stabilise crumbling stone, but its effectiveness was very much in debate.

I would say search on "lime water" but the search facility on here (which I find to be REALLY poor - anyone else agree?) tells me that both words are too common for it to search on. Therefore you can conclude:-

- We talk too much about lime and water or
- The search engine is a snob and we will only search on what it deems to be "posh" words, such as Regency or Palladian.

Seriously, anyone know how to make the search engine group words together in a phrase and not just search on any of the words? Or am I being blonde again?

Edit - hit "post" at same time as MdB!

 

[MdB]

The search engine isn't the best.

There are a few articles using "limewater" which you can search for
http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=10106

or you can use google
http://www.google.co.uk/search?q=site:www.periodproperty.co.uk+%22lime+water%22
though this doesn't seem to index the forum.

 

[Moo]

It probably should be replaced by a stonemason, but I can't afford that.

That's a situation common to most of us most of the time, so you're assured of sympathy here.

But it prompts another question: would you be able to afford it in the near (or not too distant) future? If so, might it be worth trying limewater as a short-term fix?

 

[Penners]

Vous êtes bienvenu(e), frenchian.

I have no experience of this material myself, but it looks interesting: http://www.lime-mortars.co.uk/stone-restoration/stone-repair-mortar/5kg

 

[frenchian]

Welcome to the forum..

Thank you.

I'm very much a non expert - the following is based on what I've read here and could be wrong.

My understanding is that that you can consolidate the surface of sandstone by using limewater or other similar binders. The problem is that you aren't consolidating the whole stone, just the surface and this can mean that the whole front layer can come off rather than just small bits at a time and can cause the degradation to accelerate - not what you want.

True, but I'm gambling that this won't happen, in which case, I win. If it does happen, I'll be no worse off - same damage, just in one big chunk sometime in the future rather than bit by bit every day/month/year.

If I remember correctly, limewatering sandstone to consolidate it was popular at some stage but isn't now recommended due to the layering issue.

My worry about using some bought in treatment would be what it contains. If it gives some sort of waterproof finish to the stone then this will trap water behind it which will cause you problems.

I'm not planning on treating the whole wall, so there'd plenty of bare, breathing wall, which should cope with the damp issue

If it was me, I would investigate a lot further to answer these questions before doing anything.

Regarding limewater, I read about it while I was searching the web and, as you say, it doesn't get ringing endorsements. To be honest, traditionalist though I am, I was hoping that a more effective solution had been developed - perhaps something that NASA stumbled across - rather than what was probably used by the Romans.

@Moo, Unfortunately, imminent professional repair is unlikely - there are other, more urgent things in this house to spend my money on, such as the drainage. So, it'll have to be the next owner who has it done. In the meantime though, I feel I have a duty to stop it getting any worse.

@Penners. Merci bien, monsieur, and thanks for the link. That stuff seems very expensive, but I guess it's better than a handful of lime mortar slapped onto the crumbly bits (of the wall) - my technique of choice (or rather, necessity) so far. That's perfectly acceptable for the rest of the house (in fact, it's recommended) but looks a bit "rustic" on the fancy bits.

Maybe I'll have another look at limewater.....

Thanks, all.

 

[MatthewC]

I'm another non-expert, but I'd add a note of caution. <confession> Once, in my days of ignorance, I used some modern chemical on some sandstone, thinking that it couldn't do any harm and might slow the degradation. Well, it reacted and increased the degradation significantly, and I cringe now when I think of the harm I did. </confession>

So whatever you do, unless you get some really reliable expert advice, I suggest you try it on a little bit somewhere and then leave it for a year or two, just so that you can see the effect and thus minimize the damage if it's not suitable.

 

[frenchian]

I'm another non-expert, but I'd add a note of caution. <confession> Once, in my days of ignorance, I used some modern chemical on some sandstone, thinking that it couldn't do any harm and might slow the degradation. Well, it reacted and increased the degradation significantly, and I cringe now when I think of the harm I did. </confession>

So whatever you do, unless you get some really reliable expert advice, I suggest you try it on a little bit somewhere and then leave it for a year or two, just so that you can see the effect and thus minimize the damage if it's not suitable.

MatthewC, I, too, have done things I'm ashamed of - who among us hasn't? - though mine didn't involve sandstone. However, I shall be very prudent.

Regards