Repointing a stone building

[mister]

Hi, first time post - so be gentle with me! I've just returned from France having employed a local artisan to reconstruct, in stone work, a collapsed wall / window and repoint the front and rear of the building. I admit to knowing little about traditional building techniques and am somewhat in the hands of this builder ( who came recommended by a number of local people ). He has used a combination of sand plus 'Calcia Technocem 32,5 Ciment Gris multi-usages' and 'Calcia Baticem 12,5 Ciment a Maconner' to rebuild the collapsed wall, and repoint the stone work. Having read on these forums the importance of using lime mixes on old buildings, I am beginning to wonder whether this chap has used the right materials! Nowhere on any of the bags does it clearly state Lime ( or Chaux ), and I've been unable to find any definitive information online. I am worrying unnecessarily? I would very much welcome the advice of anyone who has used these Calcia products. 

[londoneye]

i am sure someone will give you a better response than this, but the very term calcia suggests a calcium oxide or calcium type compound, which is surely not so different from chaux which is lime and thus calcium oxide (I think !) .... but happy to stand corrected on this one ?

[Cassis]

Calcia is a brand - Italian, I think - and they make all sorts of cement and lime based products.

The use of chaux is most critical in buildings/stonework that is porous.  If the wall is granite, for instance, then the use of some cement in the mix is fine.  Any idea what your type of stone you have?  If you pour water on it, does any sink in or does it sit on the surface?

[sharkhunter]

Cassis,  think it would run off the wall regardless. My feeble attempt at humour, please forgive.

[Alane]

These products are listed under "ciment gris" on the leroy merlin web site. From the Fiche Technique they both appear to be cement only products. The link is

http://www.leroymerlin.fr/mpng2-front/pre?zone=zonecatalogue&idLSPub=1159368226&renderall=on

 

[Cassis]

[quote user="hughmandy"]Cassis,  think it would run off the wall regardless. My feeble attempt at humour, please forgive.

[/quote]

No mercy! [:D]

[mister]

Thanks for all the replies. As far as I know the stones are granite. Hopefully, if the Calcia products are purely ciment based, that will make a difference.

[mister]

Thanks for sharing your experience. Like you I am no expert, hence the reason we hired a local builder to oversee the re-pointing. I am hoping the products he used are fine, but I have a horrible feeling they are non-lime based. Until I am able to get some definitive info on the Calcia products I won't know for sure. But like you I am dreading the prospect of having to rake-out the recent pointing if it is unsuitable.  

[Chris Head]

If the pointing is done with white sand and white cement would the wall still not be able to breath?

[WJT]

It appears our entire house has cement pointing as well as some rendering, inside and out [:(]. However, there is no way we will try and attempt to have it taken off or raked out. I believe it was done sometime in the 60's and it appears to have caused no damage. Obviously, I am very upset that this is the case and would much prefer the proper lime but it is as solid as they come. Anyone I have asked to have a look and quote on taking it off looks at me as if I was mad. I think it will be around for a few more lifetimes at least.

[mister]

Chris – Hopefully someone can answer your question. From what I’ve recently read on this and other forums, it would seem that lime pointing is recommended because it allows the building to ‘breath’. So presumably cement doesn’t do this? I’ve read that cement prevents the house from breathing and thus seals in dampness. Again, I don’t know. We are reliant on those people already living in cement pointed properties to pass on their experience. WJT writes of no ill affects to his / her property – so perhaps it’s something that I could live with? I would welcome other people, with cement pointed stone properties, sharing any problems they might have encountered with dampness, and how they’ve overcome this – how would they recommend finishing / insulating interior walls to combat this problem?

[legs_akimbo]

This thread may help in describing the benefits of using lime based mortars for repointing. Hard stone like granite however will not be adversely affected by using portland cement mortars as would softer type stone, as granite is not a stone that takes in moisture or needs to rely on evaporation of moisture, which should occur via the bed joints. Indeed I have seen many a propertys rendered in portland cement products that are constructed in hard stone with absolutely no adverse affects whatsoever after many many years.

 

http://www.completefrance.com/cs/forums/734214/ShowPost.aspx

[WJT]

I am not disputing the facts because I am aware of the need for stone to breath. However, I failed to mention that we located in the Perigord Noir and our house is built of the soft golden stone of the area.

[Cassis]

It's not just a breathing question - it is also because the flexing and movement in some old stone buildings requires the mortar to be able to give slightly, which limle based mortars do, whereas cement based mortars will crack.  A lot depends on the building in question, what foundations there are, if any, its construction method and materials.  In a solid building of impermeable stone with a damp course and without any movement, cement will probably not give any problems.  But few old stone farm buildings are of this type of construction.

There are many threads already on the subject: here are a couple more.

Chaux renderand mortar

Bag Rubbing

[WJT]

Well, I have felt bad enough about all of the cement but this thread really makes me feel terrible. [:'(]

I am not sure what we are meant to do because as I have said anyone that we have had look at it says it is just too difficult to remove. Any recommendations on making the situation better for our house?

By the way, I don't think there are foundations as such but is built upon solid rock and in fact one side of the house is built into the rock (rock being soft limestone).

[Alane]

WJT

If you haven't got any problems with the cement pointing then there is no need to do anything about it. I am a lime enthusiast but there comes a point when we can just make work when the effort would be better directed elsewhere.

If the joints have cracked and you have damp or decay problems then look at fixing it, otherwise spend your money and time on resolving any one of the other jobs that inevitably need doing on an old building. Keep an eye on the situation and if it starts to crack then think about re-pointing.

[Cassis]

I'm with Alan on that - sensible advice.

[WJT]

Thank you, I am sure you are both right because it would be a massive job. By the way we have everything to do so certainly not short of work. Hopefully the stone macon will be showing up this week (I have been hearing this for a while) to start the just first phase.[:@] We cannot do everything at once so will have to do it in phases.

I just went out this moment and took these photos so that you could have an idea of what I am talking about. The interior walls are covered completely with no stones showing like the exterior with odd ones not being covered. The house is meant to be from the 16th century so it it heartbreaking that someone decided to do this in the late 60's.[:(]

[IMG]http://i10.photobucket.com/albums/a120/HIF/P9210001-1.jpg[/IMG]

[IMG]http://i10.photobucket.com/albums/a120/HIF/P9210005.jpg[/IMG]

[IMG]http://i10.photobucket.com/albums/a120/HIF/P9210003.jpg[/IMG]

[Cassis]

Well, at least take consolation that they used white cement, not grey as they did on parts of ours.  Our back wall was a mish-mash of chalk, grey cement, white cement and nothing at all. 

Not all stonework was meant to be exposed - a lot is intended to be rendered over, some just leaving a few stones exposed for decoration.  Often depended on the quality of stones locally available.  Cement render and pointing is a divvil to get out - if it were mine I would leave it as long as it isn't causing any problems.

[WJT]

Perhaps it is better than grey but the white is one reason it drives me mad. If they had done it with proper lime the colour of the local yellow stone then I wouldn't have a problem. But then again it wouldn't be a problem removing either. I have thought about finding some sort of tint the colour of the stone to wash it with. I have mentioned this idea a few times but people seem to think it isn't doable for some reason. So if anyone has any suggestions would love to hear them.[:)]

By the way, other than the fact that I don't like the way it looks, I don't believe the cement render is causing any problems at the moment.

 

[legs_akimbo]

If it aint broke...dont fix it

[Cassis]

I'm sure there used to be someone here whose sig said "If it ain't broke - fix it 'til it is."  I liked that.  Could have been Jonzjob?

[WJT]

I do agree with your comments but just don't know how to overcome the problem. When we bought the house we did intend on taking the render off at some stage but since have had artisans, stone macons tell us it would be too difficult because it is very hard. Obviously , I am very upset about this and in recent months have pretty much come to terms with it. I have even planted a few Boston Ivy plants to eventually grow over the house (hopefully in my lifetime). As I said I would love to know if it could be tinted to match the golden stone it is built with. By the way,. I have tried to chip away at an area before just to make sure that it was stone and could see it was but didn't get very far because it was very difficult to remove and that was just a few inches [:(].

I also wanted most of it taken off inside as well, particularly the old pigeonniere that is our staircase. But again have been told the same. The interior walls are smooth and are painted.

As far as the history of the house, I too would love to know, unfortunately we have no photo's. The only real information we have is an elderly man in his 80's and his family just happened to visit on holiday two days after we moved in and told us he lived here as a child and he and his siblings were born here in the house as well as his Grandfather.  

I don't think dressed stone is that common here in ordinary farm houses. So is interesting that the house has some. I was told that during the late 60's it was quite fashionable to render and leave some stone showing in this area. [:(]. I have seen it on some other houses here (Perigord Noir) in the Dordogne.

The house has been changed and altered greatly over the years so very difficult to know exactly what it was. However, we are told that most of it dates back to the 16th century but there are remnants that go back much further so we suspect it may have been a ruin and a lot of it was rebuilt in the 16th century and of course greatly altered and ruined in the late 1960's early 70's. There is one wall with a fireplace that we have been told is possibly 1000 years old and has markings of the Knights Templar. By the way we are having it restored, you should see what they did to it during that wonderful 60's era. It is backed with very ugly red brick tiles as well as the hearth built up with the same tiles.[:'(]

There is an old bread oven adjacent about 10 feet away forming an L that luckily doesn't have any render so gives us an idea of what the house would look like without the render. by the way the house is not very large, it is only a little over 170 metres of habitable space.

There you go, I am sure much more information than you wanted to know.[:)]  If you have any suggestions on what we should do or what you would do in our position, I would love to hear them.[:D]

[Alane]

WJT

Have you thought about applying limewash? It is available in colours as well as plain white. One site with a colour chart is www.mikewye.co.uk who also has factsheets on traditional building methods.

[WJT]

Robin, now I am really confused because I have been told by several people that it is cement. Today we had the chimney swept and on the side of the van it listed the work that they do and taking rendering off of houses is something they do. Anyway they did take a bit off to see what it was like and they said it is not cement but is in fact chaux. It is very hard and thick but according to them not cement. However, it does appear that the inside is cement and any pointing that is evident is cement as well, grey at that [:'(].

He does seem to think he can take it off and will give me a price. Perhaps in the past the stone macons I have asked just couldn't be bothered (unfortunately like many things I ask for devis or prices for here [:@]). I am a little worried about what it will look like underneath and the state of the pointing and of course the stone once they finish with it. But in any case it is good news that perhaps it isn't cement after all.

Thank you Alane for the link and that is exactly what I was trying to say previously, about colour wash and a lime wash does sound like a good solution if it would work. I wonder now knowing that it isn't cement if it would be possible. The men that were here today didn't think it could be painted but I don't know if they understood what I meant.

Mister, I am really sorry to have hijacked your thread [:$]. I really should have started a new one. I do hope you have found the answer to your question and hopefully your builders are using chaux. But as others have said perhaps it wouldn't make as much difference if your stone is granite unlike our soft lime/sandstone.