Repointing a stone building

[Alane]

WJT

It is likely that it was rendered with a mix of lime and white cement which would explain it being harder than you expected. You can certainly limewash a lime rendered wall if that is what it is and Mike Wye says that it will just not wear as well on cement rendering but if you are unsure give Mike Wye a call - they are very helpful or have a look at their limewash factsheet first if you don't want to incur the cost of an international call. The tradesmen were correct in that you should not paint the lime rendering with masonry paint as that would stop it breathing.

 

[mister]

WTJ - no need to apologise. I've enjoyed reading about your experience and the debate it has generated. Unfortunately I am still none the wiser with my problem!  

 

[Cassis]

Hi Mister

In theory, the builder has not used the correct materials.  In practice, it could all be fine.  Technocem 32,5 is Calcia's most commonly used general purpose cement - also available in white, by the way. It contains a 'high performance' cement and no chaux.  It is for erecting bricks and blockwork, among other things.

Baticem 12,5 Ciment a Maconner has additives to make it easier to work when rendering and pointing brickwork and blockwork.

However, for stone walls Calcia advise lime for both mortar and for rendering - their own lime, of course, called Calcia Chaux Naturel Blanche NHL3.5.

There is a technical sheet which clearly shows which products Calcia say should be used.

Calcia Guide de la Maçonnerie

But don't panic - everything may well be okay.  You should have a 10 year guarantee from your builder in case of problems.

[WJT]

Robin, thank you so much for the information. Everything you have said makes very good sense in my situation. After reading your post, I will definitely not be too hasty and I will investigate further before making any decisions.

The stone macon has finally showed up today to start work (YEA! [:-))]). I haven't had a chance to talk to him because he and his men are hard at work [:D]. But I will have this discussion with him again and if I do decide to pursue with the other fellow the advise given of a trial area to see what is under the render is a very good one. Thank you ever so much again for taking the time to look into this. It is very generous of you.

Alane, thank you as well for the link and information on lime washing. If we decide not to remove the render, I think this is something I will try. It would look so much better if it is the same colour as the stone.

Mister, I do hope all works out with you, would be interested to know how you get on. Please let us know.

[Alane]

Robin

I know you said this would be your last post but I would be interested to know if the mason gave any reason as to why, if the rendering is lime as WJT has been told, it should be taken off the soft stone wall? Was it simply that as WJT doesn't like the look he should get it how he wants it or is there some underlying problem with partial rendering?

[Alane]

Robin

Thanks for that. I made the comment about white cement on the basis of WJT mentioning that the render was hard and that this seems to be the standard mix used by the builders around us. They tend to look a bit surprised at the suggestion of a lime and sand only mix and say it is too soft etc.

Thanks also for the comment about the oak as I was waiting until late winter to buy some joists from the local sawmill.

[Chris Head]

<<<Now about timber....did you know that standing oak parcels are being sold just at the moment at maybe15% higher price, which means that next year the price of French oak.....>>>

So the farmer who I'm haggling with tells me! Although I'm offering 20% more than the timber merchant he still wants more....I'm wondering if the Eastern European supply is faltering?

[mister]

Robin, thanks for taking the time and trouble to respond in such detail - I am most grateful. I am hoping that we won't have any problems with our walls, and that our French builder has good grounds for using the mix he has, but I guess only time will tell. We are returning next year to continue repointing the rear of the property and will try to resolve the matter before we proceed - hopefully my French will have improved by then.

I know that I ( and others ) have already imposed upon your time, so I won't expect any further replies but perhaps someone else out there might offer some additional advice on the interior finish of our granite walls. For example, is it customary to re-point inside, ie: leaving the stone work exposed? Or render over the top? If either is done with a lime mix will this cause problems with the exterior cement mix, ie: dampness being forced inside ( through the point of least resistance )? What sort of insulating qualities do these methods have ( if any )? Is plasterboard recommended under these conditions?

Although I have some limited experience of using similar methods in the UK, I have not previously applied these to old, and potentially damp, properties in France - so I am keen to learn from the experience of all those who have gone before me! Thanks in advance for any advice that can be offered.