Much of my house is pointed with a lime and sand mix that I did over 20 years ago following the advice of my neighbours. It is as good as the day it was done. There is no way that I would ever consider adding cement to pointing. The Grand Designs wall must have had a problem either with the mix or the weather. If you want to quote Grand Designs I suggest that you listen carefully to what Kevin McCloud has to say on the subject.
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Due to the different expansion rates and amounts with cement and limestone they will always pull apart. Only handy thing with cement is the stone comes off clean allowing it to be re used easier than the lime which will bind to the lime forming a proper bond.
A lot of 150 year old buildings have fallen down, there is no strength in these old houses just 1m thickness, ours are 1/2 m. and lots of cracks due to no foundations.
If they had used even 10% cement the house would have been sound.
Very few old buildings around me had any lime pointing, my own buildings used only mud. As I keep repeating lime and sand are perfect, cement will introduce more problems than it cures.
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Lots of cracks due to no foundations will not be improved using too harder mix of either lime or cement. Cement being harder will not help. NHL 3.5 or 2 allows for structural movement which you will not stop. There is a reason why brick/block walls require expansion joints when cement is used and not when lime is used.
In your house you can do what you want. Telling us we are all wrong and donât know what we are talking about is just rude.
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We cut 12 windows to make our building into a house, there was a lot of mud left over so we mixed it with cement for the returns and then rendered that with Enduit to give a smooth surface and painted that with white gloss.
Done 11 years ago still perfect, perhaps not so white cos French paint does not stay white.
We base our workings on what my wife`s father taught us, not wrong.
Probably working differently is not wrong either, just different.
Barry
Good to see people using lime on old masonry. Iâve written a book on the subject.
As to mixers, ideally one should use a âpan mixerâ but they arenât often offered in many bricos. The ordinary type of mixer works best if you remove the blades, as it allows the mic to âroll overâ not unlike making a meringue! As the machine rolls, the mix peels off and âsplatsâ onto the bottom, which is the proper way to mix lime.
Unfortunately, a lot of Brit immigrants still use the cement/ lime mix, but they use the wrong lime! On the shelves of UK and Irish builders merchants the lime offered in plain âhydratedâ which isnât hydraulic. The equivalent hers is " Chaux aĂ©rienne" (air lime), which isnât readily available in bricos. When they ask for lime, they end up with NHL 5 and add it to the cement, making the mic even stronger. The cement/lime mix in the Uk is not recommended any more, except for new build.
What a lot of supposed tradesmen donât know is that cement mortars and concrete have the same characteristics as steel, and contract/ expand with temperature, while the lime mortar/clay (agile) built walls donât move at all, except for natural subsidence, resulting in severe surface cracks and internal damp.
Have you ever used lime concrete?
regards
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Unfortunately, some people use âlime puttyâ and sand mix, which has no strength. If you use lime putty known in France as " Chaux aĂ©rienne" you have to add a pozzolan, which is often volcanic ash or soft brick dust. This additive makes the putty hydraulic, but itâs hard work mixing it!
Using any kind of cement can cause the stone to decay, because it prevents moisture from leaving via the pointing joints, forcing it through the stone.
Soft brick is the result of badly fired brick on the outer edges of the kilns. In the past, they were used for internal work, as they crumble with damp and frost. Most of the flat âromanâ bricks here are mostly soft brick.
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Hi Vincent, I have reasonable success using a tub mixer , a horizontal job made in Italy and also sold rebadged by the belle company.
https://images.app.goo.gl/Yjw7ENHd744WcEnL6
Iâve always used my trusty old Belle mixer, with the paddles (itâs only got 2). Works just fine. Does concrete tooâŠ
Interesting topic 
, over the next year odd I have the two buildings below to re render, they were done in pink lime plaster at one point but have been patched up so much with in part cement that it is all coming off to get re done and windows and doors reinstated, should be fun 
.
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Look forward to seeing the progress. be ready to go as soon as the weather is right as the window of working (from too cold / wet to too hot) can be very short, we missed it entirely last spring!
A friend of mine who has the dealership for Saint-Astier in Eire, supplies clients with large sheets of hessian for protection against direct sun and frost.
In fact, the 5° C rule also applies to cement building work, but a lot of ignorant tradespeople just ignore it. It can have disastrous results!
The EU advisory committee has not too long ago reorganized the specs. Before that there was a NHL 5Z, the Z meaning fortified with white cement.
Now it is shown as HL but not natural. There is also an âFLâ spec, which means âformulated limeâ.
That particular spec was due to input by the Traditional Lime Co in Eire who are on the committee.
There is some suspicion about the Portuguese NHL and a UK one, which are suspected to have gypsum added.
There is a good quality German NHL available.
You can rectify a render by using lime paint.
It comes ready made in pastel colours, or you can make your own, using ochre etc. The problem with that is repeating the mix!
When using lime-wash you have to make sure you get the amounts of lime and water right.
From powder, (non hydraulic) it is one mime to three water, then one to two there after. On a smooth surface, you have to brush it when still damp, with a dry brush and up and down strokes, which removes the original uneven brush strokes.
If you use lime putty/paste it is first coat one lime to two water, as the putty already has water.
When you buy the putty (UK) pate (FR) it come guaranteed to be at least three months old. If kept under water it improves with age, becoming finer in texture.
To make your own, just dump some powder non hydraulic lime in water, and keep it with a head of water. It can be used as a fine plaster, which when kept damp, can be worked to get a very good finish. It must be allowed to dry very slowly, which a lot of people donât have the patience for!!
NHL 2 can be used as a wash, but because it is hydraulic, you canât keep wet for long, as it will start to set.
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What is meant by this? I am looking to make some limewash so just seeking clarification.
One lime to 2 water.
Important note is PPE. Eye protection is a must as are gloves. Lime putty (pate) (chaux arienne) is very caustic and will burn, never rub your eyes so good to get an egg cup and water ready as an eye bath sould a splash occur.
So do I add one lime and 3 water? - what is the one to two thereafter referring to?
Sorry re read your post, first coat is a thinner 1:3 to penetrate deeper into substrate to consolidate better before the slightly thicker coats are applied. Depending on the friability of the substrate you may use 2 thin coates.
My OH had a nasty lime burn on his arm & our MT recommend using milk to sooth & clean it, not water as that makes it worse. The milk did the trick.