Lime mortar mix

[Alder]

Can anyone advise me what are the ingredients and proportions to make lime mortar mix.
Thank you,
Russell

 

[MikeG.]

That is a much more complicated question than you think. Much traditional lime mortar was made using chalk rather than sand. Are you planning on using putty lime or NHL? If this is for brick laying, then are you doing it, or getting a brickie in? Or are you just re-pointing? If the latter, you need to take a very close look at the existing..........does it use sand or chalk? If sand, is it sharp (ie does it have large particles in it?).

 

[Alder]

Thank you for the reply, it is with pointing in mind.
I suspect that there is chalk in the mix but will have make a closer look. You are right it is more complicated than I thought.
Russell

 

[chaoticbob]

I recently stripped the plasterboard from the walls of my living room to reveal the original limestone. I did a lot of research and it is indeed complicated! Eventually, because of the age of the place (no DPC or anything) I got in a plasterer who does a lot of restoration, and he advised that an NHL 3.5 /sand mix would be fine and breathable for the areas which we wanted plastering. He said an NHL 3.5/sand mix, 1 part NHL to 3 sand would be good for pointing the areas where we wanted exposed stonework. That's working so far!
Rob.

 

[Beau]

Re pointed our place with NHL but cant remember the numbers off my head. Quite a lot of variables but these guys gave me all the information we needed and it may well be in the list https://naturalhydrauliclime.net/faqs/

 

[MikeG.]

I recently stripped the plasterboard from the walls of my living room to reveal the original limestone. I did a lot of research and it is indeed complicated! Eventually, because of the age of the place (no DPC or anything) I got in a plasterer who does a lot of restoration, and he advised that an NHL 3.5 /sand mix would be fine and breathable for the areas which we wanted plastering. He said an NHL 3.5/sand mix, 1 part NHL to 3 sand would be good for pointing the areas where we wanted exposed stonework. That's working so far!
Rob.

Even with stone, and a simple mix like that, it's more complicated than you think. You have to check your sand's clay content. An experienced guy will just grab a handful of sand and squeeze it, and judge from that. The amount of lime required is then adjust, or the sand is adjusted. Like I said, this isn't a straight-forward question.

As this is re-pointing, I'd just point out to the OP that the mortar should be "ironed in" (ie compressed), and not just struck off.

 

[Lons]

Non-hydraulic lime is most commonly used and is made from calcium carbonate which is basically chalk / limestone, it's often called hydrated lime and what you'll find most at the builders merchant.
The last listed building we converted which was an extensive job, we used that as it was " "recommended" by the planning officers.
That was 13 years ago and I was there last week as the owner is a mate, the stonework and mortar is as sound as when we put it in. BTW the mortar wasn't ironed in despite our protests, it had to be struck flush to match original again at the direction of the boys with the clipboards.

Just a word of warning, lime is horrible caustic stuff so don't breathe it in or get it in your eyes or you'll know about it, easier said than done as when mixing it floats around in the very lightest of breeze. your other half won't like the state of your clothes either.