Lime mortar - advice for newbie please

[Lindyboo]

Evening all

I know that lime mortar is the stuff to use for repointing old brickwork but that’s about all I do know. A succession of numpties at chez shack have used cement mortar and of course that’s caused damage to the bricks. Hence I want to make a start at replacing it with the right stuff.

Advice welcome please on what type of lime mortar to use. I gather that there’s ready-mixed stuff and that appeals to me. Need a supplier that either delivers or is in Lincolnshire so it can be collected.

I’m sure this topic must previously have been covered on here but can’t find it.

Thanks
Lindy

 

[Bayliss]

I purchased a huge bucket of lime putty from RIDGEONS building supplies, there is one close to Kings Lynn. I just mix putty with my sand and horse hair, jobs a good'un.

 

[stuart45]

Using the correct sand is also important for the mortar to have the right pore structure.

 

[Zebra]

Oh gosh, there's LOADS of stuff on here about lime mortar. I'm usually the one on here asking the questions not giving the advice, but I'll try to chip in with what I can and see if others can help further!
Firstly, you might have to consider whether removing the cement mortar that has been put in will do more damage to your brickwork than leaving it in. Is it loose and falling out, or very well bonded? Do you have any pictures of the brickwork that you can post up?
When you say of course it's caused damage to the bricks, what has happened? How old is the brickwork also, and are they very soft bricks?
As for the right type of mortar to use, there's mainly two types, hydraulic lime mortar, and putty-based lime mortar. Hydraulic sets chemically after a shorter time, like cement does, and will even set while wet, whilst putty-based mortars take a long time to harden, as the lime carbonates through contact with the air. The latter is more breathable. Which is right depends on the application and on what type of brick you have. A very soft brick will need a softer mortar, since the problem with using cement is that it is harder than the brick, so causes the brick to degrade faster than the mortar. The mortar should be the sacrificial element, giving way if the wall shifts a bit, rather than the bricks cracking.
Yes you can buy ready-mixed stuff, I don't know what's in your area though. I've bought from the Old House Store before, and they deliver anywhere in the country. They also have a lot of useful guides on their website www.oldhousestore.co.uk.
I'm sorry this is such an inadequate answer, I wish I could say "use this stuff, you'll be fine!" But firstly you should consider whether it's a good idea at all to change it now the damage has been done.

 

[Me!]

I purchased a huge bucket of lime putty from RIDGEONS building supplies

Ridgeons sell lime putty! Is that the branch in Diss that you bought it from?

 

[MdB]

Before leaping in, post a pic of the wall you are considering working on. If the cement is in tolerably good condition, you could find you do more damage removing it then it would have done being left in place. On out old wall, I was lucky and the cement was very poorly fixed and it came out easily. Others have not been so lucky.

When mixing you will need something like 3:1 sharp sand to putty or 2:1 sharp sand to lime hydrate. I something like as different sands seem to need different amounts of lime to make a good mix. Cornish sand seems to need lime than elsewhere.

Rake out the joints to approx the same depth as their width and damp down lots (and lots) before applying the lime. Don't get the lime on the brickwork as you work as it will be a right pain to get off. Use a hawk and a "plasters small tool" (google it) to apply and watch a few YouTube videos to learn the technique. You will drop most of the mortar on the floor when you start. Keen moist for as long as possible and at least a few days so that it has a chance to dry slowly.

The above is very brief, read up as much as you can and go on a day training course if possible. It isn't difficult but it is something better taught if possible.

 

[Zebra]

On here somewhere I was recommended to use 2 parts soft sand: 1 part sharp sand: 1 part putty/hydrated lime.
You can also buy it ready mixed in bags or tubs. If using hydraulic lime you can't buy it wet, because it would set in the bag, but you can buy it as a dry mix.
I used a tuck pointer (again, google it), and increasingly, less and less went on the floor. Also used a churn brush a day or two after pointing, to bash the surface and create an even texture, revealing some of the aggregate.
Have fun with it!

 

[Keithj]

What they said.
Check also the manufacturer's recommendation for the lime you use. It probably needs to be kept wet for some days to give it time to carbonate. The normal process is to hang hessian or rag over it and to keep that well watered down.

 

[Bayliss]

I purchased a huge bucket of lime putty from RIDGEONS building supplies

Ridgeons sell lime putty! Is that the branch in Diss that you bought it from?

It was indeed, about 7 years ago.

 

[Lindyboo]

Thanks all for your replies.

Can’t post pics as suggested (insufficient technology) but the repointing would be for the entire house. I estimate about 100 bricks are so badly spalled they need replacing and about 20 have already been replaced – alas I was unable at the time to supervise the ‘builder’ so he bunged in cement mortar. (It amazes me that builders, particularly in rural areas with mainly old properties, never think of using lime mortar).

Most of the cement mortar elsewhere is loose as it was roughly daubed in over the old spent lime mortar so shouldn’t put up too much fight.
I intend to tackle the job a bit at a time and will occasionally be able to recruit someone to give me a hand, so it’s a very long-term project.

As an aside, about four years ago I was quoted £10,000 for a repoint (using cement mortar). House is tiny – about 30 x 30 ft and low walls.

 

[MatthewC]

It amazes me that builders, particularly in rural areas with mainly old properties, never think of using lime mortar.

Yes, it is amazing and rather depressing, isn't it?

I'll add a recommendation for Mike Wye (http://www.mikewye.co.uk/) who sell lime putty and various ready mixed mortars, and offer lots of good advice to purchasers.

If you've not seen it already, have a look at my blog http://houseintheenchantedforest.blogspot.com/

Matthew

 

[biffvernon]

Using the correct sand is also important for the mortar to have the right pore structure.

Well, yeees, up to a point. but remember that for most old buildings they used what was to hand. That is, they used materials that could be dug up within handcart distance. Old lime mortars are very varied.

 

[Zebra]

Most of the cement mortar elsewhere is loose as it was roughly daubed in over the old spent lime mortar so shouldn’t put up too much fight.
I intend to tackle the job a bit at a time and will occasionally be able to recruit someone to give me a hand, so it’s a very long-term project.
As an aside, about four years ago I was quoted £10,000 for a repoint (using cement mortar). House is tiny – about 30 x 30 ft and low walls.

A-ha! Well have a go then! If you think you're doing more harm than good, you can stop, but if you think you can get the cement out, and scrape out any loose lime (leaving in any lime stuff that is still doing its job) without damaging the bricks, then I would say give it a go! I must stress, I'm not the expert, and not really the one to advise, but I did exactly that last summer on my house. The cement came out without much of a fight, I did a lot of repointing, replaced a few bricks, and I have to say I'm pretty chuffed with it. You can do it a bit at a time, and it will cost you a fraction of the amount you've been quoted, but will cost you in time, energy and dedication! As far as suppliers go, I'd recommend the Old House Store in Henley, they were very helpful and supplied all my ready mixed mortars. Buy a bag and have a go, and if it's going well, then buy some more, rather than committing to the whole lot all at once! If you've got the time.....

 

[mr-squirrel]

Here is a basic guide:
http://www.historic-scotland.gov.uk/informguide-limeandcement.pdf

You need to use the right specification of lime mortar, using the wrong spec could be a waste of time and money. There is large regional variation in the types of lime mortar used.

It's not as simple as using any lime based mortar and all is well. As mentioned you need to use the right mortar for the situation in hand, location in country, exposure to weather, availability of sand, strength and water absorbancy of the bricks will have to be taken into account so discuss with a supplier. If the existing mortar is only failing due to age, it makes sense to have it analysed and put the same back. There are no "standard" mixes like there are with cement.

This might sound over the top but lime requires a higher skill level to cement. To get the correct end result it has to be specced, mixed and looked after correctly during the inital setting process. With that considered, the mortar you re-point with should last as long as the original and you've done the building justice. Lime does not tolerate fools like cement does, neither is it rocket science, but you do need to understand the fundamentals of speccing, mixing and using it. I would definitley recommend going on a training course.

 

[biffvernon]

Oh dear, I so don't agree. Working with lime is easy-peasey especially once you understand the basic chemistry and what the materials do.

 

[Feltwell]

Oh dear, I so don't agree.

ARRGGGHHHHHHH! :evil:

Not because you don't agree - it's because you so don't agree. I'm trying to stop my kids saying this horrible Americanism, and I'm failing.

Sorry Biff. Grumpy moment over, normal marginally less grumpy service will resume shortly!

 

[biffvernon]

We have to establish whether its etymology demonstrates that it really is an Americanism.
We have to establish whether this use of so enriches our language.
We have to establish whether this use is already covered by point 6 of the so entry in Fowler's Modern English Usage.

 

[worms]

Oh dear, I so don't agree. Working with lime is easy-peasey especially once you understand the basic chemistry and what the materials do.

Absolutely! Cement's a nightmare to work with, while lime is so forgiving! Mix a little or a lot, use it today or tomorrow...

I did a temporary repair round a new exterior light fitting on a cold autumn day a couple of years back. I needed something quick, just to keep the rain out and slapped on some old lime mortar I had made up for pointing and never used, but stored in a plastic container. Two and a half years on, the "temporary repair" is still there, limewashed over and now part of the fabric of the house. It has survived two extreme winters and one mild one. It experienced hard frost within a month of being put in. The mortar was a couple of months old and had been made from an old open bag of hydrate. It was slapped on quickly with cold hands on a bitterly cold day. Normal hydrate on an exposed west-facing wall, where the textbooks would say it really should be an NHL3 or so. I did everything wrong and nothing about it should have worked. But it is still there!

 

[Feltwell]

We have to establish whether its etymology demonstrates that it really is an Americanism.

It so does!

Ohh bug@er.......