Lime mortar pointing

This is repairs to a Scots farm cottage some 200 years old which might well have been re-pointed sometime in the last century using beach sand !!
I hadn't spotted until recently that the CI down pipe at the rear of the ho use had split and was running water onto the wall. Split because the old s oak away and clay agricultural pipes were solid with mud! There's now a tr ench and big hole in the garden (thank goodness for neighbours who have a m inidigger !) to address the drainage.
The pointing will need to be re-done in a small area and my understanding w ith random rubble stone is that it should be lime based.
Can someone give any guidance on this please.
Thanks Rob
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On Friday, April 18, 2014 6:53:51 PM UTC+1, robgraham wrote:

ll have been re-pointed sometime in the last century using beach sand !!

house had split and was running water onto the wall. Split because the old soak away and clay agricultural pipes were solid with mud! There's now a trench and big hole in the garden (thank goodness for neighbours who have a minidigger !) to address the drainage.

with random rubble stone is that it should be lime based.

Quite so. 3:1 sand to builder's lime, just mix and use. The main difference s with cement mixes are: it takes ages to set/harden, you can mix a batch then continue using it nex t day it can accomodate slight wall movement without causing significant damage when it eventually fails it doesnt pull the surface off the stone like ceme nt tends to Speed of work is limited by its considerable slowness to harden - doesnt so und like this will be a problem in your situation, if its only a narrow str ip behind the pipe.
If you want it to look right, use the same sand colour and type as is alrea dy there. Red, yellow or white, soft, sharp or a mix. Occasionally you also get inclusions like shells or black specks. FWIW I dont think theres a big problem with beach sand, its much like the sea dredged sand builders & DIY ers widely use.
Cement & lime mixes behave like cement, and are not recommended. If you wan t to read more on why lime should be used, SPAB have info on it. Periodprop ertyforum also discusses it a fair bit, or did last time I was there.
NT
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On 19/04/2014 02:01, snipped-for-privacy@care2.com wrote:

Talking to a guy the other day who was re-pointing a Victorian house in sand/cement mortar after the front wall had been pressure washed rather than sandblasted. Have to say the end result looked pretty damned good.
He said they use lime mortar a lot these days, and cover it with a breathable membrane (landscape fabric?) for several weeks. Needless to say, this is mostly on listed buildings, so I guess it must cost a lot more
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On Saturday, April 19, 2014 9:41:06 AM UTC+1, stuart noble wrote:

lime & white cement look much the same

Lime and cement mortars are both very cheap, cement fractionally cheaper. The reason builders switched to OPC was the elimination of delays in building due to its quick setting.
Covering is only needed when frost threatens.
NT
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On Saturday, April 19, 2014 2:01:27 AM UTC+1, snipped-for-privacy@care2.com wrote:

This is the only point I would disagree with. If you use lime putty, and put the remaining mortar in one of the (air-tight) lime putty buckets, then you can continue using it next *year*.

Speed is not an issue for pointing at all. It might be for building a wall.

+1. It may actually need to be darker than previous sand (to allow for dirt on the existing pointing / brick

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On Saturday, April 19, 2014 12:09:14 PM UTC+1, Martin Bonner wrote:

Not normally an issue when pointing, but I have repointed brickwork where the mortar had fallen out all the way through, so the support of set mortar before raking more out did matter.
NT
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On 19/04/2014 02:01, snipped-for-privacy@care2.com wrote:

There is a LIME FAQ on UK SelfBuild site
but as stated a 3:1 mix with builders lime would suffice for re-pointing ... make sure you have a few dry days due as initial set time is considerable.
--
UK SelfBuild: http://uk.groups.yahoo.com/group/UK_Selfbuild/

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On 20/04/2014 20:58, Rick Hughes wrote:

So you need a crystal ball too? :-) Actually it seems they now cover with a breathable membrane rather than the sacking the Victorians used
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On Monday, April 21, 2014 9:53:08 AM UTC+1, stuart noble wrote:

Yes if youre too dense to check the weather forecast. Lime takes a few days to set.
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The snag with doing this - if the joints have been raked out first - is that any movement will result in cracked bricks etc. And most Victorian houses do move somewhat.
--
*Hard work has a future payoff. Laziness pays off NOW.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 19/04/2014 11:04, Dave Plowman (News) wrote:

Water pressure was enough to blow all the old mortar (well, just sand really) away, no need for raking. IME the movement issue has been overstated. My house should have fallen down by now if the purists were right
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On Saturday, April 19, 2014 1:46:56 PM UTC+1, stuart noble wrote:

Its frequently overlooked, and houses damaged as a result. Look round any Vic housing area and you'll find the damage cement does to soft brick. The long delay between application and damage means a lot of people arent aware of the connection.
NT
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Oh it won't fall down. Just possibly unsightly cracks. Of course it does depend on how strong the mortar mix used for pointing is.
--
*If all the world is a stage, where is the audience sitting?

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Saturday, April 19, 2014 4:00:30 PM UTC+1, Dave Plowman (News) wrote:

Many thanks guys for your advice. The colour/texture of the sand and a source of builder's lime now needs to be sorted out locally.
Rob
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On Saturday, April 19, 2014 10:10:21 PM UTC+1, robgraham wrote:

Masons Mortar, Salamander St, Edinburgh
http://www.masonsmortar.co.uk/knowledge/
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On Saturday, April 19, 2014 10:10:21 PM UTC+1, robgraham wrote:

The last time I was buying lime putty, I found the following sites that would deliver: http://www.lime-mortars.co.uk/ http://www.ecolime.co.uk/ http://www.lime.org.uk http://www.cornishlime.co.uk/ http://www.womersleys.co.uk http://stoneconservation.net (but I am in Cambridge, not out in the sticks in the Scottish Highlands).
Beware delivery charges - the reason I had that list of URLs was the spreadsheet working out the price/kg for approx 20kg lime putty delivered *including delivery*.
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On Monday, April 21, 2014 8:30:38 AM UTC+1, Martin Bonner wrote:

Thanks Adam and Charles
Not all old Scottish cottages are in the Highlands !! _I'm just 10 miles west of Edinburgh centre so Adam, that's a great link. Charles your list may not help me but I'm sure it will be of use to others - thanks to you both.
Coincidentally I only discovered recently that the largest lime pit at the time in Scotland was less than a mile away from me - it explains why the A71 takes a clear diversion at that point. Rob Rob
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On Monday, April 21, 2014 8:30:38 AM UTC+1, Martin Bonner wrote:

I dont understand why some folk pay high prices for ready mixed putty. A bag of builders lime and water is fine for pointing.
NT
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On Monday, April 21, 2014 7:56:14 PM UTC+1, snipped-for-privacy@care2.com wrote:

Bagged lime powder is usually hydraulic, that is, it sets quickly once dampened, and doesn't need exposure to the air. I *like* the slow setting nature of non-hydraulic lime. (Hydraulic lime also doesn't have the same self-healing properties - it all sets, rather than leaving a core of unset, which can set after the building has shifted.)
Also, I don't think it's a matter of "ready-mixed" putty. That's how it is turns out after you slake it. Slaking quicklime to give a dry powder is much more tricky.
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/ Oh it won't fall down. Just possibly unsightly cracks. Of course it does depend on how strong the mortar mix used for pointing is./q
And how much there is (depth) in the joints.
Jim K
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