Sandstone wall - repointing & repairing - Advice on lime mortar mix

[katmark]

Hi,

I have a wall built of random sized, undressed, sandstone bricks around my house, about 18'' thick - probably built in the mid 60's. It is in various stages of disrepair, ranging from loose pointing to totally loose stones.
I have bought a pointing gun (from turptech tools) and have been using this to put a single application of lime mortar into the missing pointing and the same mix to rebed the totally loose stones.

The mix I have been using is 3 parts BUILDING SAND:2 Parts Hydrated Lime:1 part OPC.

What I need to know is - am I using the right mix ?

Any other tips would also be appreciated

The manufacturers of the pointing gun recommend use of building sand over sharp sand as 'sharp sand does not flow under pressure'. The lime mortars I've seen on the 'net all seem to recommend SHARP SAND though !

I have a large area of walling to do on both sides and, as I'm trying to do lots of work on the house myself, i need something fairly fast - hence the 20 quid investment in the pointing gun - it was taking me an age to point with a hawk

Thanks to anyone taking time to reply

Mark :;):

[lutonlagerlout]

no point using a lime mortar and putting cement in with it mark
unless the original wall is built with cement?
if you want to do it with lime mortar you need to get hydraulic lime and you do need a sharp sand mix,the proper stuff would be lime putty and a really coarse aggregate like grit sand but that is unrealistic
soft sand is too weak for most applications except10 mm perps and beds in modern brickwork
a picture of the wall would be handy

ps hydraulic and hydrated lime are 2 seperate things,hydraulic lime can set hard under water

[katmark]

Thanks for that LLL,

I've started using builders sand (as I had a half a dumpy bag left over) and bagged lime from a builders merchant (is this non -hydraulic ?) I've already done some of the wall, but I'm more than willing to listen to the advice of people who know and change what I'm using ! I'd read somewhere that the OPC was needed to get the mix to set ?
How can I tell what the wall was built with - the 'mortar' seems to be quite soft and crumbling.

If I get home from work in the daylight tonight, I'll take some pics and see if I can work out how to post them !
I'm inept at Computers as well as DIY building jobs !!

Thanks again
Mark

[lutonlagerlout]

well in the "old days" all walls etc were built with lime putty,this being chalk that is fired in a kiln till all off the carbon dioxide has gone,this is then quick lime a very corrosive substance
water and sand were added to this and it was left in pits for up to a year
you then took what you needed added more water to make it plastic and built with it
the big problem with this stuff is that it takes ages to set hard and you have to keep it covered for 6 weeks and mist it daily to stop it going off to quick
obviously building with this material is very slow and normally nowdays only happens on heritage jobs
once the wall was built it was raked out to 10mm depth and the front 10 mm was tuck pointed which is a very elaborate process and too detailed to go into here
anyway cement ( a mixture of chalk and clay fired together) has been around since roman times,but it was bloody expensive
but hey presto in the 30's (i think) a way was found of making cement cheaply
all of a sudden concrete became de rigeur and very soon architects realised that houses ,sky rises in fact everything could be built much more quickly with a cement based mortar

but what they didnt factor in was that lime mortar was flexible and could self heal in the event of cracks
also as lime mortar was exposed to the elements it drew CO2 from the atmosphere and actually recalcified
this is why there are still plenty of buildings from the 17th and 18th centuries around
the new fangled portland cement was great but had a tendency to crack at the slightest movement
chances are if you point your wall with a cement mortar it will crack again in due course,water will penetrate and when it freezes cause more cracking
hydraulic lime is a bit specialist but some BM's do stock it or can get it
hydrated lime is used to enhance the plasticity of mortar and give it a nice light colour but on its own will not set
maybe sue at easipoint has a special mortar for this type of application
i think its
www.easipoint.co.uk

cheers LLL

[katmark]

Help ! How do I post a pic ?

[seanandruby]

....look at noticeboard.

[lutonlagerlout]

re: the gaffer

You will need:~

The photies stored somewhere on the web
The url (address) for where the photies are stored
About five minutes free time
A little bit of patience


Pleasae don't upload effing huge photies that take three days to download - you'll only annoy your potential readers. The Brew Cabin is set up to have a width of 720 pixels, so PLEASE PLEASE PLEASE keep your photies to a maximum width of 600 pixels. If you really want to impress people with ginormous photies, just provide a simple link rather than distort the carefully designed layout of the Brew Cabin.


So: you have uploaded your photies to your own webspace or a website somewhere out there in cyberspace. To make them appear, as if by magic, in the Brew Cabin, you need to include a little bit of code in your message. Here's the code...

Code Sample
[img]http://www.Name OfYourWebspace.com/photie01.jpg[/img]


You MUST use the square brackets around the IMG tag, and you must use a closing tag (ie: /IMG within square brackets. The square brackets are the two keys to the right of the P key on most keyboards.

You need the FULL url, so that means the http bit, the www bit, all and any backslashes or forward slashes and the full name of the photie itself. The easiest way to do this is usually to navigate to the photie using your browser, whereupon the FULL url should appear in the browser's address bar. You can copy and paste it from there - easy!

Note: due to the nefarious activities of certain one-handed surfers and eejits peddling drugs, the code does not allow photies from dynamically created sites to be uploaded. This prevents the Brew Cabin becoming some sort of animated billboard for all the crap you don't want. It also means that SOME photo-sharing sites are "out of bounds" and will not work with the above code.

If all else fails, you can always staple your photies to a ten pound note and email them to me at the address given on the website and I'll upload them on your behalf.

cheers
LLL

[matt h]

Nice history lesson LLL, for Heritage jobs, we send a sample of the existing mortar to the lime centre in winchester, and they send us back the correct mix configuration... bloody amazin what you find in some old mixes!:D

[katmark]

Hi,
thanks for that.
I have a virus on my home PC, so I can't post from there (think I'm going to have to reformat it -nightmare !). Sneaking on at work now!
All this lime stuff is quite interesting, I've done a bit of digging on the net on various restoration & conservation sites and opinion seems to be split with gauging with cement or not !
Easipont do carry a 'historic mortar', but it is quite expensive.

I've bought some various sizes of tuck pointers off the local market (£1 each !) & I think I'm going to try and source some hydraulic lime and use this. Will 'moderatley hydraulic' be my best bet ? I've seen both 3:1 and 6:1 mixes recommended though ? Any views on this ?

I'll abandon the pointing gun, however, will I be able to use building sand + lime for the really thin joints (some are only a couple of mm wide). The grit in the sharp sand stops me getting the mix into the joints (see below !)

I got some small bags of sharp sand from B&Q the other night & it is very different from the dumpy bag I got from the local builders merchant some time ago. The bags contained quite large grit sizes (looks like pic on this site), whereas the dumpy bag I'd gotten earlier just seemed more course in grain size. Was this possibly plastering sand ?

As we've had the first frosts up here in West Cumbria I'm not proposing to do any more on this job until the spring - plenty of other jobs to keep me busy over winter !

When I get my PC sorted I'll post some pics and addresses of the sites I've looked at, in case anyones interested.
I'll start a new thread.

Thanks again for the advice
Mark

[lutonlagerlout]

procrastination is the thief of time mark!

it would be stronger with lime and sharp sand as the grains are more angular
cheers LLL