Pointing sandstone

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fernicarry
Posts: 123
Joined: Fri 22nd Jan, 2016 11:10 am
Location: Argyllshire

Pointing sandstone

Post by fernicarry » Fri 2nd Oct, 2020 6:45 pm

A job I've been meaning to get around to all summer, well actually for a few summers now.

Its a stone rubble building but the front doors and windows have sandstone block details around them. There is a sticky out bit above the living room windows where the mortar is completely washed away on the upwards facing joints. When it rains heavily from a certain direction we get water coming in through the top of the window recess so seems likely the pointing is a contributing factor.

I assume this is a lime mortar job? Have I left it too late in the year to be starting? I actually might not be able to start until more like the end of the month provided Princess Sturgeon lets me go on my holidays at half term.

What materials should I use? I have a bit of an aversion to mixing things up for myself and I see Anglia have pre mixed 15l buckets of coarse stuff for pointing, so that sounds ideal. They also have a bewildering array of bagged stuff including something recommended for fine joints. The joints are pretty fine -- about 4mm if memory serves -- so wondering if the coarse stuff would be suitable?

In terms of working it in, there really is nothing in the joints, you can easily prod something in for a good 6 or 9 inches. Should I be looking to pack mortar in to fill all of the depth?

I hates wet trades...

Thanks all.

Feltwell
Posts: 5627
Joined: Sun 18th May, 2008 7:28 pm
Location: Shropshire, England

Re: Pointing sandstone

Post by Feltwell » Fri 2nd Oct, 2020 7:42 pm

I can't comment on Anglia lime, but I've been using this for pointing and it's very easy to use - just mix it with water in a flexi-bucket with a paddle mixer, just as a plasterer would use for modern plaster.

https://www.lime-green.co.uk/products/l ... ime-mortar

It goes off quite quickly, but of course it takes longer the deeper the part you're filling. They do a 1mm sand version, SG, that it OK in fine joints, we've had joints down to 3mm and it's been OK. Slow job to fill them though, and it necessitated me grinding down finger trowels to be extra narrow to enable this!

Is it too late in the year? The only 2 factors to worry about is if it's raining too much to allow the work, and can it go off before frost gets to it. At the moment we're ok here, although we had a clear night the other night and did get a little bit of frost. Covering the finished job in hessian helps protect it.

Usually you do want to fill to the full depth, yes.

a twig
Posts: 607
Joined: Sun 6th Oct, 2013 10:18 pm

Re: Pointing sandstone

Post by a twig » Sun 4th Oct, 2020 12:26 pm

Agree with Feltwell entirely - I have also ground down finger trowels, until a local stone mason put me onto using a small plasterer's trowel - such as this:

https://www.ebay.co.uk/itm/PLASTERERS-S ... 1895226595

Our ashlar had 1mm joints and I found that ideal for the repointing. With winter and lots of rains coming, carpe diem!

fernicarry
Posts: 123
Joined: Fri 22nd Jan, 2016 11:10 am
Location: Argyllshire

Re: Pointing sandstone

Post by fernicarry » Mon 5th Oct, 2020 2:15 pm

Thanks both. Lime Green looks good, I can handle a paddle mixer.

Do you think I should go for 'strong' since the joints are upward facing?

Feltwell
Posts: 5627
Joined: Sun 18th May, 2008 7:28 pm
Location: Shropshire, England

Re: Pointing sandstone

Post by Feltwell » Mon 5th Oct, 2020 2:18 pm

Probably a good idea - it'll be more resilient in an exposed position.

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