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Posted: Wed Jun 17, 2015 10:49 pm
by Ouch
planning on an edge course (to lawn or gravel) and mowing strips of stone setts around a flagged patio, should I be using a mortar or concrete to secure it?
The pages on the website covering block paving which describes edge courses in detail suggests concrete, however the flags & slabs page suggests a class 2 mortar.
If I use concrete - what size aggregate? 10mm 20mm?
There's about 50 linear metres of edge course in total on this project, so I'd kinda like to get it right 
Posted: Thu Jun 18, 2015 7:05 pm
by sy76uk
It depends how thick the setts are to a certain extent.
If the setts are 20mm thick for a mow strip then 75 mm of concrete with 20mm of mortar for bedding.
If the stats are 40mm plus then bed straight on 100mm of concrete if it's lean mix use a cement slurry to bond.
For a patio border either do as above to set levels and string lines off the top to lay paving or lay the flags first and sets as yo go or after.
Posted: Mon Jun 29, 2015 7:15 am
by Ouch
Sorry I missed your reply..
I'm intending to lag the edge course first, and the setts will probably be 50 mm thick or so (looking at granite or snadstone, the missus can't decide) and 200x100. This way i can use the edge course to help set the levels
I'm guessing the mortar on concrete is a 2 hit affair: put down concrete, let cure, mortar setts on top? Would the slurry be a simple wet cement mix, or is there something else in it?
Posted: Mon Jun 29, 2015 10:13 pm
by lutonlagerlout
the best way is to bed the setts straight into the (dryish ) concrete and then haunch with wetter stuff
I have done this many times and it works
LLL
Posted: Tue Jun 30, 2015 7:46 am
by Ouch
Thanks LLL - that sounds fairly sensible. Given the size of the blocks, would 20mm aggregate be too big?
Posted: Tue Jun 30, 2015 10:01 am
by Tony McC
10mm aggregate - see this page and video
Posted: Tue Jun 30, 2015 11:46 am
by Ouch
Thanks Tony - I (re)discovered that video this morning and will be calling my tame builders merchant this afternoon when I get some quiet in the office..