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Posted: Tue Apr 29, 2008 3:19 pm
by Phil D
Hi
Great site; I am after a bit of advice as I am having a large patio layed within the next couple of weeks (approx 56m2) and I have already done some prepartion by laying down a membrane and then putting approx 100mm of crushed concrete on the top as a subbase. My contractor will complete the rest of the job and is proposing wack down the subbase & then to lay the slabs on top of approx 40mm of glass sand, he is then going to fill in the gaps using dry kiln sand.
I am a little worried after reading lots of info on this excellent site as most of the patio's seem to be layed on a motar mix and then pointed in between the slabs. Do you think my contractors method is suitable? I am planning to use bradstone old riven flags in a random pattern, what gap should be left in between each flag?
Many thanks for any help & comments - Phil
Posted: Tue Apr 29, 2008 4:42 pm
by Rich H
If that's what he's proposing then consider changing your contractor.
These slabs can be laid on a screed as they are a uniform thickness but I've found that this is for a given value of 'uniform'. You'd be better off laying them individually. Either way, a sharp sand and cement mix is required. Secondly, they will need to be jointed properly. The joint size as I recall for these slabs is 10mm (worth checking with Bradstone). If the joint size isn't right, the pattern won't work. 10mm is much too big for kiln dried sand - at that size the jointing ought to be part of the structure of the paving. Either a good quality polymeric or mortar will be ok.
Posted: Tue Apr 29, 2008 4:51 pm
by Phil D
Hi Rich
Thanks, can you recommend a good polymeric as the one I had a look at earlier by Romex seems very difficult to get hold of. - Phil
Posted: Tue Apr 29, 2008 4:58 pm
by Rich H
Posted: Tue Apr 29, 2008 6:10 pm
by lutonlagerlout
what is the membrane for?
are you trying to retain water in the patio??
terram or multitrack yes,membrane no
laying on glass sand is a total bodge ,must have cement in it
as for the kiln dried there are 2 schools of thought on this==> mine and the rest
i did a patio a few years ago for a polish guy,anyway he was short of money so he said he would point it
i went back to do another patio last year and he had brushed KD sand into the joints
he says every spring he jet washes it ,then applies new kd sand and it looks great for 1 summer,which he is happy with etc etc
as i lay on a wet strongish mix, no slabs have moved,the fella is happy and it looks nice every summer
but ,big but pointing is recommended
regards LLL 
Posted: Tue Apr 29, 2008 9:01 pm
by J.D
You have read the site done the preparation. why not finish the job yourself (on a motar bed and pointed ) and save your self a few quid ? If not and you decide to pay get it done right !
Posted: Wed Apr 30, 2008 12:01 pm
by Phil D
Hi Guys
Thanks for the comments, what are the major issues with laying on Glass sand? The guy's laying the patio work for a ground works company and assure me that that this is a very provern method....Would they be telling me this, because it is quicker to lay a patio this way??? ???
Posted: Wed Apr 30, 2008 1:27 pm
by Rich H
Yes, much - mainly because there is no mixing to do.
The sand will become unevenly fluid in time, worms will work their way in, mix in soil, the pointing will crack, etc. etc.
I can't think of anyone I know in the trade who would advocate this approach for your application.
Posted: Thu May 01, 2008 12:11 am
by matt h
read main site, all has been laid out in great detail. avoid glass sand likethe plague:(