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Posted: Thu Sep 09, 2004 10:32 am
by Sull
I have now laid all the whole slabs and large cuts on my path and have a few problem areas to sort out.
1)There is a round inspection chamber in the middle of the path which I have cut the slabs about 50mm away from the rim, which latter will be buried in concrete. The edge of the lid at the moment is 5 mm low at one end and 15 mm high at the other end. Is it OK to cut the top of the plastic inspection chamber away to allow the lid to lie flush with the paving or should I ramp up the concrete? There will be 75mm of concrete between the visible part of the rim and the paving.
2) What is the minimum width I should cut a 40mm riven slab when paving around obstacles. (The bedding layer is sand if that has any relevance) Where I revert to in situ concrete, should it extend down to the sub base?
Posted: Thu Sep 09, 2004 8:51 pm
by 84-1093879891
Yes - cut down the plastic chamber to ensure the lid fits flush or slightly below the paving level (3-6mm, no more). Use a strong concrete mix to form the infill - we like to use a granolithic mortar, but it's not available in all parts of the country.
When it comes to cutting flags, the usual guidance is that no piece less than a quarter of a full flag should be used - so, if you were using 450x450mm flags, then nowt less than 225x225mm. However, I feel that this can be eased slightly when strips of flagstone are needed, and I'm happy to see strips of 150mm length, as long as they are a full unit wide and laid on a full mortar bed. So, with 450x450mm flags, I'd accept a strip that was 450x150mm, but if it was to be 450x100mm, I'd rather use inboard cutting or cut down two flags to accommodate.
When using infill concrete, it should really extend the full depth of the paving and the bedding layer, to the sub-base, if one is present. And it should not be more than 75mm wide - I'd prefer a maximum of 50mm wide, but this is not always possible.
Posted: Fri Sep 10, 2004 11:44 am
by Sull
Thanks for that. Your answer has raised another question though. I was originally going to have copncrete down each side of the path were it abiuts the garden wall and the house, but quickly decided that the gap was too wide. Unfortunately I didn't rethink the positioning of the slabs. They are centered on the path which looks very nice but means twice as many cuts. These cut pieces are about 175 wide and I was planning to bed them on sand, the same as the rest of the slabs. Will this be OK as they are unlikely to get much foot traffic being against the walls?
Posted: Fri Sep 10, 2004 12:28 pm
by 84-1093879891
They should be fine bedded onto grit sand, but it's actually easier to bed them onto a wettish-mortar or the semi-dry bedding mix (10:1) to which I constantly refer. Getting consolidation to refusal with a 175mm strip of flag is tricky - there's a real risk that the pieces will snap before reaching refusal, so a cement-bound bedding material is more forgiving.
Posted: Fri Sep 10, 2004 1:05 pm
by Sull
Thanks for the quick reply. Ill have a go with the sand and if find I keep breaking 'em. I'll switch to mortar.