Depth of base

[Turky]

I started my patio with yorkstone imitations 300x300, 600X300, 600x600 ran out of sub- base, and have plenty of grit sand making up to 150mm thick will this be ok, 10:1 mix. It a apears solid kids and wife extra all over it. not pointed yet and half wsy through with 3 days to go, should I take up and put more sub-base down now that builders merchants are open.

[ken]

yes, take it up. In time it will slump, even with cement in it at that depth. take your time and get it rite first time.

[Turky]

Thanks Ken

Thats not the answer I wanted, whats the maxium depth I could use grit sand sand and could I add more cement.

[ken]

35-50mm is what id use. even with more cement in, i rec it will still be "a bit dodgey" im sure it will all be explained in full some where on tonys site.

[84-1093879891]

Ken's right - any sand bed more than 50mm thick will drift and your paving will go with it. It won't be this week, or next week, but after we've had a week of miserable rain, and the ground is saturated, that's when it will go.

The only way out is to replace the additional thickness with a stable material - ideally, this would be a granular sub-base material, such as DTp1, scalpings or crusher run, but if you must use up the sand, it needs to be mixed as a concrete, what we call a 'lean mix', which would be 5 parts gravel or other coarse aggregate, 5 parts sand and 1 part cement, all mixed up with water, placed and compacted before continuing with the patio project.

It's actually cheaper to use just a granular sub-base than to eff about with all that lean mix, and it's a lot less work, as there's no need to 'mix' the sub-base material! :)