Crazy Paving sub-base design

[Andrew in Melb]

Hi,

I couldn't quite work this out from the site, so looking for advice! I'm laying Crazy paving for my backyard, only foot traffic, NO vehicles. 80sqm. On a mostly-clay soil, with pretty bad drainage. Pavers are Monaro stone, 16-25mm thick (http://www.norstone.com.au).

The paving supplier said I 'needed' a concrete sub-base, but I'm not sure about this. Could I use an unbound sub-base? How thick should it be?

Also, the yard is pretty cut-up at the moment (newly built house); should I get it levelled out before I look at laying the sub-base?

Appreciate answers to these questions, and any extra tips! Thanks.

[84-1093879891]

My understanding is that frost heave is not a problem in most of Australia, so a concrete sub-base could only be for strngth, not frost protection.

I'm not familiar with these pavers, but at only 16-25mm thck )or 16-25mm thin, I'd say) they sound more like tiles than pavers, anbd as such, they really would need a concrete or other firm, bound sub-base/base to give them proper support....I've just had a look at the site you mention and I reckon they are Indian sandstone, what we would call 'flagstones'.

I reckon you could lay these on a bedding layer of cement-bound material, say the 10:1 mix of bedding sand and cement that I keep mentioning. This should be 35-50mm thick and laid over a firm sub-base or base. If this was an area that would be trafficked by any vehicles, then I would definitely suggest the full concrete bed/sub-base, but for a foot-traffic patio, the 10:1 mix should be fine.

As the area is a bit of a mess at the moment, it is better to get it levelled out and compacted before placing your sub-base material, which should be at least 100mm thick.

[Andrew in Melb]

Thanks - this will help. I've decided to look for alternate paving anyway; this stuff was quite thin, and expensive. I've found Bluestone paving for only $20sqm (about 8 pound sqm), which also comes much thicker (40mm).

cheers,
Andrew