New patio - compacting subbase

[str]

In the process of building a patio, retained on 3 sides by stone garden Walls and on the 4th side by a new retaining wall.

Currently building up to the right levels with my sub base, some type 1, which I intend to compact with a vibro plate.

Question is, how much should I expect the sub base to drop once it's compacted?

Also, intend to lay the flags on a dry mix of grit sand and cement - is this an accepted method? Have researched but there is a lot of differing views!

 

[imamartian]

I'm only a DIYer, but i don't think you really lose any depth. Loose subbase has peaks and troughs, whacking down just really evens it out at the low end of those peaks and troughs.

As for dry sand and cement, i wouldn't, but many would... hence the mixed opinion... if you're not regularly parking a hummer on it... you'll be fine.

 

[str]

it is just for foot traffic, table and chair and the kids to play on, so no vehicles.

if you wouldnt use a dry mix, what would you use?

have been looking at pavingexpert, which seems to be a good source of info, but even then, they still suggest differing methods?!

what to do a proper jub first time off!

 

[RedHerring2]

It's normal, IIRC, to lose about 10% of depth of subbase with whacking.

I wouldn't use a dry mix either. I find a wet mix easier to lay.

 

[r896neo]

It all depends on the size and material the flags are made from. As i general rule I lay concrete flags (wet cast or pressed) under 450x450mm on grit sand and any larger or mixed larger sizes on mortar.

All natural stone should be layed on mortar.

 

[J_N30]

Ive been looking at the bags of premixed and it says lay dry and covers 4x 450x450mm slabs.

Do you think this is ok? How does it work, will it set eventually?

 

[r896neo]

Yes in will set but not in a conventional sense like a brick laying mortar. It will form a solid bound mass but it will remain pretty crumbly if you hit it with a pickaxe etc you would go well into it. But it forms a perfect bedding material for flags like yours. but don't point with a dry mix it will end in tears in a matter of months.

Make sure to lay any flags with a free edge onto wet mortar though

 

[str]

was plannig to use indian sandstone, with a mixture of sizes, the largest being 560 x 700.

if i use a wet mix, what mix and consistency should I be mixing to? also, do i use builders sand?

 

[r896neo]

indian sandstone definately needs a full wet mortar bed. I use plastering sand as building sand can get a bit wet and messy when flags are being tapped down.

It should be about the same consistancy as for bricklaying