Are patio slabs ok straight on to sharp sand?

[Penelopejean]

Hello All,

I've been on pavingexpert.com as advised in several posts here which tells me that sharp grit type sand (not building sand)is an accepted way of laying slabs for a patio. I've looked at several forum questions and most of you say that this method is NOT good.

The soil is clay and very dense. My landscaper says he will lay the 2"thk 2ft square slabs straight onto sharp sand onto the soil. Not sure how thick unfortunately.
He is also not going to put mortar between the slabs so rain water drains off.

There will only be light non vehicle traffic.
What is correct from experience to all out there please?

Thanks
Penny

Read more: //www.diynot.com/diy/threads/is-sharp-sand-ok-for-laying-a-patio-in-back-garden.451832/#ixzz3yHiZNTDo

 

[wrathkeg]

The Paving Expert page on bedding materials (http://www.pavingexpert.com/layflag3.htm) recommends a sand bed for units smaller than the ones you are planning. I would go with a 10:1 sand cement mix. Your landscaper could have lots of reasons for suggesting laying on sand only, and leaving open joints. It would certainly make the job much easier.

 

[wrathkeg]

Also with the right fall on the paving there should be no problem with drainage. Make sure it drains to a sensible place (i.e. not towards your house).

 

[Penelopejean]

He's going to put some cement on top of the sand too he says, which I'm glad about. he's talked about the fall away from the building so all's well so far. Thanks for the advice.

 

[r896neo]

Laid like that I would give them about 8 months before they start rocking, no wonder he wants to leave the joints open as pointing wouldn't last more than 6 months.

Regardless of the sand vs sand and cement mix debate you need a sub base of at least a couple of inches. Most professionals lay paving to the spec of 75-100mm compacted sub base for patios.

Consider the massive disparity between the top spec approach of

dig out whole area to 185mm depth
100mm sub base
30-50mm sand and cementy bedding
Flags pointed with mortar (weed free)

Lasts for 20 years plus

vs

dig out area to 85mm

flags laid on sand

let the weeds be the pointing

Lasts for a couple of years before its all over the place.

I would guess your 'landscaper' gets back on his horse. Pay peanuts get monkeys

 

[r896neo]

hes going to put cement on top of the sand????

Major alarm bells here the guy has no clue what he is doing

 

[WabbitPoo]

Preferably a 4" base of compacted roadstone then slabs laid on a full wet mortar bed

or you can omit the base if the soil is very solid.

As has been said, what he is proposing WILL FAIL