Have I bought the wrong sub-base material?

lintdrummer

Hi everyone.

Plenty of time on my hands at the moment so I'm making the most of it with a couple of projects on the go.

I am extending our driveway into part of the front garden so both cars can be off the road. The driveway is cobbled but the extension of it will be compacted loose stone.

The second project is a paved patio area in the back garden using sandstone slabs.

So both of these require a sub base material. I ordered 4 tonnes of 14mm pea gravel. After further reading online I now think that this is not suitable as a sub-base material. Should I try and get the stone exchanged for something more suitable or is it possible to use it anyway?

For what it's worth, I'll be using gravel stabilising tiles on top of the sub-base on the driveway and these will be filled with the decorative stone.

The patio sub-base will either be topped with paving sand or mortar, I haven't decided yet. Opinions welcome, the patio is not beside the house if that matters, it's in the garden.

10-10-20

Pea-gravel isn't what you need, sorry to say. You need a crushed stone called 803 as the sub-base on the slabs, and 803 might also work with the drive-way, but it won't be ideal or pretty.
The crushed stone is used as it compacts as it's full of rough and uneven edges with a mixture of size right down to fines. See this link for more details:
https://www.pavingexpert.com/subbase
Directly under the slabs you need paving sand, a washed irregular fine stone. This allows the slabs to bed-in and prevents the sand from being washed out in heavy rain.

Lumen

Considers SUDS.

10-10-20

Ah, found what I was looking for:
https://www.pavingexpert.com/layflag1
AJ knows his paving.

lintdrummer

10-10-20 wrote: »

Pea-gravel isn't what you need, sorry to say. You need a crushed stone called 803 as the sub-base on the slabs, and 803 might also work with the drive-way, but it won't be ideal or pretty.
The crushed stone is used as it compacts as it's full of rough and uneven edges with a mixture of size right down to fines. See this link for more details:
https://www.pavingexpert.com/subbase
Directly under the slabs you need paving sand, a washed irregular fine stone. This allows the slabs to bed-in and prevents the sand from being washed out in heavy rain.

Thanks for that informative reply. Yes, the supplier I got the pea gravel from also stocks the 803 for the same price so hopefully he'll be open to the idea of an exchange as I'll be purchasing the paving sand from him too.
I had been browsing that paving expert site today which is what lead me to question the pea gravel. It's a great resource.
Do you have any experience with paving sand? This is for large sandstone flags and I obviously want them to be as solid as possible. I'd rather use a mortar bed if it's going to give a better result but obviously it would involve a lot more work.

lintdrummer

To answer my own question: after another look at the paving expert website it looks like a mortar bed is the only good choice for large sandstone slabs.

keithdub

If the company do rentals get a wacker plate if you cant dont lay the slabs down