Patio subbase depth

MarinaTrench

Hi, 
I'm getting a new sandstone patio installed in back garden. 
My landscape gardener tells me that a subbase of 5 cm type 1 mot followed by 3 cm of concrete and slabs on top is sufficient. 

Is this correct? Online paving vendor websites suggest that it should be 10 cm subbase.
Thanks
Marina 

ac198179

I thought it was meant to be 10cm subbase and then 5cm of mortar?

TELLIT01

I can't help on the required depths although the subbase was definitely more than 5 cm when we had our patio done.  What you do need to check with the landscaper is how when intend to do the mortar holding the slabs.  For sandstone it needs to be a solid layer, not the 5 blob method often used for concrete slabs.  Blobs of mortar will show through eventually as circular discolouration.

stuart45

It should be a full bed for any slabs to avoid any voids in the mortar bed.
100mm is standard for the sub base.

FreeBear

My go-to guide is https://www.pavingexpert.com/

Recommended sub-base depth for a patio is 75-100mm - I'd go 100mm as a minimum and ensure it is well compacted with a whacker plate.

TELLIT01

stuart45 said:

It should be a full bed for any slabs to avoid any voids in the mortar bed.
100mm is standard for the sub base.

I'm not disputing that it should be a full bed, but I've lost count of the number of times I've seen photo's on gardening forums asking why their lovely Indian sandstone slabs have discoloured areas.  Always caused by the people laying the slabs using the '5 dollops of mortar' method.