The Brew Cabin

Posted: **Sat Feb 24, 2018 9:46 pm**

I've got a 10cm sub base made up of compacted hardcore from a demolition job in the same garden (smaller than quarter bricks) and sharp sand. In order to get the flattest finish with the whacker the top 2cm is sharp sand only.

Given that this is compacted well would it be ok to lay the 5cm wet mortar mix directly onto this sharp sand with the 20mm slabs on top? Or should I look to mix in some cement into this top later before the mortar mix?

Thanks

Posted: **Sun Feb 25, 2018 11:23 am**

Sand can't be a sub-base: it doesn't provide sufficient interlock and stability. It is acting as a fill layer, and, unless it's fully restrained at all edges, it runs the risk of moving and causing settlemnt in your rigid bed and paving layer.

For this reason alone, I'd look to stabilise it by mixing through a minimal amount of cement, say 12:1 or even 20:1. The aim is, as I said, to stabilise rather than build a hard structural; layer.

The Brew Cabin

Sharp sand as sub base