Should I lay my Patio on a concrete mix or sand?

[alec_robertson]

I am about to lay a Patio in my Garden; my original plan was to lay the patio on a hardcore and sand base. Although I have been advised by a friend to lay the patio on a hardcore and concrete base, is this necessary? Also should I point between each slab or just lay each slab ‘hard to’ the adjacent slab? The paving is a mixture of 600x600, 600x300 and 300x300.

[thedoctor]

The best base is a mix of sharp sand and cement mixed at 8 to 1 Alec. This gives a firm but fairly flexible base which will not wash away from under the slabs when heavy rainfall is running down the garden. It should be about 50mm thick and mixed fairly dry so you can squeeze a handful and it will stay in one lump but no water will come out. See our project for pointing a patio. There should always be a joint as 99.9% of the time the slabs are never exactly the same size. Trying to butt them up leads to joints going out of line and looking horrid. A joint of about 20mm gives a lot of leeway, looks good and can be jointed properly to stop water getting into the joints.

[alec_robertson]

Many thanks for your reply, which will be most helpful. Is it preferable to fill the joints with mortar or can I use an alternative i.e. sand and cement dry mix, sand only or gravel etc.

Much obliged

Alec

[ChrisGrocott]

I am also interested in this. The original joints failed in my patio and following advice I have twice tried to refill them with a 1:1 sand/cement mix but it appears to be too sandy and washes out. I then tried 100% mortar which mostly holds (bar a few places) so I am about to do the lot with mortar in attempt to get joints that will last for a few years at least. Is this the correct thing to do ?

Chris