Patio advice

[baldersj]

Evening...
having started digging my lawn up to lay a patio, I've found that as well as being as tough as old boots its also laid on good old London clay. Does this mean I should dig a bit more (I'm already digging down about 300mm) and put a layer of hardcore down to help with the drainage?

Is it enough to just lay the HC or does it need whacking? I then intend to put down a layer of sharp sand followed by the slabs, and brush a sand/cement mix into the cracks. Does this sound about right? Sorry if its a bit basic , but I've never done it before and I don't want the missus blaming me when we end up with an unplanned pond in the middle of the garden!

 

[Thermo]

put down mot type 1/scalpings/roadstone as a base layer and compact that with a whacker plate. You can lay slabs on a compacted sharp sand bed, however you will get a better long term result if you lay them on a mortar bed. If you are going to lay them on sharp sand make sure you have those at the edge mortared down to create a frame to hold the rest in place.

Point them up properly, dont just brush it in. Use a 1:3 or 1:4 mix of cement and sand and make it just damp enough that you can mould it into a ball in your hand without any sticking to your hand. Trowel that into the joints with a pointing trowel.

Why are you digging down 300mm?

 

[baldersj]

Cheers Thermo, is 300mm too much then? Hope it is...
I was told 200mm of MOT, followed by 50-60mm of S/C, then the slab. I'll be quite happy to dig less...just out of interest, what quantities of sand/hardcore are we talking about for a 27m/sq area?

 

[Thermo]

is it only for foot traffic?

what type of slabs are they?

 

[baldersj]

Yes, back garden, v. small.
They are riven concrete 450x450 bog standard slabs. According to the spec they can be either solid bedded or laid on sand.

 

[Thermo]

if you are using mot then a minimum bed of 75mm (compacted )for the mot and 50mm for the bedding material will be ok. you will get a better long lasting result with bedding them in mortar.

 

[baldersj]

Cheers. Enjoy the weekend