hardcore base for patio.

[Mattayscough]

HI.

I am about to start to construct a patio. I am going to lay sandstone paving and the soil in my garden is clay. Therefore, I have worked out that I probably need a compacted hardcore base of 75mm and then 75 mm of compacted sand and then a couple of inches of morter to bed my slabs onto.

Firstly, does this sound ok?

Also, how small do I need to smash the hardcore? I have plenty of concrete and brick rubble, but I have no idea how small I will need to break the peices into to get a stable base. Does anyone have any ideas about this?

my pation will be 3m X 3m (9 m2). Is it possible to compact this by hand (well ground rammer) or is it wise to hire a plate vibrator?

Thanks, any healp would be greatly appretiated.

Matt

 

[Thermo]

firstly a sand base under a sandstone patio will be no ggod. You need to use a layer of mot type 1 crushed stone, a minimum of 50mm thick. crush the hardcore down as small as you can, smaller the better. A vibrating compactor will be best, although you can do it by hand. the mot will go pretty solid once crushed down and give you a decent sound surface to mortar the sandston on.

 

[Mattayscough]

mot type 1 crushed stone, a minimum of 50mm thick.

Is this what is refered to as 'hardcore' or is it a seperate layer?

DoI then put the morter directly onto the hardcore layer and lay the slabs?

Sorry- this is my first patio!!

Cheers

Matt

 

[Mattayscough]

Can I use concrete and brick rubble lying around my garden for the hardcore as I have loads of this (and I am trying to gert rid of it)?

 

[noseall]

yes, you can lay the mortar directly onto the mot hard core layer. the beauty about mot, is it compacts to a very stable surface. no need for any sand blinding.

 

[Mattayscough]

ok slabs mortared onto the hardcore it is.

Why do the diy books say to put a compacted layer of sand onth the hardcore base?
Any ideas?

Matt

 

[Thermo]

no no no.

put the layer of hardcore down, ie the smashed bricks first. Get them fairly small.

now put the mot on top of them then compact it.

now lay the slabs on mortar on top of them.

some slabs can be laid on a compacted sharp sand bed, but not sandstone.

clear?

 

[Mattayscough]

Any ideas on cost for mot type 1 for a 3x3 meter patio assuming that I am going to lay a layer of smashed brick/concrete first? How deep should either layer be?

Thanks again for your help.

 

[Thermo]

depth of hardcore doesnt matter too much, depends how much you want to get rid of. Its only for foot traffic so its not essential. Allow about 100mm-150mm for it. 50mm of mot on top of that (comapcted thickness) will be more than enough. A bulk bag from a builders merchant should be enough. Should be in the range of £35-£45 inc vat.
its easy to use and shovel. you can spread it with the shovel or a rake and get it roughly level, before compacting it. gives a nice firm smooth surface to lay the paving on. A vibrating plate compacter should only be about 30 for the day or about 40 for a weekend (it will do the job in about 10 minutes!)

youre more than welcome, nice to get a thanks!