flagging patio without hardcore

[88stevo]

hi,

i was wondering if it is possible to flag a small area 16ft x 12ft using 2x2 concrete flags without using a hardcore base, the bed consists of stones/mud/clay, seems pretty firm lots of stones and gravel in it. so would it be possible to just lay a 10:1 sand/cement mix over the bed and then lay the flags on them.

is this the best ratio to use? semidry mix? what would the best depth of the sand/cement for this type of lay.

thanks.

 

[PrenticeBoyofDerry]

Have flick down this link it will help you chose a suitable sub-base.
http://www.pavingexpert.com/patio01.htm

 

[WabbitPoo]

Bit hard to say without seeing it, but yes you CAN lay without a hardcore base. Use a mix of 2 sharp 2soft and 1 cement, mixed fairly wet. Fine for foot traffic is the soil/stones you describe is not prone to swelling in wet weather. Just remove any soft loamy patches and fill with some crushed stone.

 

[Carlnorwich]

Wabbitpoo.

When you say no need for a sub-base if it is only for foot traffic.

I put a small patio down for the out laws, before I started we had an argument because I insisted on a compacted MOT Type1 sub base; 75mm. He wasn't happy because he said it didn't need a sub-base.

After it had been down a couple of months they bought themselves a swinging chair and sat it on the patio. The pair of them (combined weight of about 35 stone) both sit there swinging backwards and forwards with the weight being transfered through the 4 posts of the swing, and therefore concentrated onto 4 individual slabs.

If I hadn't have used a suitable sub-base then surely the patio will now have moved - wouldn't it?

 

[WabbitPoo]

nope i doubt it would. think about it: the mortar bed and all those slabs make one big "concretey" raft sitting on the "soil" so the fact that one slab takes such a gigantic load (they wanna think about losing some) doesnt matter. thats why a strong bed is good.

 

[Carlnorwich]

Thanks WabbitPoo, just to clarify;

So if the ground feels solid then don't bother with a sub-base?

My back garden is clay and is prone to waterlog - so I would definately need a good sub-base?

Thanks.

 

[WabbitPoo]

Thanks WabbitPoo, just to clarify;

So if the ground feels solid then don't bother with a sub-base?

My back garden is clay and is prone to waterlog - so I would definately need a good sub-base?

Thanks.

Yes you would because as it shrinks in summer you will get voids which could lead to problems, plus possibly the opposite when really wet.