The Brew Cabin

Posted: **Thu May 29, 2008 11:17 am**

Morning All,

I am part way through laying a patio of Purestone flags where I have dug out and levelled 30sq m to 6". I have a drop of 6mm/m and I will be laying MOT to 100mm compacted to 75mm followed by a moist mortar mix to lay the slabs on (thanks to this site

)

Now, with all the weather we have and having backfilled (compacted at 6" intervals) a trench for SWA to the garage I have areas of "soft" ground. And in one area of 600mm sq I have something resembling a bog (as the trench was left open as it started chucking it down.....and being an ex-hard northerner turned soft southerner I thought it was time to go in).

I suppose my questions are:
1) Do I need to wait for the ground to dry/settle/harden?

2) Will throwing a tarp over the affected area help/speed up the settling?

3) Would whacking it help?

4) Generally after levelling the mud is loose (well, it is when I do it due to the raking) - does it just require walking over before adding the subbase and whacking it?

At the minute I'm on hold and hoping the weather will turn.....fingers crossed.

Ian

Posted: **Thu May 29, 2008 5:06 pm**

Best to let it dry out a bit. Sometimes you can put the MOT down, compact it, and still feel it give because the ground underneath has become fluid. If this is the case you should leave it.

BTW, 6mm/m fall is not really enough for most paving. 1:70 (roughyl 15mm) is preferable if possible on the site.

Posted: **Fri May 30, 2008 9:52 am**

I guess I knew the answer but thanks.

With regards to increasing the drop to 1:70 - as the patio is 6m long - would it be ok to raise the far end by using more MOT to raise it by 9cm (for the 1:70)? I will try shifting some soil but as most of the area has been excavated I seem to have nearly run out of soil. WHat I'm asking is - will there be any issues with having the MOT compacted 75mm at one end and 160mm at the other (besides the cost!)

Posted: **Fri May 30, 2008 5:05 pm**

No, as long as you're ok as regards the DPC with any adjacent building and you compact the MOT in layers of not greater than 100mm. You can lay with a lesser fall but expect considerably greater maintenance and a shorter life for the pointing.

Posted: **Fri May 30, 2008 10:00 pm**

Thanks again.

The only building close by is the garage (which the patio butts against) and it is the garage's DPC which I'm using as the datum point and the drive drain is situated approx 170mm below the DPC. I would have prefered to slope away from the DPC but the garden slopes up away from the garage.

Seems like I'm going to have to get another delivery of MOT then.

Cheers

Ian

Posted: **Sat May 31, 2008 1:23 am**

better to have a good base than to have to sort it out later;)

The Brew Cabin

Wet ground - Is it ok to lay flags on wet ground.....