Gravel base for concrete slabs

[marcus25]

Hello,

At the foot of our garden the water collects and very slowly drains away which causes it to be very muddy pretty much all of the time, so we are going to put down 3'x2' concrete slabs in this area. we are going to dig out the top layer of grass and soil down a few inches, would 10mm gravel be a suitable base to put the concrete slabs down onto and the gravel to be directly on top of the soil underneath? just so the water can still collect and drain away under the slabs.

 

[r896neo]

Gravel is fine as a sub-base providing its compacted well. If you do use gravel it needs to be restrained on all sides to stop it spreading.

You would also need to lay the slabs on mortar as sand would simply drain away.

 

[marcus25]

spent the last few hours digging out the grass, under the grass is mostly stones and not quite soil but a thick mud anyway. All the water was being collected by the grass itself, underneath is fine so seems to be the grass which is the problem, we've put down plenty of 10mm gravel, compacted it and it is restrained on all sides by existing slabs on 2 sides then the grass on the remaining 2 sides, need to get a still saw tomorrow to cut about 2 inches off of 2 slabs as when the house was built there is an odd size slab in place which will put everything off. there is plenty of adjustment going on while laying, making sure they're level and in line with the rest of the slabs by putting extra gravel under the sides that need lifted a bit. But so far so good though considering i've never tackled anything like this before, got 5 slabs down, 7 to do tomorrow but got a couple of mates coming to help. today was just me and my fiancee doing it!

here it is after todays work

where the gap is in the middle thats the one thats a couple of inches short.

From the slab closest to the bottom of the picture on the left hand side its still to come out another 2' so a little more grass to come out.

later on when we get more slabs will be extending it off to the right of the photo

 

[r896neo]

Hi sorry to teach you to suck eggs if you were already doing it but you can't lay the slabs on just gravel, a sub-base of gravel is fine but they need to be layed on mortar or the pointing will endlessly crack due to the subtle movement

 

[marcus25]

Hi sorry to teach you to suck eggs if you were already doing it but you can't lay the slabs on just gravel, a sub-base of gravel is fine but they need to be layed on mortar or the pointing will endlessly crack due to the subtle movement

there will be no pointing in between the slabs to allow for drainage, they've all got gaps of around 5mm around all of the slabs and will be putting for very fine gravel in between, just for drainage as this part of the garden is at the bottom of a slope so all water drains down to that part of the garden, hence it being a bog all of the time, it is only for very light use, dog spends more time out there than we do! Even the existing slabs that are there that the house builder put down aren't on a bed of mortar or sand, no pointing, just on gravel directly over the various stones and mud and haven't moved in over the year it has been built. We're just following the same method they've used.

 

[r896neo]

Ok, if your not pointing it then it'll be no problem. Good on you for perservering get a flag level on a gravel base will take a good few goes i'm sure!