Patio preparation

[Smileysmile]

Hi guys,

Really need some help here. In the photo I have uploaded I have removed 6 inches of clay like soil with a very mouldy weed membrane on top then chippings. As you can see in the photo a square section has been dug. This is where I intend to put a small shed. The ground is now hard. Does this look deep enough? Although water takes time to soak in. Am I right in saying lay down some weed membrane then some aggregate then a layer of wet sand then a couple of slabs for the shed to rest on which will be about 5 foot wide and just under 3ft deep. I intend to dig up the rest of the area eventually but want to get a shed to hold garden tools. You can see the one slab still in place to give you an idea the depth from the top of the slab to the bottom. I intend to put aggregate down, level it off and then crazy stone with pea gravel in between. Is this right? Look forward to some feedback. Thanks

 

[Ian H]

You could bed the slabs directly into sand cement mix and give them a very slight fall so water runs off into that gully rather than having to soak away.

 

[r896neo]

If its only for a shed id follow ians advice. Lay them on a generous 50mm bed of 6:1 grit sand : Cement. If you need to raise the height because you've dug it off then a few inches of compacted sub base would be great.

 

[Smileysmile]

It's only temporary until I've prepped the whole area and decide if I am going to flag stone or proper patio slabs the whole area. Basically prepping (removing the existing clayish soil down to hard ground. Looking at the photos guys have I got to the foundation of where I need to be before adding aggregate/tamper/membrane/stones etc? To cap: The prepped area you see in the photos I can lay gravel down, spread it level in that area to the appropriate depth which eventually I would do for the rest of the area, then temporarily lay down a slab or base to hold a 5ft wide 3ft depth shed to hold tools. Don't want to cement the slab down. Just wondering if a membrane goes down first before the aggregate? Ps what gully? Do you think water will stand on the aggregate? Thanks for the responses btw

 

[Ian H]

Water will pass through the aggregate but it's very close to the house. By gully I mean the orange thing with black grate that your kitchen pipe runs into.

 

[r896neo]

Unless your working with made up or bad ground, you generally decide how thick a sub base you want, how much bedding layer and the thickness of your paving and then dig down to that depth. The only time you would alter this formula is if the groun appeared unusually soft or had lots of rubbish in it implying it is not original earth but loose fill as is often the case with new builds.

A geotextile membrane can be used under sub base to prevent the sub base mixing with a soft or damp clay sub grade but its not needed on 95% of jobs.

The usually make up for patio would be 75-100mm of compacted sub base, 30-50mm of bedding Depending on type of paving and then flags or blocks from 25mm-50mm thick.

You want to use sub base such as MOT type 1 rather than gravel or aggregate of any kind. You can simply plonk a flag under each corner of your shed on top of this as a temporary measure.

As for water type 1 is permeable and will not pond water unless the underlying ground is very dense clay. Basically if water ponds on it now without the sub base it will continue to.

 

[Smileysmile]

Thanks for all the response. I am still looking at sheds to fit the gap. http://www.shedstore.co.uk/garden-s...=product_ads&gclid=CIyspZbcutMCFclsGwodMkoH6g which is a perfect fit yet still unsure about the colour and being more used to a wooden shed but I can't find the right size and quality. So a good level is needed as these sheds don't come with a base as they are bolted to the concrete or slabs. But this particular metal shed was voted #1 with whatshed.

r896neo, the underlying ground is solid. But I don't know what it consists of as the house was built in 2001, I moved in 2007 and as far I know the garden area hasn't been touched so the developers could have left a mess ie clay. So I am a tad concerned whether I should did a little deeper if water is not sinking through easily. Any suggestions to what I should do? I am still looking on the internet to be sure of right shed but the the green metal one is so far #1. I need to get the mower, strimmer etc out of my kitchen asap. I am going to order some MOT1 sub base soon to level this area off, with a couple of heavy paving slabs to anchor the shed down to. Shame I can't get just the one slab but I doubt their is one this size. When I have the shed down I will probably start on digging up the remaining of the patio area of the 6 inch clay, mouldy membrane and gravel. But I am not sure if I am in the position to lay a patio or flag stones down quite yet as I can't decide which I want and if I have the funds. Thanks in advance.

 

[r896neo]

Hey, not sure if there is a question in there or just your thoughts. If there is something could you edit it a bit?

 

[Smileysmile]

Yes do you agree with my preparation? Do you think the ground is permeable? Or do you think I should excavate a little more?

 

[r896neo]

2001 is plenty of time for ut to have settled so don't worry if there is crap buried.

As for the drainage If your planning to pave the rest of the area beside the house the decide now where you want the water to go.

Are you going to slope it towards a lawn and let it soak away or will you install linear drains and fall to that.

Your shed area can simply fall towards the main body of paving.

As for the temporary measure I wouldn't worry about the drainage, unless its really bad a bit of sub base and a couple of flags will not make it any worse. Just dig out to the depth you need and fire it down.

If there is existing paving that falls extra towards this corner it may not deal with that so well.

 

[Smileysmile]

The garden is elevated. Steps to lawn so it's a wall opposite my patio doors. So maybe a slim linear system along the base of the wall and tunnel from the there to the guttering pipe which is along side of patio door. I guess I have to do this regardless if I have flag stones with pea gravel or properly layed patio. I'm still researching the 'slope' the slabs have to be. If the slabs need to be level using a spirit level then that's going to effect the position of the bubble on the level if there's going to be a slight slope? I can't believe how thick I'm sounding reading this back

 

[r896neo]

Its one of those things that sounds super easy once you have done it once, but sometimes is hard to get your head around from scratch.

Forget a short level, you lay out falls over a distance. Ypu want about a 1:50 fall, you can go up to about 1:80 but less that than you need a high degree of skill to get it right and not have ponding.

So if your patio is 3m wide you simply divide 3000mm by 50 which gives you 60mm so one side should be 50mm higher than the other.