Garden Shed Base

RBZ5416

Distinguished Member
Another plea for help from the world's most incompetent DIY'er! :blush:

I have a 7 x 7 shed to put up & have looked at various options for the base. Easiest so far seems to be the idea of laying the shed floor on timber bearers, bedded on 2-3" of gravel. My worry is that the soil where the shed will go is extremely dry & almost turns to dust when dug. Method C here. So is the gravel likely to sink into the soil or even spread sideways causing the shed to list?

The other option is to sink concrete blocks on a dry sand/cement mix & lay the bearers on those, but the chances of me getting them all level are probably of the same order as a Lottery jackpot win... :rolleyes:
 
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Berties

Banned
Need a solid base for the flags first, don't want the underlying soil to move and settle about as the shed will start lean over. Sand/cement mix, then flagstones, then pressure treated timber posts, then the shed on top.
 

kav

Distinguished Member
If you dig down a few inches, then lay your gravel to bring it back up to ground level, and use a compacting plate to compress and level it, that's all you should need to do for a small shed like that. I would do what Berties said for a big shed, but it's a bit OTT for a 7 x 7 shed likely just to hold some garden stuff.

Some people would even think what I suggested is excessive - I know people who just throw down a few slabs and build their sheds on them. They usually end up a bit wobbly after a year or two though.
 

Berties

Banned
We're looking at a new shed too, the existing flags are all over the place, shed on top is pretty wobbily (old shed so don't care) couldn't put a shed on top. Huge job, new fance, remove flags, tree roots, go down x much for new hardcore. Need heavy machinery, diggers, compacters, hammers.
 

kav

Distinguished Member
If you're going the whole hog, here's what I did:

I have an 18 x 10 wooden garage, and for that I dug down 16", laid 10" of compacted gravel, and filled the sides with earth. Then used 6 x 2" boards for the frame into which the concrete was poured (3 cubic metres IIRC). I staked the frame into the ground roughly every two feet - concrete is heavy and will cause the boards to bow outward if you don't do this. The key thing is to get the frame dead level and perfectly square - if you can manage this, then it becomes straighforward to pour in your concrete. I also added in some steel into my concrete to reinforce it as there would be a car parked on it.

To get a nice smooth finish, get another length of heavy timber and lay it across your frame, and use it to level off your concrete - ideally two people are needed for this, but one can manage. As well as sluicing the board across, you can also slap the surface of the concrete with it - this causes the gravel in the concrete mix to drop slightly below surface level, ensuring you have a nice smooth surface when the concrete cures. Depending on how it turns out, you can also dampen the concrete and smooth it a little more, but sometimes too much faffing is counter-productive.

Also, a useful tip at this point is - if you plan on running electrics to your shed - to bury a length of conduit in your concrete, so that you can pass electrical cable up into your shed through the floor, if required. This helped me make a neat job when running power to my garage.

You can hire a small Bobcat for about £100 a day - it's phenomenal how quickly you can [-]wreck your garden[/-] work with one of those. I did everything I needed to do in about 4 hours. Compacting plate is pretty cheap, maybe £20-30. Concrete - far easier just to get it delivered and poured directly in, rather than trying to mess about with it yourself. I got 3 cubic metres which gave me a six inch base covering an 18 x 10' surface area. Can't remember exact cost but it was less than £200.
 
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Berties

Banned
yeah. Well going from the house to the shed, then you need isolator on the fuse box side, and RCD protected. Not an electrician myself by brother is.

oh outdoor circuit has to be seperate from mains circuit, it can't be just run off mains cable near the back door, own seperate run back to the fuse box (labelled outdoor)
 
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Flipper

Active Member
I did exactly what you are suggesting a few years ago, put a 7x7 shed on gravel and timber bearers. Sure enough, over time the shed has slowly sunk into ground, listing sideways and forwards :laugh:

When I get some spare time the whole thing is being ripped out so I can do it all over again, properly.
 

StevePSIV

Distinguished Member
I know people who just throw down a few slabs and build their sheds on them. They usually end up a bit wobbly after a year or two though.

Exactly what I am trying to rectify in my garden at the moment. Previous owners just had the 8x12 shed resting on some slabs and as a consequence it's ended up wobbly.

Just dug the earth up over the bank holiday weekend and will be pouring in the concrete this weekend hopefully!
 

IronGiant

Moderator
Another plea for help from the world's most incompetent DIY'er! :blush:

I have a 7 x 7 shed to put up & have looked at various options for the base. Easiest so far seems to be the idea of laying the shed floor on timber bearers, bedded on 2-3" of gravel. My worry is that the soil where the shed will go is extremely dry & almost turns to dust when dug. Method C here. So is the gravel likely to sink into the soil or even spread sideways causing the shed to list?

The other option is to sink concrete blocks on a dry sand/cement mix & lay the bearers on those, but the chances of me getting them all level are probably of the same order as a Lottery jackpot win... :rolleyes:

gravel will sink into the soil. But if you put down a heavy grade landscape fabric first you should be Ok.
 

dUnKle

Distinguished Member
Need a solid base for the flags first, don't want the underlying soil to move and settle about as the shed will start lean over. Sand/cement mix, then flagstones, then pressure treated timber posts, then the shed on top.

Exactly what we did

Dug down, flattened ground, sand cement mix followed by flagstones

Then shed (with wooden floor/base) was erected on that
Company we purchased from erected for free, but would only do so if the base was to their liking
 

RBZ5416

Distinguished Member
On the basis that I don't want to do the job twice, I've been out & bought some concrete blocks, sand & cement.

Thanks for the input guys. :smashin:
 

Berties

Banned
Well if you just use normal cable would be interesting what happens if you slice through the cable when you're digging your spuds.
 

IronGiant

Moderator
Same as would happen if I was drilling into a wall without checking if there was a cable there :)
 

Berties

Banned
Either way, any mains cable on the ground or underground has to be armoured type. Pyro isn't used anymore. You can't lay normal cable.

Brother used armoured cable along the ground, along the fence line so it's out of the way.
 

niceguy235uk

Well-known Member
Please stop giving incorrect information.:suicide:

SWA DOES NOT have to be used, if the conditions permit.

The shed supply DOES NOT have to have its own circuit.

I would suggest the OP contacts a local registered electrician to advise him accordingly.

Either way, any cable should be supported along its length, and not just thrown against a fence line.
 

Berties

Banned
Are you an electrican?

We've been informed can't just run off existing ring ie mains sockets on the back door. Any building that is not part of the main house has to have own circuit with isolator (by the back door) and seperate channel on the fuse box.
 

niceguy235uk

Well-known Member
Are you an electrican?

We've been informed can't just run off existing ring ie mains sockets on the back door. Any building that is not part of the main house has to have own circuit with isolator (by the back door) and seperate channel on the fuse box.

Yes i am, and what you have been told is not strictly correct.

I suggest you find another spark.;)
 

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