Sheds and Shed Bases

[Thorny19]

HI I’m new – I will be posting some DIY disasters this weekend .. I have had some beauties!


My latest idea is I have bought a nice new Metal Shed. I have bought this purley for security as the back of my property is open and an easy get away for would be thieves. The manufacturer state all over their website that the base has to be spot on level and firm.

Shed is on a 3 week lead time – now I need to build a flat, concrete base a couple of inches thick to put it on.

I was wondering if it’s quicker and cheaper to buy pre mixed concrete for this type of project (the stuff that comes on a truck and is poured in for me) and I’m not quite sure how to calculate how much material I will need. That also goes for if I mix the base myself, how to you work out how many bags of ballast and cement is required??

Thanks in advance for any help - may sound like easy questions to you guys .. to me a novice.. I don't know where to start!

 

[RedHerring2]

What size shed?
What type of ground is it going on?
What is the access like?
What use do you intend for the shed?

 

[studips]

where i am it would cost around £20 for half a tonne of ballast, say 5 or 6 bags of cement (£20) a bit of timber to shutter the concrete if not in a well defined hole below ground and a bit of effort to hand mix it.

that would do 2.4 x 1.2m to 75mm depth, the extra inch is worth it.

take the area (length x width in metres) * depth of concrete in m (3" = .075m) will give you metres cubed concrete required, * this by 1.5 gives you tonnes of ballast required. allow 12 bags of cement per metre of concrete.

a length of straight timber to tamp using the shutter as a guide (a piece of 4x2 timber) & if you would rather, borrow or hire a mixer for the morning.

 

[merlin50]

HI I’m new – I will be posting some DIY disasters this weekend .. I have had some beauties!


My latest idea is I have bought a nice new Metal Shed.

no you have just bought an outside shower, when its cold outside it will be raining on the inside

 

[Robert9999]

Why not use paving slabs? I have a shed on paving slabs laid on about half an inch of sand over bare earth which had beed pummled hard. There have been no problems for several years.

 

[studips]

i'm assuming he wants to bolt the shed down? pretty sure the metal sheds have no base of their own.

 

[Thorny19]

i'm assuming he wants to bolt the shed down? pretty sure the metal sheds have no base of their own.

Hi guys, The shed has an integral metal base and vents to stop condensation - this was a clain on their website.. I too was iffy on the moisture side of things.. but I have had a look around Dobbies (they sell them there as well) and these look pretty dam fine. Security is what I'm after.

The base size will be 1.8 x 3.3 ish, So pretty big. I have dug out down to 4 inchs (man that WAS tough) and ready to frame with some old pallete wood.. flippin raining now though. .. Shed details here. Will 4 " be enough??below. A mixer is pennies to hire for the weekend, but 3.3 x 2 x 4" down looks hard word to mix

http://www.asgardsss.co.uk/detail.php?pro_code=MB1&cat_level=0&cat_code=MG

 

[RedHerring2]

Concrete wise it's only just over ½ metre ³ (Great these Special Characters, aren't they?), so a couple of you will do that easily in a short day, with a mixer. (And you couldn't buy that in readymix)
Also use reinforcing mesh in there, something like A142. You should get a 3.8m X 2.0m quite easily.
Although, as Robert suggested you could get away with slabs (on a suitable subbase) and perhaps just a minimal strip footing, with a retaining block/brick surround.

However, you haven't mentioned what the access is like, although it's not much work to barrow a jumbo bag of ballast around.

You also haven't mentioned what the ground conditions are like.
I'm only a DIYer but I would have put down about 150mm hardcore under the concrete, whacked to refusal.

You could still do that by taking out another 50mm, then shuttering above ground for the concrete. Don't underestimate the pressure exerted by wet concrete.

I also would have used a 50mm sand blinding and a DPC. There's no point in using a dpc for a metal shed 'cos the condensation will be more than rising damp but you never know what the replacement structure will be when your metal shed has rusted away.

(I even put insulation under the slab for the workshop and garage, 'cos you don't get another opportunity.)