Questions Re Shed Base

Furton

Furton

Furton

Soldato
Joined
9 Aug 2003
Posts
2,713
Location
Liverpool
After reading a few threads on here in regards to Sheds, I've ordered myself a 6x4 basic shed from Tiger Shed.

I now need to construct the concrete base before it arrives, but just want to check a few things here.

  1. I've excavated to 20cm with the intention of putting in 10cm of hardcode and 10cm of concrete, assume this is sufficient?
  2. What's the difference between Hardcore and Ballast, what would you recommend for the base and the concrete mix?
  3. Any issues with using sharp sand instead of builders sand? Reason being that I have some re-pointing to do which I need sharp sand for
  4. I'm intending to store my bike in the shed. In order to secure it I thought about putting an eye bolt in the concrete whilst it dries and cutting a hole in the shed base to tie the bike to. Any reasons why this may not work?
  5. I've I should make the shuttering circa 5cm longer and wider than it needs to be for the base, any reason why?
 
For a plastic shed I would say that is more than sufficient

hard core is used as a loose infill and is the compacted base layer to most paved or concreted groundworks.

ballast is the name given to sand and aggregate that has been mixed together and is the main ingredient in concrete.

sharp sand should be fine for a shed

I'd be tempted to get a metal pole designed/built taht I could run a chain through and around the bike, it would also act as a stand for it. Your option would work if it was big enough eye. I'd be worried about how easy it will be to rip up. You could just cement a chain straight in.

By shuttering I assume you're talking about the wooden frame use to hold the cement in while it dries? As long as the concrete base isn't sticking out further than the base of the shed I would think the only reason for it would be to reduce the risk of cement seeping out and making it easier to pull off afterwards. Not sure on this one myself. It's never a bad idea though to have the hardcore larger than the cement base going on top, purely to help with drainage.
 
Ballast; sand\small aggregate mix, as above.

Hardcore - probably sold as MOT type 1. Has various particle sizes ranging from ~20mm to tiny. Theory is, when you whacker plate it, they interlock, forming a solid base.
 
AHarvey said:
I'd be tempted to get a metal pole designed/built taht I could run a chain through and around the bike, it would also act as a stand for it. Your option would work if it was big enough eye. I'd be worried about how easy it will be to rip up. You could just cement a chain straight in.
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If you do go with a chain make sure it is incredibly thick. Most bike thieves I deal with down my neck of the woods carry bolt croppers as standard and I've seen them get through quite hefty chains.

We recommend D Locks rated by someone like 'Sold Secure'. Depends I guess how valuable your bike is.
 
8" is probably overkill but wont hurt and it will outlive the shed 10 times over.
The base should match the dimensions of the base of the shed. Ideally you want the panels to ever so slightly overhang so that any water that runs down the panels or from the roof doesn't accumulate at the base.
 
AHarvey said:
For a plastic shed I would say that is more than sufficient

hard core is used as a loose infill and is the compacted base layer to most paved or concreted groundworks.

ballast is the name given to sand and aggregate that has been mixed together and is the main ingredient in concrete.

sharp sand should be fine for a shed

I'd be tempted to get a metal pole designed/built taht I could run a chain through and around the bike, it would also act as a stand for it. Your option would work if it was big enough eye. I'd be worried about how easy it will be to rip up. You could just cement a chain straight in.

By shuttering I assume you're talking about the wooden frame use to hold the cement in while it dries? As long as the concrete base isn't sticking out further than the base of the shed I would think the only reason for it would be to reduce the risk of cement seeping out and making it easier to pull off afterwards. Not sure on this one myself. It's never a bad idea though to have the hardcore larger than the cement base going on top, purely to help with drainage.
Click to expand...

Thanks for your responses.

So just to confirm

100mm layer of hardcore
100mm of concrete (ballast, sand, cement)

Any benefit to fitting a DPM? I know you would do this internally, but is it required for an external structure?
 
Furton said:
Thanks for your responses.

So just to confirm

100mm layer of hardcore
100mm of concrete (ballast, sand, cement)

Any benefit to fitting a DPM? I know you would do this internally, but is it required for an external structure?
Click to expand...

I've always been told at least 6 inches deep for the base, that includes driveways etc so 200mm should be more than adequate.

You may be better off laying 80mm of hardcore and compacting, 20mm of sand then place the DPM on top of that then concrete on top of the membrane. This will stop damp coming up through the concrete.

Here's a good guide on creating a base http://www.shedbaron.co.uk/index.php/garden-sheds-base-preparation
 
Dig your hole, shutter it and order 1 - 2m cube of readymix. By the time you buy a bulk bag of crush and a bulk bag of ballast, cement and hired a mixer you are going to be approaching the cost of buying it ready mixed and will save you a load of mixing and barrowing! (I'm in the process of doing a patio and wall and have used about 10 tons of 'stuff' with a mixer and am a broken man! :D).
 
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