OSB Base for Shed

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Jupiter01

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I have a concrete base and want to build my shed on this. I plan to use 18mm OSB as the floor. I was advised to build a timber frame under the OSB board to give it strength and rigidity. Additionally, it was invested that this frame is raised from the concrete base so that it isn’t sat in water puddles. I was wondering if I could purchase some cheap
Paving slabs and the. Cut this in a few pieces (using my grinder) and then spread across the base of my floor frame?

Also, if any levelling is required, can I use some plastic spacers under the slabs or should I be using something else?

Thanks in advance.
 
Normally wood battens under the osb on slabs.
If slabs are near enough level all will be good as wood has a little give
 
Wayners said:
Normally wood battens under the osb on slabs.
If slabs are near enough level all will be good as wood has a little give
Click to expand...
Someone else suggested that I use concrete lintels as that will allow water to drain away from the gaps between the lintels. I was wondering if I can achieve the same effect with slabs that are cut into strips or do they not have the same strength?
 
My shed is still good and was here when I bought house in 1992. It's wooden floor on concrete.
 
Wayners said:
My shed is still good and was here when I bought house in 1992. It's wooden floor on concrete.
Click to expand...
I could place my wooden frame on the concrete floor but just thought that it would last longer if it weren’t sat in the rain puddles?
 
Shed should overlap base so that a) water doesn't get on to the base under the shed in order to form puddles b) reduces rainwater splashing up on to lower part of shed [look at the lower timbers of any shed/fence that sits next to hard ground and you will see why].
Failing that, if you're going to the effort of raising it off the concrete, then use something that isn't water-permeable.
 
Why Not Indeed said:
Shed should overlap base so that a) water doesn't get on to the base under the shed in order to form puddles b) reduces rainwater splashing up on to lower part of shed [look at the lower timbers of any shed/fence that sits next to hard ground and you will see why].
Failing that, if you're going to the effort of raising it off the concrete, then use something that isn't water-permeable.
Click to expand...
Since this is a lean to shed, the concrete base is the side passage of the house. It continues beyond this shed. That’s why I am wondering whether the base (osb board mounted on 2x2s) should be raised off the concrete in some manner?
 
I raised my shed on 2x3" tanalised timber set parallel, so air could circulate.
I closed the gaps with chicken wire to let air in but keep the frogs out.
Apply as much waterproofing solution as you can.
John :)
 
Burnerman said:
I raised my shed on 2x3" tanalised timber set parallel, so air could circulate.
I closed the gaps with chicken wire to let air in but keep the frogs out.
Apply as much waterproofing solution as you can.
John :)
Click to expand...
Wouldn’t it be preferable to use a non-water permeable material rather than the tantalised timber as this will sit in water? Especially, in my situation as the concrete base extends beyond the shed.
 
You can buy kerb edging or if you get slabs cut them to 3 or 4 inch wide strips to fit under the 2 X 2 timber supports and lay a strip of DPC on top of them so you won't get moisture soaking up into the timbers and you will be good for many years ahead.
 
DAZB said:
You can buy kerb edging or if you get slabs cut them to 3 or 4 inch wide strips to fit under the 2 X 2 timber supports and lay a strip of DPC on top of them so you won't get moisture soaking up into the timbers and you will be good for many years ahead.
Click to expand...
I can definitely cut slabs with my grinder and it will work out way cheaper than buying concrete lintels. Thanks for this. I will be buying some breathable membrane to wrap the shed. Can I use this between the timber and slabs?

One more, I need to level the slabs as the current concrete path falls away from the house. What can I use to bring this level and hence ensure that the base and everything above this is level and secure?
 
If my slabs are around 3inch wide when cut down, can I lay sand and cement underneath it for levelling or will this crumble over time?

Also, does it matter if my osb frame timbers don’t directly sit on one of these slab sections?
 
Jupiter01 said:
Wouldn’t it be preferable to use a non-water permeable material rather than the tantalised timber as this will sit in water? Especially, in my situation as the concrete base extends beyond the shed.
Click to expand...

The basic idea, is to make sure any timber is raised away from the concrete, via something impermeable to water, and high enough to allow air flow underneath. Bricks, slabs, even plastic blocks will work for that purpose. Bricks are usually easier, if you have access to some.
 
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Can I use sand and cement to level out some 3 inch wide slabs or will that crumble over time?
Thanks for your help.
 
Sorry to bother you again, but can I use sand and cement to lay and level these cut slabs or will this crumble over time? If yes, do I use building or sharp sand with my cement please?
 
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