Best way to install shed on existing slab

11 Jul 2017
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United Kingdom
There's a 6ft square shed in my garden which was here when I moved in, and I'm looking for some advice on how to restore it to its former glory!

The shed is situated on a concrete slab which is far too big (probably 10ft x 8ft), and this means that surface water can run / pool under the shed. This has rotted the bearers, the floor, and started to rot the baseplates of the walls.

My aim is to replace the rotten timber and put a new floor in.

What is the best way to build this shed back up? If I just put new bearers in, they'll be sitting in water whenever it rains. A temporary fix, but not a job I want to re-do every 5 years.

I wondered if I could suspend a frame on some kind of metal supports which are screwed into the slab, and then fix the shed to the frame? Does anybody know of any suitable system?

Another option would be to attempt to dig out part of the slab so that it is the correct size for the shed.

A third option might be to put a course of bricks down, and put the bearers on those.

Opinions and expertise welcome!
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A bed of bricks, mortared in on a bed of mortar, sounds a good idea but keep it fractionally smaller than the shed base so the shed walls overhang the brick base.
This will keep the bearers out of the water and any water running down the outside walls will drip off past the base on to the original concrete base.
Thanks for the feedback.

My latest thought is to sack off the timber floor / bearers entirely, and instead lay 2 courses of bricks as a border, stick a DPM over the whole lot and fill the middle in with concrete. Probably cheaper overall and will last longer too. Sound alright?
How bad is the rot in the sole plates? If it is bad then rather than try replacing them it may be better to just buy a new shed,
I like your idea of a concrete floor but they can be very cold under foot, If the plates are pretty sound then removing the source of damp is often all that is needed to prevent further damage, Again, make the base fracrionally smaller so rain run off will drop past the bricks and away from the wood.
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They are pretty bad.

Pricing it up now, and I'm probably looking at around £180 to restore it, whereas a brand new shed is probably over £400. Neither option is looking particularly good for my bank balance!
tiles slate bricks part slabs topper with felt or dpm in a grid pattern perhaps 600mm-24" this will lift the timber off the concrete
as long as the bricks or whatever are greater than the pooling depth the wooden bearers will be safe
Lever up each side in turn and slide in A concrete post, cut to fit .
Thought i'd give an update - decided to get rid of the shed completely and will lay a new slab of the correct size in a different location next spring. Cheers for the help though!

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