I am finally getting round to replacing my 20 year old allotment shed which is in a disgusting state. I'm looking at buying basic one online but many of them give options for shed bases. They either have no base, have a basic wooden base or a fancier tongue & groove one. My old shed had a wooden base but we also put in on slabs. Soil then got between the base and the slabs and rotted the base.
Has anyone any views/experiences on the matter?
Personal preference would be:
Concrete floor with polythene membrane below 30mm screed. Finished floor above surrounding land by , say 75mm. Brick course(s)to add headroom and discourage rodent entry. Build in rag-bolts or coach bolts to bolt down shed for security and hurricane resistance! Depending on how you wish to use the space, maybe racking or a bench within, to try to keep the floor clear.
Me PKL always leaves a good air gap under the base, and we keep leaves and soil from building up around the base.
I had a new one at home about 3 years ago. I laid a base of 2' x 2' council type slabs and then used edging slabs to raise the shed struts off the slab base. Increased my overall costs a bit but well worth it. Only 1" or so off the slabs so the cats cannot get under it but gives air flow to keep everything fresh.
If only the base has rotted why not replace the base and use the rest if the shed unless you are changing the size .
If using paving slabs again ass the base I would lift them and relay them on a GeoTextile /Terram fabric to stop soil creeping up between the joints.
Also any choice you decide on regarding floor or no floor I would look at protecting the timber from the slabs or soil by one of the means below to extend the life.
One method is to use flash band to cover the wood where it comes into contact with the ground.
Another method is to use a steel or aluminium strip painted and the screwed to the bottom of the shed or bearers of the floor.
Another method is to paint the bottom with bituminous paint.
It is important to note though that you do not seal the timber completely so it can dry out naturally if it gets wet. So if painting for example the bottom and an inch or two up the sides but leaving an inch or more of a bearer uncoated.
My personal preference assumes we are talking heavy damp soil like mine...
I always try to avoid any system that:
1) Rests wood on or in the soil and rots (bitter experience).
2) Has any hidden gap between the soil and the base where rodents can nest and scratch their way upwards (even bitterer).
For this reason I prefer to use 4 steel spike postholders (6 for a bigger shed) so the posts are above the soil with the decking floor attached to the post above the metal socket. This leaves a gap big enough to watch for nest-building and remove them as soon as they appear (never store anything under the shed - unless it's both ratproof and convenient enough to drag out once or twice a year).
It's worth building your own shed - shed prices are getting ridiculous. I'd also consider simply nailing a twinwall PC roof on - much easier to find stuff in a light shed (unless you want to store power tools - nobody steals iron hand tools these days).
Cheers.
I'll raise a shed above ground level if (or rather when) I put in a new one. Partly to get it above the periodic flooding, partly so rats can't nest underneath. An inch or so isn't much; I'll probably use breezeblocks with something solid - maybe railway sleepers - on that, and the shed fastened onto those. That way a cat can get underneath easily.