Shed floor rotting, remedies?

[Alexnh]

My shed floor is rotting. The floor is built direct on the concrete slab. The roof doesn't project much beyond the walls or edge of the slab. It is below some trees and close to fences on two sides, so leaves build up against the side and are not easy to clear.

The shed ia built from wooden prefab panels. The floor is OSB on 2x2 joists. It's not great but I don't really want to rebuild the whole thing.

I want to raise the whole thing by jacking it up and place it on 100mm concrete blocks. Replace the floor joists with pressure treated wood and new boards.

Is that a good plan. How far apart can the blocks be? Should I place DPM between the blocks and the wood? Solid blocks or less dense ones? Any simple way to extend the roof

 

[scbk]

I assume the walls are sat on top of the floor? (like a standard shed?) Imo it's easier to take it apart , build a nice new strong floor, then put the walls back together ontop of this

 

[Alexnh]

Hmm. That might well be more sensible. I could also strip the roof and extend the overhang. I'm a bit worried that the panels are quite flimsy when taken out of the structure.

Probably a job for the spring.

 

[cwhaley]

When/if you build your new floor, make sure it doesn't just sit on a concrete slab -- best to put it onto something which raises it off the ground (sleepers, blocks, etc.).

 

[Alexnh]

Yes, thanks, that's part of my question: what to put between the slab and the shed joists. I was thinking of 100mm dense concrete blocks possibly topped with DPM. Also interested in plastic blocks)grids or legs, or concrete decking supports. How far apart should the blocks be?

 

[cwhaley]

Yes, thanks, that's part of my question: what to put between the slab and the shed joists. I was thinking of 100mm dense concrete blocks possibly topped with DPM. Also interested in plastic blocks)grids or legs, or concrete decking supports. How far apart should the blocks be?

I used railway sleepers but blocks and DPM fine -- don't need anything more complex than that.

As for the placement of blocks, it depends on your floor size. My shed is 10ft x 8ft, so I used 5 sleepers spaced every 2ft. Ultimately you want to make sure you're not leaving any long spans which are unsupported. I went quite high off the ground so I didn't get rodents making homes in the gaps under the shed.

 

[Alexnh]

Thank you.

Leaves gathering between the fences and the shed at the rear and on one side have increased the dampness. I wondered if I could extend the roof right out to the fence line to prevent this? No neighbour world be impacted, the pitch of the roof would take any water and leaves into a ditch on the far side of the rear fence.

 

[cwhaley]

Thank you.

Leaves gathering between the fences and the shed at the rear and on one side have increased the dampness. I wondered if I could extend the roof right out to the fence line to prevent this? No neighbour world be impacted, the pitch of the roof would take any water and leaves into a ditch on the far side of the rear fence.

An overhang is important to stop or reduce the impact rain, but not too large or it could be damaged in high winds. My overhang is 8" all around which stops most of the rain from hitting the shed. Not sure if would help with leaves though as they will be blown around in the wind.

I suppose you could extend it and then attach the roof extension to posts so nothing could fall down the gap (imagine a canopy roof). I have seen this done before.