What to do about shed rot?

[PeteWilliams]

I've been using a garden shed (built by the house's previous owners) as my workshop for a couple years and was about to insulate it. The walls were ply with a vapour barrier behind it, but just the studs and cladding behind that.

My plan was to stick a breathable membrane and kingspan between the cladding and the vapour barrier, but when removing the vapour barrier I can see the cladding is damp and starting to rot.

I've only recently painted the external walls of the shed and I don't think it's coming from there, I think it's coming from the ground up - the rot is worse at the bottom, especially on one side.
The shed is on a concrete slab and I think the wooden floor is just sat right on it.

You can see some photos here: https://photos.app.goo.gl/HDAsgjuD4KcKpLr98

I'm guessing the only way to fix this is to tear it down and start again, but it's a 20x15ft shed FULL of stuff I'd have nowhere to put while I rebuilt it…!

So, is there anything I can do? Even if just to slow things down?

All suggestions gratefully received!

Thanks

 

[scbk]

Is there ply (painted grey) over the cladding on the outside?


Ditch the plastic sheet, that is just holding the water in the timber cladding and causing the mould/rot.
Is there gutters? If not, fit some.

Wouldn't be a bad thing to jack up a corner at a time and slide some plastic dpc between the bearers and the concrete

 

[Wayners]

Primer preserver lash on in the dry weather will protect all the wood. Clear or coloured. Just empty what you can and use Archimedes lever to lift and slide some new timber posts under. Its amazing how much you can lift very easily. I moved a 12 foot shed with leavers...

 

[PeteWilliams]

Is there ply (painted grey) over the cladding on the outside?


Ditch the plastic sheet, that is just holding the water in the timber cladding and causing the mould/rot.
Is there gutters? If not, fit some.

Wouldn't be a bad thing to jack up a corner at a time and slide some plastic dpc between the bearers and the concrete

No, it's not ply. That's the painted side of the cladding on the outside.

Yes there are gutters, but due to poor drainage and it's location at the bottom of a slope, there's still quite a lot of standing water around the shed. I'm planning on putting in a set of french drains this year.

My concern about jacking it up is that the wood is too rotten and it would just break apart.

I've added some more photos so you can see a bit more: https://photos.app.goo.gl/HDAsgjuD4KcKpLr98

 

[PeteWilliams]

Primer preserver lash on in the dry weather will protect all the wood. Clear or coloured. Just empty what you can and use Archimedes lever to lift and slide some new timber posts under. Its amazing how much you can lift very easily. I moved a 12 foot shed with leavers...

I wondered about a preserver, but wouldn't that just seal the face of the wood, and mean the moisture that travels up the body of the boards has no way out?
I'm not sure it'd survive levering up, and there's only one side where there's enough room for long levers. What did you use for your levers? I'd have thought most things would bend/snap under the load?

 

[Wayners]

Primer preserver is a water barrier. Stops that bit rotting. Leaver I used 2x3 timber. Was the old boy next door idea. I thought it would never work but did easy.. If your have a leaver long enough you can lift the world he said. I lifted up and had 2 scaffold poles that acted as rollers. Just levered up 50mm. Levered to move too

 

[Malakym]

My concern about jacking it up is that the wood is too rotten and it would just break apart.

Air bags, will spread the load. Try not to do too much at once. You could get away with just one though ideally 3 to start (more the better of course).

The last ones I used were only a few mm thick so once I got the bearers off the ground a bit I could put the bags directly under them. I didn't even empty the shed (granted there wasn't any big things like lathes in there).

Leavers do work as Wayners mention, though can scar up the edge of the timber.