Plywood outbuilding on slab, starting to rot

[Perleman10]

I have a wooden outbuilding on a concrete slab base
The roof is pent and has quite a fall towards the back, with guttering

On this side, where the painted ply wall meets the ground, leaves accumulate and water splashes, resulting in the bottom of the ply (between 1-3 inches) getting wet and rotting

I was planning to address by using a wet rot hardener, expanding foam to seal the small gap along the bottom, and then bostick wide flashing tape to do a ‘L’ shape along the bottom of the ply wall and along the ground to stop further water penetration

Another idea was to lay a row of say 3-4 high bricks butted up against the ply wall as a more perminant solution, is that even feasible to do and have cement in contact with ply?

The issue is that the bottom of the joists will still be in contact with the slab but this edge seems to be the one with the issue as it’s beneith the guttering

Any thoughts on my ideas or suggestions how to tackle?

 

[oldbutnotdead]

Make sure the guttering isn't blocked and/or overflowing (if you've got leaves in the gap you'll have leaves in the gutter). Also make sure all the water from the roof is hitting the guttering- test with a hosepipe or watering can, see if water is over or under shooting. If it is overshooting then try building up the outer edge of the gutter (with cut down felt support trays or flashband or anything like that but check that you don't start getting splash into the eaves with that. If it is undershooting then you need to do similar to the inner edge of the gutter (or put felt support trays under the roof sheets to give the same effect.
Stop storing stuff up against the shed- you have to let the timber breathe.
Sweep the gap regularly so you don't get leaves building up.
Flashband on the bottom 6 inches of ply isn't a bad idea (it'll stop the wood getting wet from splash), don't make the L shape, you'll just end up trapping the moisture coming up through the slab and giving yourself an even bigger problem. Ditto the dwarf wall.

 

[Perleman10]

Thanks for this
The ladders are on the wall on hooks and well clear of the ground, is this still better avoided?

Prior to this the gutter had been blocked for a few years as I was new to having a house (lived in flats before) and wasn’t v. Practical. and leaves were accumulating on the ground, I am now clearing the gutter and sweeping weekly

Would you advise sealing the small gap at the bottom with foam? Or leaving it

I could trim off say the bottom foot of play and replace with marine (it’s currently wpb exterior grade).

I could also (more drastic) screw in day 4x very heavy duty coach screws at the bottom and use 4 bottle jacks to raise it a fraction and try to insert a strip of DPC. no idea if this would work or not. The building is full of gym equipment etc including a ton of weights (literally)

 

[oldbutnotdead]

Ladders should be fine, not much water hitting that face of the building (though you might want to lubricate the hinges & catches on the ladders every so often, they're steel so will corrode). And put a couple of bicycle chains on them- be really annoying if you got burgled & the burglars used your own ladders to do the job!
I'd leave the gap alone- presumably it is venting underneath where the joists are.
The ply that is rotting a bit- replace it if has got really weak, otherwise repaint it and leave it be.
Wouldn't bother trying to jack the thing up- if the shed is full all you'll do is rip the floor/side to bits at the jacking points. As long as there's airflow under the shed the joists bearing on the ground will last a good while (10 years minimum)- have a prod at an exposed end with a screwdriver and see how firm the timber is.