Hoping someone can give me some clues on how to resolve a damp problem in my tool shed.
The shed itself is timber frame clad in thick waney edge, with a concrete base. It's pretty substantial for a shed and very old, certainly it's on the plans from long before the house was built (1970s). It has a roof made of timber boards which had been felted and then corrugated plastic at some point fitted on top of the felt.
Despite the considerable age of the building, the cracks in its concrete floor, and the terrible state of the plastic (bits of it literally falling off) and the roof felt, and that rain very occasionally made it through the plastic, felt and boards, it was dry inside and everything in it stayed in perfect condition.
Then I decided to do something about the state of the roof. I removed the remaining corrugated plastic and fitted a corrugated steel roof, fixed in exactly the same way, over the surviving felt and fixed using the correct fixings with weatherproof washers, flashings etc.
Unfortunately although it looks great, since the new roof went on I started to notice rust forming on some of my tools - a year or so later, the problem has got really bad with some tools now rusting badly, despite regular attention with wd40. Evidently, there is now a damp atmosphere in there.
What I can't work out is how to fix it. Is it that condensation is forming under the steel and dripping onto and soaking into/through the roof boards then discharging that moisture into the shed? Or is it that moisture coming up from the broken concrete floor used to escape through the somewhat permeable roof but it now trapped by the new weathertight roof??
Should I insulate (with I guess celotex boards) and/or board out the roof, to stop warm air from the shed condensing on the steel - or try and fit a raised insulated floor?
(BTW I've tried opening the window to various degrees to try and promote air circulation, but that hasn't made any difference)
Any pointers gratefully received.
The shed itself is timber frame clad in thick waney edge, with a concrete base. It's pretty substantial for a shed and very old, certainly it's on the plans from long before the house was built (1970s). It has a roof made of timber boards which had been felted and then corrugated plastic at some point fitted on top of the felt.
Despite the considerable age of the building, the cracks in its concrete floor, and the terrible state of the plastic (bits of it literally falling off) and the roof felt, and that rain very occasionally made it through the plastic, felt and boards, it was dry inside and everything in it stayed in perfect condition.
Then I decided to do something about the state of the roof. I removed the remaining corrugated plastic and fitted a corrugated steel roof, fixed in exactly the same way, over the surviving felt and fixed using the correct fixings with weatherproof washers, flashings etc.
Unfortunately although it looks great, since the new roof went on I started to notice rust forming on some of my tools - a year or so later, the problem has got really bad with some tools now rusting badly, despite regular attention with wd40. Evidently, there is now a damp atmosphere in there.
What I can't work out is how to fix it. Is it that condensation is forming under the steel and dripping onto and soaking into/through the roof boards then discharging that moisture into the shed? Or is it that moisture coming up from the broken concrete floor used to escape through the somewhat permeable roof but it now trapped by the new weathertight roof??
Should I insulate (with I guess celotex boards) and/or board out the roof, to stop warm air from the shed condensing on the steel - or try and fit a raised insulated floor?
(BTW I've tried opening the window to various degrees to try and promote air circulation, but that hasn't made any difference)
Any pointers gratefully received.