Do *any* metal roofed sheds, NOT sweat?

[Harry Bloomfield]

Had the same in my dad's garage, a huge tin roof that used to helpfully drip all over the classic cars he kept, until the entire garage received an all-round insulation upgrade

I had a floor slab, that sometimes flooded, which added to the internal moisture. The slab had sunk slightly, so when it rained heavily, and the water couldn't get away fast enough, it would spill in, just wetting the floor. I installed a french drain, some while ago around the slab, which entirely fixed that.

 

[Safety First]

It's storage only.
Insulation in my 'design' serves only to reduce condensation on one surface - the roof, as this will drip.
If the steel walls are nice and cold, they can sweat out (and down) the water. So insulating them wont help.

The faster the whole space can react and equalise internal temp and humidity with outside, the better. So +++ air.

Option 1 - breather membrane was a bit of an oddity as I was thinking it could hold moist air off the steel roof until vented out front and back. What vapour goes through, if condensing, on above steel, could then drip and run out.

The membrane costs about as.much as the coverage of polystyrene sheets, whose job would be again to hold air away from the steel.

Polystyrene can be done as an afterthought if it turns out the roof does sweat off the bat.

I'd rather not board between the joists and make cold bridges of the joists themselves.. hence plan to overboard the lot.

I don't take the fire risk lightly.
If I planned any machine work, of any kind in there i'd not use ps

 

[Ivor Windybottom]

Get some vents! Just make sure they're mouse-proof.

 

[Safety First]

I had a floor slab, that sometimes flooded, which added to the internal moisture. The slab had sunk slightly, so when it rained heavily, and the water couldn't get away fast enough, it would spill in, just wetting the floor. I installed a french drain, some while ago around the slab, which entirely fixed that.

My slab has also tilted 50mm low on one corner. I set tiles/slabs etc as perimeter and intermediate points packed the same. This does make a small dyke at the low corner. I've cut a chase for draining.
At the high sides I have dpm throwing water back off the slab. Hopefully the planked floor will shrink up a bit and make gaps through which the slab can lose moisture.

 

[Safety First]

The answer is no.
The metal will send it's heat into the sky and achieve sub ambient temperatures at such speed, and for so much of the time be the coldest surface, that it will almost always have condensation on it.

And it has very little to do with the damp from within the shed.

 

[noseall]

Get some vents!

It won't make a blind bit of difference.

Insulate the sheets is the only way.

 

[robinbanks]

achieve sub ambient temperatures

Not unless it's been specifically coated to do so, which is highly unlikely in this application