Coroline condensation catastrophe

[HumphreyDroopingpurple]

Good day to you all.

I have a lean-to outbuilding, which was originally roofed with ply decking and torched on felt.

This summer I removed the rotten ply, replaced any rotten rafters and purlins, and laid the roof with Coroline sheets.

It is now soaking with condensation

Have I missed a trick here, as thinking aboot the 1/2" ply plus felt will have had significantly more insulating properties than the couple of mil of Coroline is going to have, thus condensation was always going to be a problem

So what can I do? More ventilation? It is currently open at the eaves but sealed to the breeze block wall (which is the high end), would adding vents at the top end help? Or should I go the other way and seal the eaves up in an effort to stop so much moisture getting in?
Should I build a ceiling underneath?

Ultimately, I'm not overly bothered about a bit of moisture dripping down inside, but will it cause my Coroline to rot? So if it's not going to ruin my roof, I'm might just live with it...[/i]

 

[HumphreyDroopingpurple]

Untitled

• HumphreyDroopingpurple
• 28 Nov 2014
• 1

My poor roof! Looks like it's going mouldy already!

 

[Burnerman]

Happily, the Coroline wont rot as its basically pressed bitumen, and if your roofing timbers are tanalised then they should have a good life too.
Just now, exterior humidity is as high as it can be, so keep the door closed to your lean to when you can.
A separate ceiling will make things warmer but of course that boxes things in so you cant see any nasties starting to happen.
Ventilation is really what you need!
John

 

[HumphreyDroopingpurple]

Cheers for the reply, Burnerman.

I think I'm going to try to increase the ventilation as much as possible - add vents at the top of the roof (near the wall) and down at the foot of the timber wall, and possibly seal the eaves...

Hopefully my timbers won't rot!