How to best ventilate 18ft x 8ft wooden workshop

[JimDiGritz]

I've just had an 18 ft by 8 ft wooden workshop installed. It's got no windows since I wanted to make it secure (it will house all my tools, bikes etc) and I *may* convert it into a cinema room at a later date.

I've spent the last few days insulating it. After spending the past few months reading as much as as I could on the subject I opted to do the following:

Line the inside with a Breather membrane:

http://www.amazon.co.uk/gp/product/...&redirect=true&ref_=oh_aui_detailpage_o04_s00

I then installed some (cheap seconds) 25mm celotex/kingspan between all the studs and roof beams.

I finally sealed it all over with a reflective foil vapour barrier:

http://www.amazon.co.uk/gp/product/B00CP32H1K?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s02

I left two small gaps in two eave corners and used small 1" pipes to vent out under the eaves.

In retrospect there is nowhere near enough ventilation. Yesterday was a cool wet day and the humidity meter showed 79% inside the shed. In the morning I checked again and it was up to 90%.

I've got a bunch of 6mm plywood to line the interior but I need to sort out the humidity/ventilation before I start lining it.

Would a couple of plastic vents like these be enough?

http://www.wickes.co.uk/Wickes-White-Louvre-and-Flyscreen-225x75mm/p/713022

Any help appreciated.

 

[TheVictorian]

What was the humidity outside? You can ventillate all you want but if its 90% outside then it's going to be 90% inside!

Having said that, I'd still have one of these at each end probably: http://www.wickes.co.uk/Wickes-White-Gas-Vent-225x150mm/p/713018

 

[JimDiGritz]

Good point, I hadn't thought that through too well!!

I'll be installing the gas vents tomorrow!

Thanks