Warm flat roof. A couple of questions!

[theflyingpig]

Any warm flat roof experts on here??

Building is approx 6,m x 6m garden shed/workshop

My roof from the top will be:

EPDM
18mm OSB
Insulation
Vapour control
18mm OSB
Furring
Joist

Questions!

Can I get away with / should I use plastic sheeting as a vapour control layer? I've got a roll and budget says I should use it!

What timber would you usually fix around edge of lower deck to contain insulation and provide fixing for fascia? For example, If I use 100mm celotex? Do I need to rip down a 6*2?

When fixing to deck down, clearly I need some long screws that go through osb, insulation, osb... What length screws should I use?

Thanks for any input!

 

[Wayners]

Skillbuilder on YouTube may help as covered warm roof Vs cold roof.
Maybe watch that for information

 

[clayton]

 

[theflyingpig]

Interesting video. Thanks.

 

[nickjb]

Ideally you want to be hitting the joists with the screws. Easier said than done. Mark the joists then keep the screw perfectly square. Most of mine hit, when they miss you can see from the underside and give another go. Obviously you don't want too many extra holes in your vapour layer. I think I used 180mm or 200mm screws.

Plastic sheet is fine for the vapour layer.

I didn't put anything around the edge of the insulation. I just extended the cladding over the edge.