Patio rubber roof ventilation and cladding details

[GirlWithMission]

Hello everyone!

I’m building a house with external EPDM roofs to rear patio and entrance porch. We want to finish them with zinc facia and clad underneath joists with left over red wood cladding. 
Do we need to specify a Glidevale FV250 type vent at fascia and abutments? I assume that we don’t need insulation between rafters but how to manage condensation under the ply?

Our walls build up is 140mm SIP - 50mm cavity - 100 block with 15mm render. Roof joists are off the timber frame and block work should go through it. Do I need to have cavity tray above the joist and lead flashing? Building control said that they don’t care (?) much about it as it’s external to the house. But we are obviously want to have a quality roofs to last. 

Thank you very much!

 

[Dave Jones]

If the flat roofs are open to the elements underneath why bother with VCL and insulating ?

 

Wouldn't bother with vents either as wood breathes.

 

If on the other hand the space under them is going to be heated then you need to decide on a cold or warm roof design. Warm being far superior.

[GirlWithMission]

On 16/11/2021 at 07:19, Dave Jones said:

If the flat roofs are open to the elements underneath why bother with VCL and insulating ?

 

Wouldn't bother with vents either as wood breathes.

 

If on the other hand the space under them is going to be heated then you need to decide on a cold or warm roof design. Warm being far superior.

I see the point. We want to clad underneath hence I was wondering about the venting under EPDM as there should be some condensation in winter anyways. Thank you!