Standing Seam - Cold Roof Ventilation

[SelfBuildSmurf]

I am about to start building the subdeck for a standing seam room, I'm getting splinters while I still procrastinate zinc, steel etc. I have been discussing the supply of Standing Seam from Pagurek with Patrick who has been very helpful but I'm after some pictures or advice from those who have done similar before I climb up onto the trusses and have at it.

 

The roof concerned is a gable roof, it covers the porch (extension) and garage (existing) and is a move away from the flat roof which was on the garage before. Trusses are in, 600mm centres and an 11 degree pitch, the entire roof area is about 48m2. Regardless of the metal covering I opt for the deck construction appears to be very similar the only obvious difference I can see being zinc may require the last rip of the deck to be 5mm thinner than the rest of the deck.

 

Attached are some photos of the roof as it stands, how I want it to look and a cross section of the deck I am considering. I can't switch to a warm roof (not enough clearance below existing house window where the ridge is) so I know I will be tight for space above ceiling and the roof near the eaves and I need to allow for sufficient ventilation. I also want minimal, if not flush eaves, but this area of the roof is giving me cause for concern when it comes to the roof and the breather membrane (for any condensation) terminating in the gutter,

 

For those of you who have done similar before, have you any photos of your eaves detail which you would be happy to share?

 

My proposed build up is outside to in

1. Standing Seam
2. Powerlon Metalix Breathable Membrane
3. 18mm Plywood
4. 38mm batten (Does VMZinc really require 50mm?)
5. Breather membrane (Strotex)
6. 800mm Manthorpe Continuous Eaves (to maintain space between insulation and breather)
7. Truss

 

Questions I am mulling over are

• If opting for the above build up does the breather membrane (5) need to be able to run off out into the gutter?
• If the continuous eaves roll (6) is below the memberane (5) am I asking for issues if condensation occurs between the two? (i.e. it can't condense and run into the gutter)
• How, with a flush fascia do you permit ventilation? Do I need to use some batten to keep the plywood rip out slightly from the brickwork?

 

I may be totally over thinking this so would welcome your thoughts,

[Mr Punter]

1 hour ago, SelfBuildSmurf said:

• If opting for the above build up does the breather membrane (5) need to be able to run off out into the gutter?  This makes sense to get rid of any condensation and moisture
• If the continuous eaves roll (6) is below the memberane (5) am I asking for issues if condensation occurs between the two? (i.e. it can't condense and run into the gutter) You could use a felt support tray at the end as it may be less prone to perishing than the membrane
• How, with a flush fascia do you permit ventilation? Do I need to use some batten to keep the plywood rip out slightly from the brickwork? Yes