Eaves ventilation

[junglejim]

I’m still trying to work out the insulation ventilation detail. We have a large overhanging roof along the side if the house but will need to enable ventilation above the insulation. The challenge is creating this ventilation gap and working out the best way to do it as the noggins are close to the external wall  (see photo). My thought is to over run the rigid insulation beyond the wall plate to butt up against the noggin. Then drill holes in the top of the noggin and vent from there. 
 

however I’m also thinking that this would prevent air from exiting top of the cladding So any thoughts or suggestion would be really appreciated.
 

Thanks for all the advice.

[Redbeard]

You may find you need a surprising no. of holes. Typical 'strip' eaves vent allows 25mm of clear vent path, so 25,000mm2 for each linear metre. If doing holes a typical 70mm round fascia or soffit vent gives 2000mm2, suggesting you'd need twelve-and-a-half per m. I don't usually use round vents but when I last checked them out we were amazed how many we'd need - many more than the contractor had proposed to fit.

[Dunc]

What are the noggins supporting? 

If it's not a joint in the OSB deck could you

a) remove them and placed further out - about 25mm outboard of the outer face of the cladding, providing an inverted L-shape type vent.

b) use a multitool or reciprocating saw to trim the top off all of them 25mm below the deck (providing your 25,000mm²/m vent). New noggins placed a little further out if required for deck support.

 

Or

c) trim 25mm off the bottom of the noggins to create a gap at the top of the cladding providing a Z-shape type vent.

[junglejim]

1 hour ago, Dunc said:

What are the noggins supporting? 

If it's not a joint in the OSB deck could you

a) remove them and placed further out - about 25mm outboard of the outer face of the cladding, providing an inverted L-shape type vent.

b) use a multitool or reciprocating saw to trim the top off all of them 25mm below the deck (providing your 25,000mm²/m vent). New noggins placed a little further out if required for deck support.

 

Or

c) trim 25mm off the bottom of the noggins to create a gap at the top of the cladding providing a Z-shape type vent.

Thanks for the suggestions. I’m wondering about taking out the bottom 2” of noggin and then adding a soffit vent underneath. Do you think that would work?

[ProDave]

The fact the gable end is insulated suggests this is a room in roof, so why has the roof not been designed and built as a warm roof not requiring ventilation?  SO much easier to detail properly.

 

Is it too late to change to warm roof?