Flush eaves / ventilation question

[JackOrion]

We are re-roofing an old out building. The building is 16m long, sloping downhill, and roughly 5m wide. So the roof is approx 2m from eaves to ridge both sides, with a fairly shallow pitch (16 degrees). We are re-using the old welsh slates and will be insulating between the rafters eventually.

 

We asked the roofer to counter batten in order to get continuous airflow and so insulation could fill up beneath the membrane, but now the bottom row of slates are in place, I can see that continuous airflow doesn't have an inlet at the eaves, where the fascia board is kicked up (and the batten the last slate rests on isn't countered, either)

 

Cross-section attached here – not 100% accurate but hopefully illustrates our situation.

 

Is a ventilation inlet at the eaves absolutely crucial here? (e.g. https://fascias.com/over-fascia-vent-ov10-1m-x-10mm)

 

Some searching online suggests not, since we're using permeable felt, and air will get in-between the slates enough to ventilate. (I will ask the roofer on Monday, he's very experienced and came recommended, and can only imagine he's of this school of thought too)

 

New to this, and slightly concerned it's too late to rectify this now much of the work's been done, so any suggestions / thoughts much appreciated.

 

Many thanks!

[nod]

37 minutes ago, JackOrion said:

We are re-roofing an old out building. The building is 16m long, sloping downhill, and roughly 5m wide. So the roof is approx 2m from eaves to ridge both sides, with a fairly shallow pitch (16 degrees). We are re-using the old welsh slates and will be insulating between the rafters eventually.

 

We asked the roofer to counter batten in order to get continuous airflow and so insulation could fill up beneath the membrane, but now the bottom row of slates are in place, I can see that continuous airflow doesn't have an inlet at the eaves, where the fascia board is kicked up (and the batten the last slate rests on isn't countered, either)

 

Cross-section attached here – not 100% accurate but hopefully illustrates our situation.

 

Is a ventilation inlet at the eaves absolutely crucial here? (e.g. https://fascias.com/over-fascia-vent-ov10-1m-x-10mm)

 

Some searching online suggests not, since we're using permeable felt, and air will get in-between the slates enough to ventilate. (I will ask the roofer on Monday, he's very experienced and came recommended, and can only imagine he's of this school of thought too)

 

New to this, and slightly concerned it's too late to rectify this now much of the work's been done, so any suggestions / thoughts much appreciated.

 

Many thanks!

You should have facia vent for the first slate to sit on To allow airflow 

[ProDave]

I found that standard fascia vent did not work, I used the OV10 vent instead https://www.centralpointbuildingsupplies.co.uk/ov10-1m-over-fascia-vent.html