Warm Roof ventilation

[thebadger7]

Hi all

We're having a warm roof installed, with woodfibre sarking boards above rafters and then ventilation above this using counter battens.

There will be a dry ridge system for ventilation at the ridge. What's the best way to ensure roof is ventilated from the eaves? Ventillated fascia?

Thanks

Luke

 

[a twig]

Just to ask the obvious and potentially granny egg sucking question first, I presume you’re using a wood fibre sarking board that is designed for the purpose (like STEICO Universal Wet)?

Otherwise you’d need a felt above it.

 

[a twig]

That aside, what are you using for your roof, tiles? Slates? Something else? As that might offer alternative ventilation options, but yes usually eaves vents.

Assuming you’re in Scotland I’m not entirely au fait with Scottish building codes so worth checking, but potentially a vented soffit could work provided the sarking doesn’t go all the way down to the end of the rafters and so allows airflow up behind the fascia

 

[Kearn]

Depends on the tiles. Old tiles will be rather draughty on their own to start with. Then at the eaves plate, don’t muck under the tile end, rest it on the plate and use bird combs to keep unwanted visitors out.

The whole ridge vent system is a bit of a new concept.

Our triple Roman roof has been on for at least 120 years, mucked in ridge and gable verges, largely mucked in tiles at eaves all pretty much with cement, then incorrectly insulated inside with no gaps and polystyrene and plasterboard… still no issues given how ventilates it was from the top surface.

I’ve mucked back in the ridge fully and also the gable verges in lime. But left the eaves open plus all the breeze that flows through ill fitting clay tiles…

 

[thebadger7]

It's steico sheathing board: https://www.ecomerchant.co.uk/steic...lyVacSBZmHorqBoYibVhafgzPuu49TQDedcbDKLMkj6F8

Build up is:
Underneath rafters = sheepswool
Woodfibre boards on rafters
Counter batten for ventillation
Breathable membrane
Tiling batten
Slates (real front, artificial rear)

I think the dry ridge is importnant in this system to get ventillation from eave to ridge, as the roof is only ventillated from above the rafters