Cold roof insulation venting for garage

[nickfox]

Hi all

I've bought some celotex insulation to put up on the ceiling in my garage but I'm not quite sure on the ventilation. I want to place the whole sheets underneath the joists to seal the roof structure from the garage room. This is a cold roof configuration I understand. I'm not living in the garage so this level of insulation is fine but I don't want to risk any moisture damage to the roof structure.

Anyway, a video of the whole situation is here

Any advice is most welcome, thanks

 

[chappers]

Great thorough video, explains the situation perfectly.
My immediate thoughts are that you probably already have sufficient ventilation already, particularly if the garage isn't going to be heated or only heated periodically.
Your idea with the vents would certainly improve the situation, provided you are happy that they would be suitably protected from the weather. Alternatively how about fitting a row of trickle vents immediately below the guttering, running a bead of silicone over the top to ensure they are definitely weathered.

 

[nickfox]

trickle vents sound perfect, I had not thought of that. https://www.handlesandhinges.co.uk/what-are-trickle-vents/ I will look into this.
Thanks for the advice