So much has changed since this video, and while in general I found it useful when I put up the Marley Universal Eaves Vents on my extension, I still had to research and make sure I was buying the right things, as some items/parts had been superseded/updated. It's worth getting some new videos from Marley highlighting these alterations to the product(s).

What a pony system. And that is absolutely shocking roofing. You need to be around 450-600 above the plate or the ceilings just to allow enough cover on the insulation. I would not recommend this.