Just on – here’s how it happened.
The space for the Velux was made – to have roof windows or not was another one of those ridiculously drawn out and complicated decisions – for the following reasons:
I did a lot of research into sun tunnels / solatubes thinking they would overcome these three issues but after ringing the top three manufacturers to see what the minimum roof depth the sun tunnels could be set into (they are really designed for ceilings with a loft space above) and also asking about their U-Values, I gave up on the idea.