The bare minimum headroom required measuring from the 1st-floor plasterboard to the underside of your ridge needs to be at least 2.4 mtrs for a Velux conversion, and 2.3 mtrs for a Dormer, if you have less headroom and your property is detached you can have a roof lift. This option needs a planning application and as always, Building Regulations Approval.
The thought of a roof lift may even sound expensive and scary. The facts are, yes, this option is more different than the straightforward Velux or dormer, but only by 20%. Its more involved than any option we do, but you do not need to move out, the disturbance is no more than the Dormer option. It takes 2 weeks longer but weighs this against the benefits, a huge roof space is now available to be used as a Master bedroom, possibly en-suite and dressing room? or perhaps 2 bedrooms? or a home office? it’s only restricted by your imagination.