Of all the loft conversion structures this kind of dormer is probably the most difficult and complex to incorporate into a property when converting the attic.
It is obviously the rounded eye style that makes it so complex yet this is a traditional design in the UK.
The rub is that this type of dormer was used in rural England on cottages with thatched roofs.
Thatch can of course be manipulated and shaped rather more easily than the timber and tile used in modern construction so unless your property is an olde worlde thatched cottage atis kind of dormer will be difficult to include in your design.
Difficult but not impossible.
Its true that this kind of dormer is seldom seen but the quirky shape does have an appeal and it is possible to use it when converting the loft.
The problem for the builder is to firstly shape the timber structure and then to similarly shape the tiles to hang on the frame.
With the common box design the structure is constructed with vertical studs between a horizontal base plate and head beam. Everything is square and straight.
But, in an eyebrow dormer, the head beam and base plate are curved (concave and convex) which gives the builder a real headache. It can be done but once the framework is built comes the problem of cladding the new structure with tiles or other material.
Again, there are specialist builders and carpenters who can construct this type of dormer but of course the house holder will literally pay the cost of all the extra work involved.
While the extra expense involved is a drawback an even bigger negative is that this type of dormer will not add too much extra space to the roof and so is probably only worthwhile in an older property with a large existing loft area.
For more info see the related pages below
Ideas For Great Loft Conversions
Structural calculations for loft conversions are of course hugely important to ensure safety and that the proposed plans meet building regulations
What is the difference between planning permission and building regulations approval for loft conversions ?
Using And Fitting Loose Fill Insulation In Your Loft