Flat roof where windows extend above joists

[cheradenine]

I am considering some options around remodelling the back of my property to knock down an existing flat-roofed construction and replace it with a marginally larger one with large glass doors (roof size of ~5m by 2m or thereabouts), with probably a zinc roof. I will require a structural engineer to design some beams, but I'm exploring ideas so I know what I want to ask him and not waste his time.

I have seen a number of pictures of designs that look quite appealing to me, in that what they appear to have done is to make the area above the window look - from the outside - much thinner by putting the window in front of the roof joists.

That might not make total sense. A picture is worth a thousand words so:

I'm looking for drawings that will help me understand how it has been constructed. I'm assuming that it's a warm-roof type construction, and that the doors transfer the majority of the weight to the bottom. What I'm not sure about is the detail around the overhang that presumably the top track attaches to, and how that's connected to the front beam so that it's all strong enough. I don't know if the structural deck (e.g 19mm plywood sheet) is simply left proud of the front supporting I-beam and that is sufficient (and thus the outside 'lip' is the height of the plywood + insulation) ?

Is there a name for this that would help me target google searches?

 

[^woody^]

Why do you need to know the construction detail? Are you doing the technical design work?

 

[cheradenine]

I haven't really decided yet. The last time I did an extension (previous house) a friend who does designs and technical drawings for buildings drew up the plans for submission to building control, but I did much of the back-and-forth, (e.g calculations for the compliance with part L1b).

This time around I want to do more myself (to be 'challenged and rewarded'). I could easily just do the same thing as last time (draw me up this and this) but that feels a bit like letting someone else do my entire jigsaw puzzle rather than fitting in the last few bits.

And - who knows - I might end up actually doing parts of the build (subject to spousal veto). In which case I'll need to know how to fit it all together.
.

 

[^woody^]

Well it seems to me that the roof could be a standard flat roof with the joists either extended over a beam to catch the door frame, or the frame just fixed to the face of the joists and the deck extended over the frame.

It should not be difficult to detail it.

 

[tony1851]

Either way there is some potential for cold-bridging if not detailed carefully.