Adding a small cupola to the 1 1/2 story design thoughts?

[phalynx]

I would like to add a little cupola, maybe 6' x 6' on the top of our 1 1/2 story.  I was trying to think about how best to frame it.  I have 4' walls on the side of the top floor so I will have a ceiling joist running across each rafter.  I was thinking I could just build a double rafter and double ceiling joist (2x10) on each of the 6' walls and then cross a double ceiling joist (2x10) between the 2 ceiling joists that were doubled.  Then just build a 2x4 wall going up from there.  I was thinking about having a trap door so that I could just sit on the floor up top and use a built in ladder or even attic stairs to get to it.  Does anyone have any input on if this would be enough framing underneath to support this small addition.  It certainly won't have much weight up there which can be a lot right after Thanksgiving but that's about it.  Maybe a little chair.

I would like to build a square version of something like this.

[Redoverfarm]

Double rafters on the support walls I think would work and headers support for the front and end walls.  Plate on the sheeting to the rafters and header should be able enough support for the walls.  The floor will be the tricky part as not to loose structural intregity of your roof system if you are going to build the floor lower than the ridge.  A drop down stairs should work but will take away from your floor space (about 1/2 unless you can work it off to one side). They make a drop down ladder system instead of the folding stairs. Not quite sure where they are located not by a search on the WWW should get you somewhere. I 'm sure Peg can enlighten you.