I may have more
questions than answers on this one. I am not clear on the layout of this
addition and how it ties into the existing structure. Does the 16’ or 22’
dimension butt into the house? If the 16’ length is along the existing house,
then you will have a ridge that is perpendicular to the house with two hips
running down to the outside corners. If the 22’ length is against the existing
structure, then you will have hips at each end, but this will either be a shed
roof if the house has a second story or you will have to deal with the rain
runoff that will wind up between the new and existing roofs. Either way, I’m
having trouble visualizing how the interior would look with a partial cathedral
ceiling, and where the gable ends come from with a hip roof.
Here is a possible suggestion. Rather than trying to hide the access door on a
vertical surface in a space that is bumped up into a partial cathedral, see
what you think of this idea. On the end of the room where you are thinking of
having the access door, frame a recess in the ceiling that a standard pull-down
attic stair unit can fit in. You should be able to trim out the opening in a
manner that would give the impression that this was a skylight, unless you were
standing close to underneath it. You would want to modify the normal rope
handle that comes on these things with something more decorative. Installing
some built-in ceiling lighting would further reduce the visual impact.
You will need to look closely at the dimensions of what you are planning. The
slope of the roof will determine how much room you will have for storage. Don’t
forget that you will need to size the ceiling joists and rafters to support a
bit more load if you are going to be storing things in that space. You should
check your local building codes to see if they require finishing this storage
space off with plasterboard or making other arrangements for fire protection.
Plan on installing lighting in the attic so that you can find things without
having to carry a flashlight up with you.
If the existing house is two or more stories where the addition runs into it,
can you access the attic space from a room or closet on the second floor? If
the existing house is one level, can you enter the attic in another area and
create a path into the new space? Does the existing house have a hip roof? So
that the addition doesn’t stick out, you should always maintain the same style
when adding on.
If the roof slope is 4/12 (4” vertical gain for every 12” of horizontal
distance), and the ridge runs on the 22’ dimension, then the total distance
from the bottom of the ceiling joist to the top of the ridge is 2’ 8”. After
you allow for framing, that leaves maybe 1’ 6” at the highest point. I don’t
see getting a vertical access door in that space, nor is it much space for
storage.
You may want to consult with a structural engineer to make sure that you size
the framing adequately. If I totally missed the picture on what you are
planning, try me again with a bit more detail.