I'd like to throw this out to the great 'brain-trust' here on the forum!
I have an old house that has a new 2-story foundation. I have a set of stairs (non-compliant-too steep and narrow) that goes up to the rather funky attic. Right now I'm analyzing whether it would be worthwhile to put a large bedroom with bath up there. I have a good design solution to make the stairs legal. The next main issue I'm grappling with is the 'floor joists' which also are the ceiling joists for the plaster ceilings below.
The joists are 2x6 and according to the basic span table I looked at are undersized for the span. I could run 2x8s but in order to keep the floor at the same level I'd rather not. I've been thinking of perhaps 'sistering' 2x6s with the existing joists....doing a nail pattern with 16d nails to essentially create 4x6s. I realize that they might not calc out as strongly as a 4x6 but certainly would be beefier than a single 2x6. Does anyone have any ideas of taking this approach rather than putting in 2x8s? (Obviously I need to know what my floor height will be in order to lay out the stairs correctly.)
(Btw, the work in this area will not be a full 2nd story addition but will be built within the envelope of the existing roof for the most part with the exception that there will be two sizeable gable shed dormers, one on each side of the ridge.)
Thanks guys for any feedback!