Re: Second story addition on a 50's bungalow is it doable?? structure??
No one but a contractor from Boston is going to be able to tell you what is possible in your area. Having said that, I did a second story addition in San Jose California shortly after the big Loma Priata quake. We did nothing to the existing foundation, but did have to pour several large piers and foundation walls under the house to help support the upstairs. Other than that, everything else was retrofitting the structure for quake resistance.
2x4 framing has been acceptable for 2 story construction for decades, no reason you can't add onto what you've already got, the worst likely scenario is that you'll have to pour footings and foundation walls under the structure to support the additional weight like I did, depending on your floor plan and such.
Anything is possible, the question is generally, "what is it going to cost". You could start with the local building department, ask them what some of the requirements are for a second story addition to a 1950's structure. From there, contractors that specialize in such additions in your area would be able to answer a questions as well.
Before you start drawing bids (or pestering too many contractors ), you're going to have to work with an architect and/or engineer to design, do the load calculations, and draw the plans, then you can put the plans out to bid.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!