JAE...excellent questions.
I'm not sure I have good answers, only anecdotal experience.
I evolved into the building sciences practice. I started in structural design of tanks and other structures, then towers, then specialty stuff. After the tank design stint, I worked in a Geotechnical/Materials Engineering firm for 18 years, with such a broad clientele that we got involved in so many different things, usually testing construction materials, but also doing specialty testing, devising tests for special applications (once had to devise a testing frame for simultaneous orthogonal testing of the umbilical boom assembly for Atlas rockets, then run the tests).
I guess I've had about the luckiest career an engineer could imagine. I've never been "pidgeon-holed". My structural analysis background has allowed porting of that skill set to many different arenas (literally and figuratively on the "arena"!). As an example, while doing structural analysis and testing on a "major amusement ride" at a "major theme park" in Central Florida, we found that vibrations from running the cars that were made to replicate a famous, but short-lived stainless steel sports car, were imparting vibrations that the building structure would have trouble tolerating, since the building was designed as a static structure, not dynamic.
Could I do what I do now with only a Building Sciences background? Emphatically...NO!
Building Science doesn't necessarily rely on a single discipline of engineering and in some cases, no engineering at all. It is part science, part conjecture, part observational experience and part voodoo. It is also extremely broad and ill-defined.
Can building science be a career exclusive of structural engineering...Yes. It is mostly practiced that way. I just think it is better to have a broader background in engineering than a strictly building science practice would offer.
To my knowledge, there is no licensing for "Building Science". It is a specialty subset of either mechanical, structural or environmental engineering, when practiced by engineers. There are many out there who do pieces and parts of Building Science practice without engineering licensure. I don't like it, but it is fairly common. One example is in Roof Consulting. Many "roof consultants" are not engineers or architects. Many are former roofers (often from the "one year of experience, 20 times" variety). They are often allowed to practice in states that would otherwise require an architect or engineering license to do such things as design a re-cover roof system without appropriate structural considerations (I've investigated one where a contractor acted as a consultant, overloaded the roof during the initial construction and caused a collapse....one died).
Like many parts of our profession, we get those who think it's as easy as just picking things from a catalog and following a few cookbook procedures to achieve the desired result. Too bad we can't collectively put them out of business. I get on a high soapbox when we talk about unlicensed practice and usurping the term "Engineer" or "Engineering" by those who are not licensed.
Ok...I'll stop before I start ranting.
I'd be interested to get your perspective on this as well....
