Educate me - Construction loans for adding a camelback?

This is not something I have a ton of education on.

I have a 1,500 sqft shotgun uptown and am seriously considering putting a camelback (or maybe even a full 2nd story).

I owe 200K on it and it appraises around 5.

I hear that getting a construction loan has a lot of value vs. a home loan (lower rates, terms, etc...)

I could be wrong on that, but what can I expect to go after here? I don't need a homeloan, but know I could get a HELOC with so much equity.

I'm thinking of spending in the 200K area, roughly.

Is a construction loan the route here?

Any thoughts are appreciated!