It is a compliment, and it's not usually reserved for men. The Commodores song "Brick House" is referring to the same thing, they just couldn't put s**thouse in the lyrics and expect it to play in the top 40. It's a phrase that means someone is for better built than is reasonably necessary. An outhouse was usually a shoddily built structure, because all it basically had to do was keep the show and rain off of you while you did your business. If an outhouse was made of brick then it was FAR better built than normally expected. Hence, if a woman is build like a brick outhouse, then she is head and shoulders above the norm for a woman's build.