I have a 240 gallon in my office on the second floor, and not against an outside wall of my house, I figured that the tank full with everything in it is about 4000lbs. Most houses built can handle the weight, because look at some of the bedroom furniture (long dressers and bed) and what they weigh, as long as your have a stand or cabinet that spreads the weight out you will be fine.
Deepblue