You could ask the owner of the building. The general rule is the smaller the room the less weight each plank of wood has to hold, the less weak spots the floor has, therefore the stronger the floor. The room my 125 gallon is in is I think 16x10 and the room my 110 will be going in is 12x9, in theory since the 12x9 has less space between the walls the floor should be stronger. Also, if you plan to setup a large tank on any floor that is not on the lowest floor, try to find your load bearing walls and place it directly on that wall. That is where the floor is the absolute strongest. Loadbearing walls are walls that support the frame of your apartment/house. They hold the roof and are built to keep your dwelling from collapsing or being blown over by the wind. The easiest ones to locate are the ones facing the outside of the building. Some places may have some in the interior of the place, but they may be harder to located. I have read that theoretically any tank 150g or smaller should not be an issue for almost any floor of any dwelling as long as it is on a load bearing wall. I still was very cautious when I set mine up. My apt building is very old so I didn't want to take any chances. I would think, and this is just my opinion, that if you are directly over a garage that your floors should be pretty solid. I wouldn't be surprised if they were either concrete or steel reinforced.