A buddy of mine built a stand for a queen size waterbed to elevate it about 3 feet off the ground. We were on the second floor of a really really old beatdown fraternity house. That ***** held just fine....and we're no rocket scientists.
just wanted to update this. i did put the 240 on the second floor and everything has worked out. however i did put it against a load baring wall and the floor is concrete
4 story concrete building built in the 60's
military barracks so it had a common shower on each floor during my stay
the 4th floor shower floor just fell through the impact caused all the other floors to do the same. happened in the middle of the night so no one was in the showers
so concrete or wood or steel you never know so just dont sleep under it