Hello all-
I will soon be replacing a fiberglass jacuzzi with a Kohler cast-iron tub. The tub itself weighs 250 lbs, and 60 gallons of water weighs about 500 lbs, so the potential total weight of the unit when in use could be 750 lbs. (I figure an occupant of the tub would displace approximately his own weight in water)
The floor framing is 2×12, 16 in. O.C. The tub is 60 x 32, and the 60 inch dimension is parallel to the floor joists, right up against an outside wall so the weight is not out in the middle of the span. The subfloor is two layers of 5/8 plywood. The tub sits on four small feet each with about a 1-1/2 sq. inch footprint.
The floor already falls about 1/4 inch in 5 feet away from the outside wall. Should I be concerned about the dead load on the floor in general, or about deflection of the joists under live load?
-Doug
Replies
No. Probably not
This fixture and the water is actually called live load.
But for the immediate area it occupies, the load works out to 60#/sf
The design for your floor was probably worked out at 40# which is less than that, but the tub shares empty space also, bringing the average down, and there is a principle called load sharing, where if this was built right, the adjacent joists contribute to the load bearing.
The open question is what is the span ( length) of the 2x12 joists, and why are they sagging now?
It could be they were just not properly crowned when installed, or it could be there was improper engineering and somebody loaded the roof load onto the the center of that span so that they are already overloaded.
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also agreed, but you might want to put some extra blocking under the point loads, where the feet are, to distribute the weight even better ..
Good suggestion. If access permits, I'll add a little blocking.
The floor already falls about 1/4 inch in 5 feet away from the outside wall.
Paul and others....
sounds to me like it is just out of level.
Deflection and sagging were never in the OP's terminology.[email protected]
No, he didn't say it, but that is typically the case when it is lower to center away from outside wall. You could be right too, but odds are that it is sag.It now appears that this floor is over basement and there are lots of other obstructions.Who wants to bet against the chances that some plumber's helper or HVAC guy with a nice new sawzall had a sawdust party down there and these 2z12s are not effectively 2x12s anymore?To the OP, take a good look to see if these joists have been notched or overbored
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sawdust party, lol!
Good call based on his other posts.[email protected]
The span is about 14 feet, if I remember correctly. There are so many obstructions in the basement ceiling (ductwork, drywall, plumbing etc) that I can't really eyeball the joists to see if they sag. All I know is that the bathroom subfloor is 1/4 in. lower 5 feet away from the outside wall. Sounds like you think it's okay to carry that tub load. Thanks.
You're in better shape than most, but as Piffin said I'd be interested in why there's so much deflection in the floor joists.
Beer was created so carpenters wouldn't rule the world.
"I figure an occupant of the tub would displace approximately his own weight in water"
You'd better count the weight of the occupant too. Unless you plan on the water they displace overflowing and the person remaining fully submerged, the user's weight will be added to tub and water weight.
What I meant is that 60 gallons fills the tub to the rim. In order to get a person in the tub, the amount of water that has to be left out is probably equal to the weight of the person.Now if someone wants to fill the tub to the rim and then climb in... the water sloshing on the floor is their problem, not mine.