Claw-foot, cast iron bathtub upstairs in "modern" house? 1

[racookpe1978]

Daughter-in-law wants to move a claw-foot, cast iron bathtub upstairs to their recently-purchased house. (Northwest GA, about a 7 year-old house, so it has the benefits of a new code compliance, little deterioration, but also the disadvantages of today's "more shoddy" slap-built untrained labor and imported material.)

The loading should be simple: But my instinct says to ask anyway.

Second floor. Tub will be on 4 feet of about 2x2 (maybe 2x3 inch) load-bearing surface. Feet can't be deliberately placed directly on the joists - or, if they do land on a joist, it's by happy accident.

Quoted tub weights vary from 375 to 500 lbs. Add water, two people (?), and live loads of stepping in, stepping out, etc and that gets you easily 1200 lbs divided into four point loads.

Anybody see problems?

(Other than the physical difficulty of moving it upstairs. (Been there, done that 30 years ago while moving my brother's cast iron tub upstairs. (But he had built his floors for the tub deliberately.) )

 

[Lion06]

I think 1200# is on the VERY heavy side. Is this a single person tub or a two person tub?

 

[racookpe1978]

I'm told two person, but can't confirm it. A one person tub would be 5 foot, probably only 400 - 450 pounds, with comparably lower body weight and less water weight.

 

[Lion06]

I think it's too heavy. You're taking an area that would normally see roughly 900 # (at most assuming the tub has a footprint of 6' x 3') over a uniform area as asking the joists to take 1200# + the flooring weight (if it's a tile floor 20psf is reasonable) of 360# = 1560#. It's close to double the design load on four discrete points. If the tub has a smaller footprint than 6'x3', the problem only gets worse.

 

[SlideRuleEra]

Anybody see problems?

Yes, but manageable.
If headroom and a step up are acceptable, one approach would be to convert the four point loads into a distributed load by building a structural platform to sit on the floor (perhaps out of 2x4's on edge with suitable finish flooring on it).

New cast iron tub specs appear to give the weight of the tube, filled with water. Here is one at 713 pounds:

http://www.vintagetub.com/asp/product_detail.asp?item_no=LG57RT7WRBW#FULLPRODUCT

other sizes are shown on the same website.

I agree that the heaviest load includes people plus a tub full of water... a person(s) could possibly step into a tub that was brim full of water. While standing, they would displace virtually no volume of water in the tub. When sitting, the load (for a brim full tub) would slow decrease as water displaced would flow out through an overflow (or over the side, if there is not an overflow).

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[plasgears]

The modern style of continuous support has more appeal. Try to talk her out of it.

 

[TXStructural]

I'd also look at the floor system. Flexure of the subfloor between joists could easily lead to cracking of tile, etc.
This can be managed by taking out the floor and or ceiling out below (which will be needed to plumb the tub anyway.)

Most likely, the house has a normal tub now, so when it comes out and before repairs to the floor are started, get in and beef up the structure and floor system.

Seems simple enough.

 

[msquared48]

Push comes to shove, you could always install the tub on a 6" raised platform using 2X6's to span across the existing joists and spread the load to more than one or two joists.

Might solve a plumbing problem or two while you were at it too.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[JedClampett]

I've got two of them next to each other in my backyard...

 

[msquared48]

So you and your wife are the ones we see in the TV ads?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[JedClampett]

Neither one of us are as good looking as those people.

 

[racookpe1978]

Raised floor using a braced and framed platform to span between the joists seems to be the best solution.

(Drat. Now I've got to get the thing all the way up the stairs, then lift it up seven more inches once I'm in the bathroom!)

 

[BAretired]

If you raise the tube 7", will it be too high to step over the edge?

BA