We recently decided to remodel our upstairs bathroom (5 x 11 ft) and I have a lot of concerns about the amount of weight that will be added. I have had a contractor check it out and he says it should be fine, but I am still a little worried. I realize it is hard to give a definite answer based on the information I can provide, but I am more curious if I need to seek a second opinion.

Basically we will be adding around 1,100 lbs of stone tile to the back, sides, and top of the area around the bathtub. My rough estimates of the total weight when the tub is full of water and an adult is in it comes to around 900 lbs. Combined, that is approximately 2,000 lbs in the small area around the bathtub. Based on some research, the typical home is constructed (US) to support 40 lbs/ft. Using this value brings the total weight limit of the entire bathroom to around 2,200 lbs. So unless I am missing something, I feel as though this too close for comfort.

The bathtub is against an outside wall, as shown in the photo below. Also attached is a photo of the joists directly below the tub - note the black pipe where the drain comes down.

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  • Any specs available for the floor trusses? If not, perhaps with some dimensions a load calculation can be reverse engineered...
    – peinal
    Commented Dec 10, 2019 at 12:43
  • @peinal Unfortunately I'm not sure. I would guess they are approximately 16 inches apart and made with Douglas fir wood. I had to take this photo through a hole in the ceiling so accessibility is very limited.
    – T James
    Commented Dec 10, 2019 at 15:31
  • 1
    The bulk of that weight is right near the end of the joist, over the foundation. To me it's not a concern, but some jokers on the internet aren't going to give you the reassurance you're after. Ask the truss manufacturer or hire a local engineer to take a look. There's no shortcut to surety.
    – isherwood
    Commented Dec 12, 2019 at 0:32

2 Answers 2


If there was a bathroom on the same location and layout I won't be really concern about the capacity of the trusses system to hold the weight that the support underneath needs

If you changing the layout (bathtub location) I will check with an engineer

It seems like the peak of the Truss is exactly below the tub area (two feet from the exterior wall) which is the strongest point but the system kept going supporting below

Hope this help

  • Thanks for the info! Due to the uncertainty of everything and based on a few comments I got here, I had a structural engineer take a look and learned that it should be more than enough to support the extra weight, especially since most of the tile weight will be supported by the exterior wall vertical 2x6s. I also learned that one of the side walls around the tub is supported by an even stronger truss system (which you can kind of see in the photo). So this eases my mind a bit. Thanks for your help with this!
    – T James
    Commented Dec 19, 2019 at 17:52

That looks to be an "engineered" truss system, not standard floor joist construction. If it were me and I did not know the original specs from the truss supplier, I would hire an engineer to determine the strength.

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