[jfguerrero1]

Hello Everyone. I am doing some remodeling in my daughter's house and she asked about remodeling the master bathroom. It is upstairs in a 2 story home.

The master bathroom is in the right side of the house (west side wall). There is a weight bearing beam that runs north to south under the outside wall, the living room below extends 8' further out in the 1st floor - the reason why the load bearing beam is in place (to hold the outer was of the bathroom upstairs).

The existing bathtub and shower run along this outer wall wall.

The current configuration of the bathroom has an acrylic garden tub (I am guessing it probably weighs about 250 - 300 lbs) - approximately 36" w x 60" h x 20" deep. There is a floor to ceiling wall that separates it from a (approx.) 36" x 36" shower. The shower pan is fiberglass. I have added a hand drawn image of what it looks like (not to scale - and also shows the living room downstairs).

The load bearing beam has a 2"x4" manufactured truss right next to it. Then there are trusses spaced 16" o.c. moving away from the load bearing wall.

What she would like to do is to remove both the bathtub and shower in the master bathroom and create one large shower in its place. The shower would be 42"x42" (in the main showering area) with an additional 36" x 58" shower walking/drying area where the existing tub is at. Again this would be just one large shower area. There would be a 40" knee wall to enclose the new shower area, with 52" tall glass on top of the knee wall. The walls and knee wall all tiled. Another hand drawn layout picture attached for this.

The new shower pan will be custom concrete. (As shown in the hand drawn image - the one that only shows the bathroom).

My question is, should there be concern with the additional weight of the custom concrete shower pan being added?

I am adding additional photos, but I didn't get any from under the shower. One picture, with the open window in it shows the load bearing beam (what the one under the upstairs bathroom also looks like). The second picture shows the trusses spacing and design.

Thank you in advance for your review and feedback.

 

[Boogityman]

I'll let smarter people than me answer to the weight but have you thought about using a Schluter base? We redid a bathroom last year and switched from an old mortar base to a Schuter...really easy to shape into custom (you just cut the foam)... Something to think about

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[HotRodx10]

Your remodel may not be adding as much as you think to the total load, if you consider the weight of the water that the tub would hold. 40 gallons of water weighs 330 lbs.

 

[jfguerrero1]

Thanks for your reply Boogityman. I did look into that. The decision to go with the concrete was based on custom size my daughter wanted and costs. But I'll give it a second look. If I can get a 42"x42" base for the main shower area I can then add the concrete to extend for the custom size. But cost will still be a consideration.

 

[jfguerrero1]

Excellent point HotRodx10. I had not considered that! Plus I am thinking of adding some cross braces from one truss to another with 2"x8" every 16" to give the concrete additional support - to avoid potential cracking if the house shifts.

 

[chandler48]

Your concrete base packing and liner won't add much weight considering what you are taking out. I would not worry about it since you are spreading the weight so wide. The concrete pack will only be at a max, 4" or so around the sides and less in the middle toward your drain. The trusses were probably specified at a lot more weight (say a refrigerator) on one spot measuring 9 square feet.

 

[rfehr613]

Thanks for your reply Boogityman. I did look into that. The decision to go with the concrete was based on custom size my daughter wanted and costs. But I'll give it a second look. If I can get a 42"x42" base for the main shower area I can then add the concrete to extend for the custom size. But cost will still be a consideration.

I don't know much about home construction and materials specifically, but i am a licensed structural engineer. In general, trusses tend to deflect more than equivalent-strength solid sections. So even if those trusses can support the load, I'd also be very careful to consider the deflection since this is a bathroom with tile. Even if you are able to mitigate differential deflection with cross bracing, global deflection of the entire floor system can still be problematic.

Honestly, your best bet if you have an issue or suspect you might have one is probably to just sister in a second joist to each one. Not sure how that's done with trusses, but i know it can be done since I've seen it before.

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[Nealtw]

If you are worried about deflection, sheet one side of the trusses with 1/2" plywood and then put block between the trusses at the bottom of the trusses and any movement will be the whole bathroom as one unit.