metal studs in commercial bath remodel

[Brian's Flooring]

Hi everyone,

I am new to this forum and am seeking advice. I am bidding on a commercial bath remodel where the client has selected a large format 12"x24" porcelain tile for both the walls and floor. During my initial jobsite investigation I have determined the steel studs underneath the current drywall are 20 gauge and 24 inches on center. The walls are 15' high, with a suspended ceiling capping the planned tile height at 9'. When I climbed up into the void space above the suspended ceiling I found a plywood decking has been installed above the bathrooms supporting the building's hvac systems...so with that much dead load above I am inclined to consider these to be load-bearing walls. The wall tile coverage will be approximately 1,200 sq ft with the longest walls being 22 foot in length

I am concerned with deflection on my tiled walls and load bearing capacity of these walls, so I began a little BASIC research about the spacing on the studs. TCNA and CTIOA references I have been able to find online indicate a metal stud spacing of 16" o.c. is recommended/preferred with a large format tile. I also found recommendations for medium bed mortar applications with LFT. I found two different recommendations to ensure the studs would not surpass the alowable "bow" within tolerances to meet deflection of L/360.

So, to wrap up this post... I am seeking advice on the following:

Assuming the studs will meet the tolerances for deflection, would I be safe in using 1/2" Denshield as a backer on the walls?

Any recommendations for thinsets on this application? I have to be honest, I haven't worked with medium bed mortars...having relied in the past on modified thinsets from various manufacturers.

I am tempted to pull in someone with more experience than I in these structural matters. I don't want my tile to come tumbling down in 6 months.

Thank you in advance for helping a guy out who seems to know just enough to be dangerous on a jobsite.

[Brad Denny]

Brian, Welcome.
Typically, there should be a line of communication in place for you to make a "Request For Information" (RFI) through your contact with the general contractor you are bidding with. Depending on the size of the project, be it an architect or designer, they should be the one to make the call on this issue. Bring it to their attention that you see a discrepancy between what is there and what is needed. If they are unwilling to take proper steps to rectify, remember that any design changes to the structure you make you are responsible for, so make sure you're right. I like for others to make those calls.