Expert: Bruce E. Johnson - 1/12/2010

Question
I have recently taken on a bathroom project that now has me concerned with the dead load I have created by constructing my own shower floor pan out of concrete, the structure underneath has 2" x 10" floor joists (16" o/c) over a 10' span.  I have built a shower that measures 4 x 4.5'  I calculate the pan weighs approx. 650lbs and I have yet to install the tiles which will weigh another 650lbs.  Should I continue with my project or seek help with adding additional support underneath

Answer
Hi John, at this point you are only adding 36 pounds a square foot to the floor in this area..I don't see how tile is going to add 650 pounds to the floor load unless the room sits entirely on the midspan of the joists.  Normally when I do an elevated floor pan in a shower I put the shower pan vinyl directly on the floor plywood and then float two inches of concrete on top of that and then do the tile. I have done similar projects on joist systems such as yours without any problems.  If you are worried about the weight you can maybe add an additional joist underneath if you have access.. I hope this information helps, please feel free to write again regarding this or other matters, sincerely, bruce e johnson..bejohnsonconsulting.com