Plywood to replace bathroom subfloor

[chablis]

Well, my husband finally fixed the leaks in the tub plumbing, but we also noticed floor softening. Some investigation revealed that the leak is coming from the separate shower pan, and went from underneath the shower pan to underneath the sheet vinyl. Apparently, Fleetwood didn't run the sheet vinyl under the shower pan. There is no way we would have noticed it until damage actually occurred!

Fortunately, we have a second bathroom, so haven't used that shower in months, postponing repair until warmer and drier weather.

What thickness and type of plywood should we be using for the subfloor replacement? We are planning on installing sheet vinyl as the floor covering, if that makes any difference.

Thanks!

[joedirt63]

hello, i just finished a bath in my daughters 87 zimmer, same issue with the shower stall. i've found that most thicknesses are 3/4 or 5/8 should measure it, don't be fooled sometimes the partical board exspands with the wettness and you can't get accurate measurment . make sure you get all of the damaged stuff out. i used 3/4 plywood exterior grade. pressure treated would be better if you can find it but it's costly. back in the day it used to be called marine grade,also i would make sure there's enough support around the drain under the floor pan, to reduce any flexing of the floor or pan it's self. i tend to over build sometimes.but you need to have a nice solid base, or floor to start with, these m/h flex enough on there own. the vinyl would add to water proff ing as long as it doesn't get wet again.

[JD]

Almost all mobile home floors are 5/8" particle board. I find 5/8" plywood is too flexible for floor use. I use 3/4" (23/32" actually) Sturdi-Floor tongue and groove. It is available at most home stores and costs about $23 a panel. Works great! The tongue and groove is a life saver when replacing floors over hvac ducting in the floor joists, where you don't have enough room to block and frame properly. It will end up a touch thicker than the 5/8" particle board and will need to be floated out with thin set of some type. I like Ardex Feather finish.