Newbie project - subfloor question

[Brian54]

Just a first time poster, but let me say what a tremendous resource this site has been for me already. You guys are so generous with your time and your knowledge! I'm sure I would have done this shower the conventional way if I hadn't found this site. Here's hoping I won't regret it!

I'm redoing a small bathroom - Kerdi shower, tiled floors and walls. Got "The Book", a roll of Kerdi and all the trimmings. Tearout is complete and I'm ready to get started. But as you can see in the photo, the plywood floor that was underneath the old shower has some minor water damage - staining and a few small cracks in the top ply. Otherwise, the plywood seems solid. To be on the safe side, I was planning to install another sheet of 5/8" plywood on top of the existing floor, but only inside the shower. Bad idea? Unless absolutely necessary, I don't want to replace this section, since having a continuous plywood sheet should add some strength (not to mention the fact that it would be a pain to cut out).

Brian

[Andrew21]

Brian,
Can you take a nail to it and push it through without too much force? Pick at it just a bit too see how deep the damage looks like. Can't see much from this distance, but it looks good to me. If you can afford another layer of ply, then go for it. Make sure you won't be too high for the drain.

[Brian54]

No problem with the nail test. I think I will go with the second layer of plywood. This would also solve the problem with the oversized opening.

The old drain is flush with the plywood; based on the Kerdi drain info, it appears that it would have to be cut down an inch or two to avoid an unusually thick mud pan. So another layer of plywood would simply reduce the length I need to cut off, right?

[Marge]

Brian, welcome to the forum.

Please keep us posted as to your progress...even if you don't need us.

[Brian54]

Thanks! I'll need all the help I can get!

Brian

[Andrew21]

I'm bumping this up because I don't know how to answer your question about your drain. Sorry.

[cx]

Welcome, Brian.

I'm not sure there is an outstanding question, Andrew. Last thing Brian said was correct.

There is a nice section inna whirl-famous Liberry showing alla dimensions of the Kerdi drain that should clear up any question about the necessary height of the drain riser.

My opinion; worth price charged.