You could add 3/4" sheets of plywood/OSB to the subfloor if you wanted.
The code requires a 3/4" subfloor as a minimum, but there is no maximum until you exceed the physical limits of the structure. There are, of course, practical limits, as 12" of subflooring is ridiculous, but adding a 1/2" layer to an existing 1/2" layer to have a 1" thick subfloor will not give you any issues at inspection time. You won't be flagged for overbuilding the structure.
The extra 1/4" will come in handy should you (or a future owner) ever decide to go with a more picky flooring like tile or floating laminate flooring.
Answer from FreeMan on Stack ExchangeVideos
You could add 3/4" sheets of plywood/OSB to the subfloor if you wanted.
The code requires a 3/4" subfloor as a minimum, but there is no maximum until you exceed the physical limits of the structure. There are, of course, practical limits, as 12" of subflooring is ridiculous, but adding a 1/2" layer to an existing 1/2" layer to have a 1" thick subfloor will not give you any issues at inspection time. You won't be flagged for overbuilding the structure.
The extra 1/4" will come in handy should you (or a future owner) ever decide to go with a more picky flooring like tile or floating laminate flooring.
Yes, you can add another 1/2" layer. It was common in the US during the 70s and 80s to use one layer of 1/2" plywood and a layer of 5/8" particle board. Since particle board is crap, two layers of OSB is much better. In fact, I've replaced the particle board in such floors with OSB. The results were very nice.
Just be sure to fasten it down well to avoid noise, and stagger all joints. Consider a zigzag of construction adhesive between joists.
I'm starting on renvovation on a second floor bathroom. The entire second floor has always had a lot of flex and this is true for the bathroom as well. It turns out the entire second floor subfloor is only 1/2" plywood. There is some water damage around the toilet area that needs to be replaced and due to the damage of getting up the previous vinyl, I may end up replacing the entire subfloor. I am considering putting down 3/4" to allow me to tile the bathroom. Here are some photos of the current progress.
This presents a few problems. Along one length of the wall, the floor joist runs directly adjacent to the wall. There is approxately 1.5" of subfloor sitting on top of the floor joist that then runs under the wall. You can see that in this photo. My plan would be to use a flush cut saw to remove all the 1/2" plywood and cut a section in the adjoining room to frame in under the wall. This is not a huge deal as the adjoining room is already down to subfloor anyway.
A second option would be to replace the 1/2" plywood and then put something on top. The entire second floor of this house is a little strange in that it's more akin to an attic. The roof slopes down and the space above the toilet flange is currently only 5'8". Every 1/4" matters and I would like to avoid needlessly raising the floor height if I can help it.
Part of my plan in this renovation is to have a plumber evaluate if we can move the toilet flange parallel to the current wall but closer to the entrance to the bathroom. The toilet would remain 12" from the wall. But I would like to have a plan for the floor before I make more cuts and bring in the plumber.
Given the 1/2" subfloor, what would you do in this situation?