In a bathroom, due to rotten sub-floor and remodelling, I have to remove the sub-floor and put a new one (we're changing the location of the shower and the sink; the plumber's going to make Swiss cheese out of it).
The challenge is that most of the sides of the sub-floor go under the walls. Some of these walls are right over the I-joist, some are not.
Where it's possible, I'm thinking of doing something like suggested here:
- If the couple of inches of flooring you have not removed at the wall is solid, you can screw through it and into a piece of wood below it that the new floor can also be screwed to in order to make the edge supported, in a somewhat easier fashion. It's crudely equivalent to having a T&G joint in that the floor acts as a single piece.
But I'm less inspired about a proper way to fix it where the floor is completely rotten and unusable.
I've thought of doing something like this:
Since I have I-joists there, I thought about reinforcing the I-joists by putting in there 1" x 8", held by construction adhesive and 1 1/2" screws (those pieces are in green in my graphic). The plan is to make it fit snugly in there.
Then, with joist hangers, adding in 2" x 6" in-between the reinforced joists and use them as a kind of bridge (displayed in blue in the graphic; the joist hangers are not shown). The top of these bridges would arrive at the same height than the I-joists.
Finally, still using joist hangers, adding a 2" x 4" in-between the two bridges, right under where the end of the new sub-floor would arrive. (This part is the yellow one in the graphic.)
A couple of things to keep in mind:
- I will not have access to the sides of the I-joists that are not under the bathroom sub-floors, so I can't reinforce the I-joists on both sides.
- If that matters, I'll be installing ceramic tiles over the new sub-floor (after putting on there 1/4" cement boards).
- Is the idea suggested by the other post is the most appropriate?
- Is the plan suggested here makes any sense? And if it does are the planks sizes appropriate and should I use screws or nails to attach joist hangers (and what size)?
- And if it does not, what should I do instead?