[wraiththe]

I am going to have to remove some floor and replace it. I am not sure this is a sound plan and am looking for some extra advice please.

I Have to get in to do a little pipe work (minor) and replace the floor and underlying gypsum board (I am guessing fire retardant.)

There are two web joists (one on each side of my cut.) Maybe @12" apart)

I could try to cut the floor to 1/2 of the width of the web joists on each side.... (@13" x 12"-16") and use it to support the patch which probably wont work to well.

Instead: I thought to screw two 2 - 2" x 8" boards on each side of the cut to the web joists and use that to support the patch. This would add much more support. I could take it one step further and add 2 2" x 4"s to the other sides for extra support. (maybe even use web joist hangars.)

When done, there will be a dreamline acrylic shower pan installed over it seated in mortar.

Does this sound like a good plan?

I have attached pictures.

 

[Nealtw]

Do why not set the depth of the saw and cut down close to the center of the joist.

2x8 on the side of them is fine if the top and bottom are 2x material, many are made like plywood and would split if you nail or screw to them .
When nailing to side the instruction show putting something on both sides of the web and nailing thru and that won't work for you.

 

[wraiththe]

Thanks Nealtw. I came back to post a similar repair done in our kitchen for a hole in the floor. The first patch did not work. this is how the second one was done. He did screw into that top rail... now I am going to be worried the floor will crack one day. Pics attached on how the last repair was done.
(Course this had a gypcrete pour over it. Which is difficult under a vinyl floor.) Is it also worth mentioning that the board used under the shower is not the same type as in the kitchen.

 

[Nealtw]

Those are 2x4 trusses, you first plan is fine.