My inner sub floor is a inch and a half. Two 3/4 inch planks. My outside walls only sit on the bottom 3/4 inch plank.
The house was a bug hotel before I bought it. I have been repairing rot and bug eaten wood. I have to repair the floor under the outside wall. Where do I buy true 3/4 inch sub floor? I found some true 3/4 inch underlayment and used it on some patch jobs inside. Just added two on top of each other to get my 1 and a 1/2 inches. I was just reading on not using underlayment for structural flooring. Why? Seems pretty sturdy to me.
I also have tried adding all the various plywood measurements to add up to 1 and a 1/2 and it does not work. Always short an 1/8th or 1/16th. I am not too worried about using underlayment for minor repairs here and there on the inside.I will be adding another subfloor after all repairs are done. But I am weary on putting it solely under the outside wall if it is not meant for that. Also it would be nice to get away from underlayment. It is pretty spendy.
If I used the 23/32 plywood under my outside wall I would be off a 1/16 from my outside wall to my inside walls. All I want is some 3/4 inch plywood or some planks.
Damn metric system.
Thanks for all the people who post on here. I have gotten very good answers. Once I finish my house I will be able to post answers with experience besides just questions. Very good website!