I'm renovating a 4x5 ft. bathroom and I'm having problems leveling the sistered joists with the existing floor (the doorway). I've clamped the new sister joists to the old ones in order to see how it would fit. When I lay subflooring on the bathroom's joists, it is 1/4 in. higher than the existing subfloor in the doorway. How do I level it, so that it meets the existing plywood at the doorway? Is being a 1/4 in. out a lot?
Please see the pic below: I'm level east to west but not north to south. (And north to south is the critical direction as I need to tie into the existing flooring.) The joists are 2x4s on a slab. The house is 50 yrs old.