Wayne Whitney wrote:
Hello,

As I've mentioned in previous posts, I'm rebuilding my porch deck.
Most of the deck joists are in good condition, except they are pitched
slightly wrong. I'm wondering if it would be workable to simply
sister on a 2x4 to the side of the existing joists, which are rough
2x6s for the 6' span. I would set the top edge of the 2x4 to the
desired pitch, which be anywhere from 0" to 0.5" higher than the top
of the existing joists. So the 2x4s would basically just be nailers
to accept the porch deck and transfer the load to the existing joists.

Any problem with doing this?

Maybe.

People tend to forget that a load on a sistered joist is transmitted to
the mated joist mainly through the nails and only small load component
from friction. Therefore, top mounted shims are structurally more
sound.
If you have a table saw, buy a taper sawing jig ($15 or so) and slice
off the needed pieces. Use construction adhesive and tack them in place
and secure with new floor boards and ring shank nails or screws as
preferred. Doing a dozen joists this way shouldn't take an hour; less
if you have help, more if the help brought a six pack. HTH

Joe