"badgolferman" wrote:
My deck needs to be restained, but before I do that there are some
rotten boards that have to be replaced. These boards are rotted in a
corner at the end where they meet a step up. That corner is shielded
from sunlight and wind so leaves gather there and stay wet, hence the
rotting.

My deck floor is made out of 2x4s rather than deck boards. I'd prefer
to just cut back the rotten boards to the nearest joist(?) and put in a
new piece. If I go that route how far back should I go to ensure
stability? The nearest joist seems to be a foot away. Would it be
better to go back two full joists?

I assume treated lumber is necessary so the question arises whether
this will accept stain. How do I prepare it for stain and hopefully
make it match the rest of floor?

If I am picturing the deck correctly, it sounds like the 2x4's butt up to
step-up with the end grain near the step up. The end grain has absorbed
moisture and the boards are rotting.

If that's correct, would it be possible for you to cut _all_ of the 2x4s
back to the next joist, add some blocking in the open space and run boards
perpendicular to the 2x4's/parallel to the step up. This would eliminate
the exposed end grain in the area that collects leaves and moisture. Should
the new wood begin to rot, it would just be a matter of replacing one or
two long boards instead of having to weave in a bunch of 2x4's to make it
look right.

You would be incorporating a design element into the repair.