| 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?
You can just replace one section, provided that
there's enough joist under it for support, but it
won't look very good if you do several like that.
If there are a number of them next to each other
it'd be best to stagger the lengths of the
| 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?
You can also use fir. It won't resist water for as
long, but it has a nicer grain. PT 2x4 can be pretty
rough. Even the PT 4/4 x 6 doesn't make for a very
elegant look. 2x4 is not meant to be used for flooring,
so it's usually much rougher, often with big knots.
Fir can be stained immediately. PT should dry, at
least until summer. If you use a solid stain you don't
need any particular preparation other than maybe
washing with TSP solution. If you have a transparent
"wood color" stain you won't have much choice about
PT green showing through.
I guess you could might also use cedar, but 2x4
cedar is not available where I am.