Questions about replacing my deck floor

[jack]

I am just replacing the floor boards; what would the proper term be? Anyhow...

My joists are 16" on center. The old boards run diagonally. First guy says the new synthetic (undecided at the moment between composite or PVC) boards have to go perpendicular because they would have inadequate support otherwise. Second guy says diagonally is fine.

Second guy says once the nailed in old boards are pulled out the joists won't take new screws; he will attach 2x4s to the joints to take screws. First guy doesn't think that is necessary.

First guy or second guy right?

Third guy (well, actually the first chronologically) spent 2 hours measuring and showing me samples. Never heard from him again; won't answer my calls. Odd.

[Mikepier]

Since your boards run diagonally, your deck boards are spanning more than 16" depending on the angle of how your boards are layed down ( 30,45, or 60 degrees) You should check with the manufacturer of the boards to find out what is the maximum span the board can go and at what angle. You can probably find the specs online. Your joists can still take screws. Why the guy said that to you I don't know. When I did my deck I pulled out the old nailed-in boards and screwed in the new ones. No problems. Forget the first guy, does not sound like he's interested.

[Edwin Pawlowski]

Check the spec on the composite boards. Some require 12" center for proper support.

If the screw happened to go into the nail hole, it probably won't hold well at all. If it goes next to a hole, it will hold just fine.