"AgaPSDIVER" wrote in message
...
I will be installing "beaded" plywood, 1/4 in., as a
ceiling for a
patio cover. I have 16 in. center rafters. I want to use
"deck wood screws" to install the ceiling so if I need to
get access
above again I can simply unscrew it. How close would the
screws
need to be along the rafters... every 6", 10", 12"
Thanks..

A literal reading . . .

.. . . indicates you intend to be able to remove and replace
the entire ceiling at will, rather than any given-size(s)
access-panel(s).

With 1/4" plywood, especially bead board, which is
directional, you should apply the board across
(perpendicular to) the joists with joints abutting at a
joist. Typically, for a neat, in-plane, smooth ceiling
surface, you should have solid blocking running parallel
with the board's long dimension along each edge. (Bead
board often comes with edges designed to abut and even to
interlock on thicker panels. You likely will not be able to
utilize this feature to easily remove any board alone, etc.)

Especially with 1/4" board, you should secure at no greater
than 8" oc along the perimeter of each board and no greater
than 12" within the field.

I would recommend a thicker board for the intent of removal
and replacement. 15/32" would be about the minimum. You
could then go with greater spacing, if you wanted to cut
down on labor. I would stick with the 8" and 12". 1/4"
board is not going to give you a very smooth, even ceiling
that takes full advantage of the beadboard appearance.
Certainly, with wider screw spacing, you are going to get
perceptible warping.

If just "staying put" is all you want, ignore my
recommendations. 12" spacing will hold the panels up on the
ceiling without falling. Just will not look very good this
time next year.

You might go with stainless steel screws with integral
grommets (same as used for installing trim in automobile
interiors) for the best, most uniform appearance and least
deformation of the beadboard. Layout your screw spacing
with chalk lines. That many screws (even at 12", which
won't look too good anyway) will really look crappy if
unevenly spaced and out-of-line. The grommeted screws will
also improve the appearance.

Jim