dpb wrote:
ls02 wrote:
On Oct 21, 10:08 pm, (Nails) wrote:
ls02 wrote:
What's the difference between RTD and CDX plywood for sheathing (walls
....
If it says "RTD SHTG", that means it's APA rated for use as sheathing,
and would thus be approptiate for your use on walls and roof.
....

One last note--whether the specific panel is appropriate depends on the
actual ratings for the panel and the application details --

Here's the definition of "Span Rating" for sheathing and how to
read/interpret the numbers (which is the actual rating, not the "RTD"
which is simply a conformance certification).

Then, there's what the local Code, if applicable, requires but this is
the basics of what the panel is designed/certified for in application.

Note that a panel can have the same Span Rating but be of varying
thickness owing to differences in material and/or construction.

Span Rating

The number that appears in the trademark on APA RATED
STURD-I-FLOOR, APA RATED SHEATHING and APA RATED SIDING panels. Two
numbers separated by a slash (e.g., 24/0, 32/16, 48/24) appear on APA
RATED SHEATHING. The left-hand number is the maximum recommended
center-to-center spacing of supports in inches when the panel is used
for roof sheathing with long dimension across supports (unless the
strength axis is otherwise identified). The right-hand number is the
maximum center-to-center spacing of supports in inches when the panel is
used for subflooring with long dimension across supports. When a panel
is applied as wall sheathing, the left-hand number applies to stud
spacing. A rating of 24 oc or more means the panel can be applied to
studs spaced 24 o.c. A rating less than 24 oc means the panel can be
applied to studs spaced 16 o.c. APA RATED SHEATHING panels may be
applied as wall sheathing either vertically or horizontally. In all
cases the panel should be applied continuous over three or more supports.

And, I suppose since we're at it, might as well put out the Bond
Classifications (glueline water resistance), too--

Bond Classification

Exposure ratings for APA structural wood panels designated in APA
trademarks as Exterior, Exposure 1, Exposure 2, or Interior.

* Exterior panels have a fully waterproof bond and are designed
for applications subject to permanent exposure to the weather or to
moisture.
* Exposure 1 panels have a fully waterproof bond and are
designed for applications where long construction delays may be expected
prior to providing protection, or where high moisture conditions may be
encountered in service. Exposure 1 panels are made with the same
exterior adhesives used in Exterior panels. However, because other
compositional factors may affect bond performance, only Exterior panels
should be used for permanent exposure to the weather.
* Exposure 2 panels (identified as Interior type with
intermediate glue under PS 1) are intended for protected construction
applications where only moderate delays in providing protection from
moisture may be expected.
* Interior panels or panels which lack further glueline information in
their trademarks are manufactured with interior glue and are intended
for interior applications only.

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