I agree that if it is not exposed to the weather (or touching the
ground since we don't know what you are spanning with this beam) I
wouldn't use pt lumber or plywood.
Real overkill would be to sandwich 1/4", 3/8" or even 1/2" steel
plate between the 2X's and bolt it all together. I only mention this
much overkill because the only time I can think of using bolts with
beams was in a past life as a framing carpenter. We framed out a grand
entry way that had curved oak staircases rising on both sides of the
entry and we built beams like this as the header(?) at the top of each
staircase tied into a manufactured exposed beam between stair headers.
Robert Smith
Jacksonville, Fl.




Mike Marlow wrote:
"Buell Boy" wrote in message
ups.com...
I've read a number of articles on this. One method said to use 1/2"
PT
plywood 10" wide triangular shims every 24 inches to prevent water
from
getting between the beams, and to let it dry out by the PT Plywood.

This seems odd to me since this would tend to weaken the beam? Does
anyone really do this? ALso I would thin kPT Plywood would be a lot
less durable than 2x10 PT? Is it really practical?

Also, let's say my header is 12' long. What carriage bolt spacing
should I use? I was thinking 24", staggered on-on-top,
one-on-bottom?


It would help to know what you're building a beam for. Unless this
beam is
exposed to the elements, I would not use PT at all. Also - where was
it
suggested to you to use carriage bolts on your beam? For normal
applications, simply nailing the beam up with 12's or 16's is more
than
sufficient. There's overkill, and then there's overkill...

--

-Mike-