Standard post and beam construction uses 2 2x8's or 2 2x10's
for beams with posts every 8 feet with the beams on 4 foot
centers (there are probably other standards). That's what
my house uses along with T&G 2x6 across the beams. Also the
beams are composed of 2 pieces 16 feet long but the one
piece is offset one post so you get what appears to be a
continuous beam (nailed together) but no plates. Your
construction appears to be a simple variant and should not
be flimsy or need anything additional.

As for the squeaking, most of the squeaks probably result
from movement within the tongues and grooves. You need
somebody to walk around uptop to help you locate the exact
location of the squeak/groan while you are underneath. If
it is in the subfloor, your only course now is to screw up
from underneath. Use 1 inch material underneath to tie the
subfloor boards together and make sure it extends at least
two subfloor boards on each side of the squeak so that you
can put 2 screws through the 1 inch material near the squeak
and 2 screw in each of the adjacent subfloor boards.

On your one room, depending on your house layout, a change
in the direction of the beams in the middle of a room
doesn't seem right. And, you should get no deflection of
the floor unless you jump really hard and are heavy. Most
likely you have some pieces of bad/poor quality subflooring
(broken or partially rotten). If so, you can always add an
"I" of 2x6 or 2x8 material at any weak spots (use three 4
foot pieces to make the "I" and use metal hangers and
screws). If all of the 1/2 of the room is really unstable
you probably need to grit it out and add some more beams or
get a professional to advise you.

Andy Francke wrote:

"Jim Mc Namara" wrote in message
. com...
How far is the span of the existing joists, Andy? Not the o.c. dimensions
but rather how long are the joists? If all you do is add additional
joists, they will require the same support as the existing ones. If
they're
not supported over a long span (and keep in mind I'm not a structural
engineer) all you will do is weight down the areas between the existing
supporting ones when you screw down the floor to them.

Ok, here's the revised scoop. I hate going down in that crawlspace, but my
hazy memory clearly needed the boost. Maybe I have my terminology all wrong
and the "joists" I've been referring to are more properly "beams" (as in
pier and beam, which sounds like what I have in the crawlspace).

The joists are not sistered 2x boards as I stated earlier; they are solid
4x8s. They sit atop either 4x4 or 4x6 solid posts (it's a mystery why some
are 4x4 and some are 4x6 - there didn't seem to be an obvious pattern to
me). These posts are distributed 4 feet o.c. in one direction and 6 feet
o.c. in the other. The joists run on top of the posts in the "long" (6 foot
spacing) direction, and they are butted together on on top of the posts with
a 4 foot long 2x6 nailed to them to keep them together. I now realize after
coming back up that I forgot to measure how long the sections of joist were
between butts - but I would wager they span at least two of the posts (and
would hence be at least 6 feet.

Andy