If anyone is interested, I have FINALLY finished milling the cedar that
I had stripped out of our old solarium and off the side of the house
for our remodel. I posted the titular question back in October of
last year - it is amazing how little you can get done between the
months of October and February.

Ended up having to mill it into lap rather than t&g because of the
final thickness - 5/8" - which didn't seem like enough to support a
t&g. In order to maximize my yield from the wood I didn't cut to match
my joist spacing but rather will biscuit the ends of the boards and let
the joints hang in space. I figure the 18 years that the boards hung
either in the solarium or on the side of the house induced any twisting
or cupping forces to express themselves and the planing took it out. I
hope.

It was about 30 hours of trimming, ripping, beveling and rabbeting. I
think it was worth it. We'll see in a coupla years. Oh, yeah, wish I
had gotten that dust collector - the trips upstairs with the shop-vac
every 45 minutes to dump the dust sucked.

App

wrote:

....
my joist spacing but rather will biscuit the ends of the boards and let
the joints hang in space. I figure the 18 years that the boards hung
either in the solarium or on the side of the house induced any twisting
or cupping forces to express themselves and the planing took it out. I
hope.
....

If it's open-cavity wall, I'd be concerned a little about the ends. If
it's over sheating, that would keep it from buckling. If it's 16" OC
and seems pretty stiff might be ok...

Just a concern w/ lap...I've done similar w/ tongue and groove, but
there's only the one side of the joing w/ lap.

Halfway done with the install of the paneling. Its going in nice,
luckily about two-thirds of the butt joints are falling on joists out
of pure good fortune.
The seven or eight that did not fall on a joist seem really solid.
Sealed both sides of the boards to help prevent any future cupping or
twisting due to moisture.

Even SWMBO is happy with the outcome, but schedule slippage has got her
undies in a bundle.

And I still gotta order and put down flooring (bamboo, vertical grain),
trim out the room, put up aromatic cedar in the closet and touch up all
my dings. Oh, yeah, by the end of March.

And work full time at my "real job", yada, yada, yada....

App

That which is never-ending never ends.