On 8/22/2011 8:46 PM, Ken wrote:
I'm talking about the typical situation where a wood door starting to
stick in humid weather. I plane the door so that it no longer sticks
in the jamb, and then everything is fine until a year later when it
gets humid again and the door has expanded yet again and sticks.

I'm a woodworker, and fully aware of the effects of humidity
expansion and contraction. I have an end-grain stick cut from the
end of a tabletop I built that I measure it's length and use as a
gauge to know where in the expansion and contraction cycle the
environment is currently in. I always seal all 6 sides of the door
in question to limit the magnitude of the expansion and contraction
due to humidity.

The thing that I can't figure out is why do wood doors always only
grow larger over time? I have numerous doors that I plane to fit
very nicely, and then several years later I need to plane again
because they have expanded larger. Never in my life have I ever seen
a door that shrinks due to low humidity and causes an excessively
large gap. I see this on both interior and exterior wood doors.

So what is it about the expansion/contraction cycle that appears to
be biased toward expansion?

Ken

What kind of door (construction, material (solid/veneer/mdf), etc., etc., )?

In solid doors I see the shrink/swell cycle regularly; I'd suspect
something else going on other than just humidity changes...

--