In article , Tony Eva wrote:
So as far as I can tell, this floor movement can only be explained
by some of the joists actually shrinking by about 2-3% on their
vertical axis. What do others think? Is this normal, and if so,
how much shrinkage can I expect?

http://www.turningtools.co.uk/howdry/howdry.html suggests 1.5-2%
shrinkage across the grain for a 5% change in moisture content,
air-dried timber will have a MC of 18-20% and in a centrally heated
house this may drop to 10%, so what you're seeing is not unexpected.
Traditional joinery practice when making panelled doors or panelling
a room is to put the panels into grooves with no glue so that they
can move with the changing humidity.

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Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
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