moisture meter

[sbhtennis]

I do have large humidity swings in the house... now 48% but in September it was 65% (when things swelled) . I have forced air electric..new furnace and heat pump, although did not use air conditioner much in summer (when it was the most humid).
If reinstalling bamboo how much would you allow for expansion at walls etc.
Would putting poly 6 mil plastic in addition to Aquabar set up a moist environment underneath??