Moisture meter accuracy in cold timbers – GreenBuildingAdvisor

Hi all, getting ready to install a post and beam style floor system using engineered inclined screw connections.  Per the manufacturer, the screws (galvanized) are intended for dry service conditions (moisture content <19%), otherwise I need to switch to stainless steel which has a lower strength, more expensive etc. 

The Doug Fir  timbers are 6”x12”, and have been seasoned with good air flow for 4 years (climate zone 4c marine). A cheap pin-type moisture meter is giving me readings of 22%, which is considered “wet service “. But many meters are calibrated for wood at -65 deg f. Do wood moisture readings change that much with temperature change, similar to RH of outside air vs interior air?

Also, my meter has only two settings, softwood which gives me the 22% reading, and hardwood which gives a 16% reading.  I’m guessing Doug fir, which has a specific gravity of .49, is somewhere in between. Do I need an expensive meter so I can program a specific gravity of wood species? 

Does anyone come across these issues? thanks!

adam