Last month I watched a framer on a job in Tulsa shim a whole floor system using nothing but stacks of pennies and construction adhesive. I always carried plastic shims and would run back to the truck if I ran out. He said pennies never crush or slip, and after seeing him do a 30 foot span in about 20 minutes, I switched over. Has anyone else tried this trick or is it just a regional thing?
The part about pennies never crushing is the real kicker, but here's what nobody brings up. That copper is softer than the plate washers or steel shims most guys use, so it actually beds into the wood grain over time and stops any squeak before it starts. Plus pennies are uniform thickness, so you can do the math in your head for a slope way faster than digging through a bag of mixed plastic shims. Only catch is if the bank ever changes the penny composition, all your old stacks and new stacks won't match, so save a roll from the same year.