TIL the hard way that moisture meters lie on treated lumber

Last month I ran a deck job outside Boise and trusted my pin meter on some fresh pressure treated 2x6s. It read 12%, so I started fastening, then by Tuesday the boards twisted so bad the homeowner asked why his railing looked like a roller coaster. Turns out the treating solution sits in the cells and messes with the reading, you need the hammer style or just wait two weeks. Know of any other tricks for checking wet PT lumber on site?

2 comments

2 Comments

the_eric19d ago

The copper azole they use now is way worse than the old CCA for throwing readings off. That stuff migrates in the wood cells when it is wet, so you can get 12% on the surface and 28% an inch deep. I started carrying a small pinch of the sawdust from my drill holes and squeezing it in my fingers. If it feels damp or clumps up at all, it is too wet, no meter needed. Also check the end grain, if you can see the treatment line looking dark and wet right at the cut, your fasteners are going to pull later.

the_robert18d ago

Yep, @the_eric nailed it. That sawdust trick saved me too many times to count.