PT Joists vs. non PT

[pioneergal]

Is it necessary to use PT 2x10' s for my floor joists  that will have a minimum of 24'' space between the ground and the joists?

I've been told by some that its necessary and that it's not by others.

Thanks,

Pioneergal in North Central Texas

.......where it's always hot and dry !

[John Raabe]

The general rule of thumb is that wood that is closer than 6" to 8" of the soil should be PT.

In well ventilated spaces such as a crawlspace or joists on a post and pier foundation would not normally need to be pressure treated.

[PEG688]

  Here in Wa. state the general rule is , #1 Exterior framing lumber must be PT .  #2 Any wood that touch/ sits on concrete, (ie Sill plates , support posts, beam ends in concrete beam pockets ) need to be PT .( or a barrier like a asphalt shingle or Vycor deck shield wrap around them to seperate /protect the wood from drawing moisture out of the concrete.)

  It sounds like your talking about interior floor joist with vented crawl space .  So PT should not be needed /required .  (Except for your sill plates)  Good luck  :)HTBH ;)PEG

[Jimmy C.]

I had the same problem trying to decide between untreated or treated lumber for my foundation.
The extra cost of the Pt wood was a big concern.

Due to the fact that I was building the foundation through the summer I can only work a little at a time each weekend before I start to get dangerously hot- (Last weekend it was 105 in the shade). I decided the Pt would be my best bet due to being exposed to the weather for several months of North Texas heat.

[Amanda_931]

It's possible that carpenter bees are a bit less likely to find homes in PT.  Not sure, and probably not for the expected life of the building.

Around here, I think we'd prefer 18" off the ground to non-PT framing wood.  

Don't know what the advice is if you have the Taiwan termites.