Do any of you mention it if you have a house built prior to todays date that does not have pressure treated lumber being used as the sill material if it sits directly on concrete?
Do you know what year the IRC brought this into play?
Thanks,
Look at NFPA 58
Many times I dont even get to SEE the sillplate. 
And many times, the sill is not PT.
It depends on the year the home was constructed. Before getting into the IRC, remember that the local building inspector is the AHJ, and if he blessed it, it can be nothing more than a “concern” on your part.
Millions of homes were constructed without the benefit of PT lumber as a sill. Keep this in mind.
Scott, It was required in IRC 2000 if that helps you.
http://www.wwpinstitute.org/treatedwoodnews/Jul04%202000%20IRC%20on%20Jul%209.pdf
and here;
UBC1997Section 2306.4A motion was passed to require pressure treated sill plates in both interior and exterior applications as required by UBC Section 2306.42001 - Requirement For Pressure Treated Sill Plates9/12/2001
Hope that helps.
Lack of P.T. sills in a dry environment, would not concern me much, and like Joe indicated, the AHJ has gone through and approved it at one time or the other. Dampness, rot, and signs of decay would be a different situation.
Marcel 
Woods which are naturally decay resistant are also acceptable as sill plates under the IRC, provided that the woods are all heartwood.
And…keep in mind that concrete has more moisture than wood sill plates and it can rot quite easily without the dividing material.
I hazard to think of how many pt sill plates were installed without galvanized or coated nails. The new pt will eat through non coated nails in short order and then we will have a ton of free floating walls. I have spoken to many contractors who did not know this.
Larry
Many new homes here have engineered lumber for bottom plate.
From today’s draw inspection…
That has to be the Denver area, with the plate perched up on those spikes…