Jeff,

Just what is certified property anyway?

Seriously, the shrinkage you are concerned about shouldn't be a significant factor. Wood changes size significantly from green (fresh off the stump) due to the loss of bound water within the wood cells. The water that enters the wood due to high moisture in a crawlspace will do little to change it's volume.

How brittle the wood is is both a function of the properties inherent to the species of wood your joists were milled from, and the effect of fungus (in the form of mycelium) that has been able to propagate due to the high moisture conditions. Eliminating the moisture will do a lot to stop the fungus that may be present, but a good anti-fungal treatment would ensure it'd demise.

I would recommend a product called Bora-Care be applied (2 gal. sprayer) to the joists and sills. This product is a refined borate material in an ethyline glycol base. Not only will it work to eliminate the fungus, it will remain in the wood relatively impervious to future moisture fluctuations. It will also be very beneficial at the interface with the stone foundation.

Of course, if the wood at the foundation is already rotted, borate treatment won't bring it's strength back. My method for checking for rot is to tap the wood with a wooden mallet. If it is sound it should "ring". If it's dody it will "thud". You can also try driving an awl or ice pick into the wood. It will penetrate easily if the wood is bad.