Replacing subfloor under existing walls.

[ooftahbob]

I'm currently replacing the subflooring on the entire ground level of my home; it is on a 32 inch crawl space. I had termite and moisture damage and cannot get a bond until replacement is completed. I'm not having trouble with basic subfloor and joist but not sure how to handle replacing subfloor under existing walls. I have been told to just use shims (which I don't care for) or to use treated lumber (1 X 6 ripped down). The second idea is more appealing but more difficult. Any ideas please.

[pushkins]

Is the sub floor under the wall damaged enough to need repair, sagging walls etc...?
Most often this is done by removing half on one side of the wall, replacing subfloor and then proceeding to remove the other half on the other side, this way the wall is half supported at all times. Ceiling/upper level loads still need to be supported while your doing this work.
Load bearing walls are much more difficult, ultimately you need to support the above load before removing the existing subfloor under the wall. This is usually done by installing all new subfloor up to about 2' out from the wall, then build a temporary support for the above loads on the new sub floor, once supported then removing the existing sub floor and replace with new.
On top of what I mentioned above you need to make cut outs for any plumbing or electrical work coming up through the bottom plates of the walls.
You can shim under the wall between the joist and bottom plate as you remove the sub floor however this means that you then need to notch the new sub floor material around the shims and then seal any gaps.

Treated or standard lumber ripped down to be the same size as the existing sub floor or treated ply the same size (my preference) is a good option as you can slip it in under the wall often from one side pushing out the damaged sub floor as you push it in, obviously you need to remove exposed sub floor from either side of the wall first. Then replace the remained of the floor cutting to fit.
Another problem is the nails used to attach the bottom plate to the flooring, your going to have to cut these off, make sure you re nail the bottom plate back down once finished, this wall may well move while your repairing the floor, so level it back before nailing.
Are the walls open or clad in drywall?

There are many, many more things to be careful for when doing sub floor replacement, the number 1 thing to always remember, never remove sub floor from under a wall without a support system in place for above loads. Plus the support system can also be adjusted to actually lift (ever so slightly) the wall, this will make the task easier as well.
I use lally posts (steel adjustable posts with a threaded section at the top) along with either a 4x4 or two 2x4's nailed together (used side on) spacing of the posts will depend on what your above loads are and how long the wall is your working on.

[ooftahbob]

Replacing subfloor under existing walls.

Thanks for the suggestions.