Fire Blocking - 100 year old gutted home

#1 You need to go back and add your location to your profile, Yes it make a differance where you live.

Here the way I do it, I add solid wood 2X's at the top and bottom of the walls. Any place there's gaps or a notch where a wire goes get filled in with high heat caulking for the small gaps, and expanding high heat foam on the big gaps.
I also add blocking along the middle of the wall.
Those old 2X's are going to be wider then a new 2X so your going to have to rip 2 X 6's or just add whatever thickness spacer you need.

A few things to concider.
Adding house wrap (Tyvek) between the wall studs to cut down on the drafts.
Getting rid of all that old steel pipe before it starts leaking.
Building the studs out so you can fit more insulation.
http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table

The very best way if you can afford it is to use foam not batts.

Boy does this bring back memories! I always wondered about the guys that hand nailed all that plaster lath in place, man what a PIA, Huh? Here are a few things you are going to run in to. Studs out of alignment. They put that lath on and trued up the walls with brown coat. I bet yours had horse hair in it right? I had to sister 2x6's to some walls they were so far out, and used string lines for plumb.

Joe is correct re the piping, get it out NOW. In NJ in a lot of towns you have to use copper. Use min type L. Not M.

As far as the fire stopping, make sure you talk to the BI, and do what they say. many of the small towns in NJ have their own rules, and its easier to comply than try to buck. I would use fiberglass Bat, if I were you, and a poly vapor retarder on the studs, under the drywall, this will help a lot with drafts and moisture migration. When foam burns it produces cyanide gas and will kill you fast. It can also leach chemicals for years, and cause all kinds of allergic reactions. Watch out for Asbestos, You will probably run into it somewhere. If you do, PM me and I will help you be rid of it safely.

Hopefully you have a nice table saw to rip with. Good luck.

In taking apart this house I wonder about a lot of things, mostly how it is still standing! Now that everything is out I believe that I am going to start a project showroom peice to keep everyone updated and so that I can get advice regularly.

Thanks for the responses. The walls are suprising true, but i am sure that i will need to true them up at some points. The Piping is actually unconnected old gas lighting piping (small piping).

The other two pipes are radiator piping and are being moved as that exterior wall is coming down. I will have a plumber do this so whatever he puts in has to meet code so we will see. I will be taking out a bunch of walls so I will have some "real" 2x4's to work with when blocking. I know that the blocking will help to some degree, but this whole house is made of 100 year old dried wood, basically kindling so I feel like this will be a wasted effort. I guess whatever code is I will certainly have to meet it.

You dont happen to be/or know any good insulation guys in the Haddonfield area do you? I need some spray foam done in a particular area of the house to try to get my R-30 in a ceiling that I do not want to build out too much.

All of the above. Already removed all the knob and tube (5 out of 12 circuits). Removed all of the trim (to be put back up later). Also have had structural engineer in for my structural work. We have to 1) jack up the house and resupport the main center beam 2) reinforce by sistering the 1st floor main beam to hold up the 2nd and 3rd floor (currently 2- 2x 6's). We are taking out the old exterior of the home to open it up into the kitchen and den. (about 18ft of the old exterior). And finally we have to build a new header where they just notched studs of the old exterior for the new and improved entranceway. They also notched all the old floor joists in the 2nd floor for plumbing so we have to remove the plumbing and rebuild that. All of which I have sketches for. Should make for a fun Christmas break.

The only reason i may need to put in foam in a small section of the house (kitchen addition) is b/c the rafters are 2x4's. It is a vaulted ceiling going from about 12ft down to 8. If i build up the rafters I may be looking at to low of ceilings at the 8ft end. Cabinets will be here so I really do need all 8 ft. of ceiling. Everywhere else in the house will be batt insulation as I have adequate space. Not as much as I would like but enough to meet code.