What is a 1hr, 2hr, and 4hr fire wall. I always thought a 1 hr is 5/8 rock on each side of stud. I also was wondering how many electricians out there keep a copy of the uniform building code on hand or found it worth purchasing.

Seattleman, there are literaly hundreds of different assemblies for these ratings.

Go here https://www.electrical-contractor.net/ubb/Forum18/HTML/000021.html

and try the link at the bottom, If you take the assembly listed on an architects drawing you can find how it's constructed on the UL page, or you could buy a set of the orange books.

Roger

First of all, it would not be wise to purchase the uniform buidling code, since nobody uses it anymore. A copy of the IBC might be more worthwhile, but it depends on your state.

There are many, many, many ways to create fire-resistance rated walls. The most common is (1 HR) 5/8 type X gypsum baord nailed on 7" O.C. with 6d cooler nails, joints staggered and treated. Two hour...same but two layers. Three hour...same but three layers. Four hour....masonry.

Again, these are just a couple of the hundreds of ways to achieve a rating.