I have this bookmarked in my notes re: Condo/Townhomes:

"Single-family dwellings, two-family dwellings, and multiple single-family dwellings (townhouses) are covered by the International Residential Code (IRC).

The IRC defines a townhouse as “A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with open space on at least two sides.” We have found some building officials are allowing two-unit townhouses with separate ownership and property lines dividing the two attached units.

IRC R317.2—Townhouses further states each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies of not less than one-hour fire-resistive-rating with exposure from both sides for exterior walls with a fire separation distance less than three feet. By exception, a common 2-hour fire-resistance-rated wall is permitted for townhouses if such walls do not
contain plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. (Note: Proposed Amendments to the IRC may allow the fire-resistance rating of the common wall to be reduced to 1-hour provided the building is equipped throughout with an automatic sprinkler system and the common wall does not contain plumbing or mechanical equipment, ducts or vents, and electrical, cable, and telephone installations are installed in raceways and metallic outlet boxes.)

All multifamily dwellings (apartments, condominiums) are covered by the International Building Code.

(IBC). The IBC does not differentiate between condominiums and apartments; they meet the same building construction requirements. Both fall under IBC 310.1-Residential Group R-2 as residential occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanent (non-transient) in nature. Typically, walls separating R-2 occupancies shall have a fire resistance rating of 1-hour (½-hour if the building is equipped throughout with an automatic sprinkler system)."

- http://www.lni.wa.gov/TradesLicensin...ts/Elc0611.pdf

And have this thread bookmarked with regard to townhouse/condo IBC/IRC differences, "Next By Subject" steps you through the discussion:

http://www.kcmo.org/codes/ibs/IB142.PDF

I have to read stuff about once a year to keep it straight - I really wish someone with a more complete understanding than my own would write an article setting all this out in one place.