Figured I reply because I saw a few incorrect terms usage of terms.
Firewall: You generally will never see a firewall in single/two family dwellings (SFR). The intent of a firewall from a fire/life-safety perspective is to be able to treat the two buildings as separate buildings. (i.e. overly simplistic version...one side burns down and the other remains) So be carful if you are talking to a contractor because if you ask for a firewall and the contractor wants to take advantage of the situation...you will get a safer structure and a substantially lighter wallet.
Fire Retardant and Fire Resistant/Resistive/Protective are not the same. Fire Retardant generally means it's just treated to slow the rate in which it burns. Fire Resistant means it prevents the passage of heat and flame.
Also, the need for fire resistance is determined by a number of things but in SFR generally you are concerned with protecting the occupants from a fire in higher risk non-living spaces (i.e. garage) and protecting you from your neighbors and your neighbors from you. Thus, in an attached garage situation you will see gypsum board, along with a solid (or rated) self closing door between the garage and the dwelling. For a detached garage built against the property line situation you will see fire resistant construction (1 hr) and no openings along the property line. NFPA has already been mentioned, another are the icodes https://codes.iccsafe.org/public/ and would be the International Residential Code for SFR.
Also, just because it's on the approved drawings doesn't always mean it's correct. Jurisdictions usually don't have the time/resources to go thru the drawings to the level of detail it seems people assume they do. Generally they are doing a cursory review to check to see if your design professional is doing their job and comment of the obvious errors. A common error designers/builders make is assume since the City didn't catch it and approved the drawings...then it must be right.
Well enough of my rambling...now what would I do. If I was building a garage for myself I'd go gypsum board and in addition to the required fire blocking (which I'd request be at constant height) I'd also specify two (maybe even three in some places) lines of 2x flat blocking at two heights around my garage. Since I often do a bit of welding/cutting/grinding, being able to control/minimize fire is a primary concern. This would give me known anchorage points through my garage. Of course I don't have the money or the land for an RV garage...so I can only dream.
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