Treated Wood Question

[snowocean]

Looking at wood blocking specifically and what is required per section 603. Have (3) locations to consider:

Exterior
Interior in Rated Walls
Interior in non-rated Walls

I believe section 603.1-1.1 and 603.1-1.2 require the exterior and interior walls to be fire-retardant-treated, but then I see 603.1-14 and am wondering if I can simply use untreated wood everywhere........assuming sections 603.1-1.1thru 603.1-1.3 are referring to the framing only.

 

[steveray]

No requirement for blocking to be FRTW.....

 

[classicT]

Section 603 Combustible Material in Types I and II Construction

603.1 Allowable Materials

Combustible materials shall be permitted in buildings of Type I or II construction in the following applications and in accordance with Sections 603.1.1 through 603.1.3:
...
Exceptions:

...
14. Blocking such as for handrails, millwork, cabinets and window and door frames.​