Combustible material

[Mech]

2009 IBC

In type II construction, I'm trying to convince someone that just because exterior non-load bearing walls do not need a fire rating, that does not mean using wood studs and drywall to make a fire rated wall is acceptable.

My argument is "Wood is combustible and the code says noncombustible is required, unless it is fire treated wood." Why don't we use treated wood? It's an existing building, and who knows if they used treated wood when it was built.

Any help?

 

[steveray]

603.1 #1 allows fire treated to be used in nonrated and nonbearing walls 2hrs or less....those 22 exceptions are the only places you can use combustibles in I and II construction...

 

[hlfireinspector]

I would like to say they can not use wood in a Type II building too, but, that is not what the code says. They will have to use fire resitance teated wood and they must use the fasteners that are rated for use with this type of treated wood. This cost could drive them to consider metal studs and sheetrock.As far as an existing portion of the building you can not be held responsible for things that may or may not have been code complaint when thae building was constructed.

603.1 Allowable materials. Combustible materials shall be

permitted in buildings of Type I or Type II construction in the

following applications and in accordance with Sections

603.1.1 through 603.1.3:

1. Fire-retardant-treated wood shall be permitted in:

1.2. Nonbearing exterior walls where no fire rating is

required.

​

 

[syarn]

section 703.4 noncombustibility tests (IBC 2009) provides direction to the ASTM tests (E 136) that validate a "noncombustible" material....

 

[Coug Dad]

Not that I particuallary like the idea, but......

Heavy timber is permitted in Type I and II construction by provision 16:

16. Heavy timber as permitted by Note d to Table 601 and Sections 602.4.7 and 1406.3.

One hour construction, with standard wood studs, is equivalent to HT.

602.4.6 Partitions.

Partitions shall be of solid wood construction formed by not less than two layers of 1-inch (25 mm) matched boards or laminated construction 4 inches (102 mm) thick, or of 1-hour fire-resistance-rated construction.

Therefore, a one hour rated wall with standard wood studs could be acceptable in Type II-B for walls that do not otherwise require a fire resistive rating.

 

[Mech]

Coug Dad - what printing do you have? The second and third printings apply the heavy timber exception in Table 601 to roofs, not walls. Section 604.2.6 Partitions is for Type IV construction, not Type II.

 

[Paul Sweet]

IBC 602.4 says "Type IV construction (Heavy Timber, HT) is that type of construction in which the exterior walls are of noncombustible materials and the interior building elements are of solid or laminated wood without concealed spaces."

One hour construction, with standard wood studs, has concealed spaces, so it is not equivalent to HT.