Intersection of fire partitions

[Codegeek]

View attachment 2129

I have an R-1 use, Type VA construction. My question has to do with how do you deal with intersecting fire partitions. We have a corridor, which is a fire partition, and a wall that separates two guestrooms, which is also a fire partition. We've detailed it as in the attached in blue, the AHJ wants it to be detailed as noted in red. I can't find any language in the IBC to address this situation nor are there any illustrations in the commentary to address it. Does anyone have any insight on this?Thanks for the help.View attachment 2129

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[steveray]

If the drywall in the "top" wall is not continuous, the rating probably is not either....Although if it is sprinklered and 20 min rating I can't imagine it would actually matter..If you can find a listed wall assembly with the stud there, you are good...Don't forget the STC rating...

SECTION 1207 SOUND TRANSMISSION

1207.1 Scope. This section shall apply to common interior walls, partitions and floor/ceiling assemblies between adjacent dwelling units or between dwelling units and adjacent public areas such as halls, corridors, stairs or service areas.

1207.2 Air-borne sound. Walls, partitions and floor/ceiling assemblies separating dwelling units from each other or from public or service areas shall have a sound transmission class (STC) of not less than 50 (45 if field tested) for air-borne noise when tested in accordance with ASTM E 90. Penetrations or openings in construction assemblies for piping; electrical devices; recessed cabinets; bathtubs; soffits; or heating, ventilating or exhaust ducts shall be sealed, lined, insulated or otherwise treated to maintain the required ratings. This requirement shall not apply to dwelling unit entrance doors; however, such doors shall be tight fitting to the frame and sill.

1207.2.1 Masonry. The sound transmission class of concrete masonry and clay masonry assemblies shall be calculated in accordance with TMS 0302 or determined through testing in accordance with ASTM E 90.

1207.3 Structure-borne sound. Floor/ceiling assemblies between dwelling units or between a dwelling unit and a public or service area within the structure shall have an impact insulation class (IIC) rating of not less than 50 (45 if field tested) when tested in accordance with ASTM E 492.

 

[jdfruit]

I have heartburn on both variations in the detail.

If there is structural wall bracing at the wall between sleeping units, then a structural intersection is required, either variation shown doesn't provide a reliable structure connection. Just normal wood framing requires a typical 3 stud intersection for stability and top plate continuity.

Having the corridor wall board continue past the joint does provide a continuous corridor wall. However, the wall separating sleeping units is also required to be fire rated 1hr which is the same fire rating as the corridor wall. If you have a 1hr intersecting a 1hr there is no penetration in the membrane, it is all 1hr. The only difference is the required F & T ratings of any other penetrations in corridor wall while the sleeping unit wall doesn't require F & T penetrating assembly ratings.

 

[Codegeek]

I have heartburn on both variations in the detail.If there is structural wall bracing at the wall between sleeping units, then a structural intersection is required, either variation shown doesn't provide a reliable structure connection. Just normal wood framing requires a typical 3 stud intersection for stability and top plate continuity.

Having the corridor wall board continue past the joint does provide a continuous corridor wall. However, the wall separating sleeping units is also required to be fire rated 1hr which is the same fire rating as the corridor wall. If you have a 1hr intersecting a 1hr there is no penetration in the membrane, it is all 1hr. The only difference is the required F & T ratings of any other penetrations in corridor wall while the sleeping unit wall doesn't require F & T penetrating assembly ratings.

There will be the three studs at the intersection. I chose not to include them in the sketch to show more clearly the sheetrock and how it was to be situated.

 

[Codegeek]

If the drywall in the "top" wall is not continuous, the rating probably is not either....Although if it is sprinklered and 20 min rating I can't imagine it would actually matter..If you can find a listed wall assembly with the stud there, you are good...Don't forget the STC rating...

Yes, we have an STC rating for the assemblies.

 

[mtlogcabin]

There will be the three studs at the intersection.

A sprinkled building with 30 minute fire rating requirements and they are wasting their time and yours on the detail for the intersecting wall.

Old school the corridor sheet rock should be continuous. Today with sprinkler trade offs and reductions in time does it really matter. The intersecting wall joint provides more protection with the wood stud backing then the horizontal joint running down the middle of the wall with no backing behind it.