Demising Wall in Existing 1 story building Questions

[palikona]

I'm working on a commercial TI project in an existing 9,000sf 1 story building with a gable roof. There is an attic space above with wood trusses. There are vented eaves and an open ridge with 4" shingle over ridge vent. Currently, there is a single tenant in the space and the plan is to subdivide the building into two tenant spaces and a new 1 hour demising wall will be provided. The wall will need to go up into the attic space up to the sloping roof sheathing. Do I need to do anything at the continuous ridge vent to assure the continuation of the fire rating to the top of the roof? Fire caulk or mineral wool? Do I need to do something similar at the continuous eave venting? Thank you!

 

[steveray]

Why are you putting in a 1 hour wall? You don't need it...

 

[palikona]

The AHJ says we do. What am I missing? Maybe he's concerned in the future the other space could be a different use?

 

[walker.t]

the plan is to subdivide the building into two tenant spaces and a new 1 hour demising wall will be provided.

Any chance the plans reviewer is thinking this is a open mall building? That would require separation per IBC 402.4.2.1.

Maybe he's concerned in the future the other space could be a different use?

I doubt that, the use and occupancy of pretty much any tenant space is subject to change in the future. It would be like them turning down a plan because you have X number of toilets and they give you a review comment that says, “Double number of toilets in case the occupant load increases when a new tenant moves in.” You could put in provisions for possible future changes if you wanted (like an extra stair, extra exits, extra toilets, et cetera) but that’s at the building owner’s discretion.

 

[palikona]

I thought every tenant space in a commercial building needs a rated demising wall, especially when there's no sprinkler system?

 

[Yankee Chronicler]

I thought every tenant space in a commercial building needs a rated demising wall, especially when there's no sprinkler system?

It depends on the use/occupancy of the two tenants. See IBC Table 508.4. For example, two B tenants, two M tenants, or one B and one M tenant don't require a rated separation. Make one of the two tenants into an assembly use (bar or restaurant, for example) and now the demising wall needs a 2-hour rating.

 

[steveray]

Make one of the two tenants into an assembly use (bar or restaurant, for example) and now the demising wall needs a 2-hour rating.

Depends on the size of the building....

 

[steveray]

The AHJ says we do. What am I missing? Maybe he's concerned in the future the other space could be a different use?

Did the AHJ give you a code section? Dealing with this on a refit of an A2 into an M/ 2 other tenants to be named later building and really wondering why people have been bullied into this to the point where it has "become code"...