Here, let me try it this way to see if you can get your head around it.
Run most of the vent and build the entire drywalled chase around it in the garage first.
Then, after it is all done, pop through from the bakery into the chase.
Where is the firewall penetration? There isn’t one.
I see no problem with Nick’s solution.
The firewall is maintained with the chase.
You are simply moving the firewall.
Michael writes:
Thank you.
Seen it done many times…always passes inspection. It’s the same as moving the entire firewall and rebuilding it 8 or 9" into the garage, which would be a complete waste of garage space? As long as the vent is enclosed with the appropriate fire rated product…it is the firewall. The problem occurs when they run the duct through an existing firewall and DON’T cover it up with a new firewall. Simple solution.
I agree with Nick. The purpose of the Code is to provide a minimum level of protection to like and property. The intent is to NOT arbitrarily be restrictive.
As to the design principal Nick eludes to again he is correct in his assertion that the firewall is merely extended to INCLUDE the ductwork. He is also correct with this design implementation is some residences.
The bottom line is whether the Building Inspector accepts it. The inspector may be required to ultimately approve an alternate design.
Exactly…done the same thing before…no problem.
Are you talking about a true “firewall” to separate into two distinct buildings, or is it one building, same lot, same owner, separating the two “uses” from each other (within one "building) for fire safety/ code requirements. If the latter is true, then you can use a fire damper connected to the building fire alarm system to penetrate the wall. If the first is true (two separate buildings), then you would need to 1.) get permission from the owner of the adjacent building if you may utilize that space, in writing 2.) rewrite the deeds of the two properties to include a utility easement to run through the property and file them with the city records department and 3.) propose a building code variance to the city which would allow you to penetrate the fire wall. My recommendation for this would be to install a fire damper on the kitchen side, appropriately rated, tied into the building fire alarm system, and additionally install a fire damper on the garage side, similarly rated, tied into the garage fire alarm system, and if there is not a fire alarm system installed in the garage, then install a fire damper with fusible link on the garage side, which would close in the presence of heat. In addition to this, the shaft created by the new duct going to the roof would need to be rated according to the building code. I imagine that it would end up being a two-hour shaft. Crazy to install two fire dampers? well, when you think about it, it makes sense, you have two buildings acting independently of each other, and each having, theoretically, two fire alarm systems, which would activate their respective fire dampers.
keep it simple, usually helps. just propose it to the city, and let them respond, and take it from there.
The Architect is the design professional of record, it should be addressed with a wet stamp drawing from them. He will have to round table the issue w/ the mechanical engineer. Submit the wet stamp drawing to the city for approval!
Ask if a fusable link damper in the exhaust would serve the intend of the referenced code.
The thread is 4 years old and long dead.