NFPA Running Exhaust through Firewall

[Nick Gromicko]

THAT IS NOT WHAT WE DO. We identify, and refer. Under this circumstance, we should not be advising

But it is what I do. Commercial properties are my thing and I get asked for advice about commercial buildings every day of my life.

[cfuoco]

Nick.... I have run into this situation before and doing what you said was enough to please the inspector.

Dylan... I think this is a good suggestion for John to present to the inspector. I do not think Nick would actually expect hime to do it without checking with the inspector. It is just a suggestion of a remedy.

[Nick Gromicko]

Carmine writes:

Nick.... I have run into this situation before and doing what you said was enough to please the inspector.

Thank you.

[cmcdonald]

Originally Posted by gromicko

This is nothing ingenious. It's done regularly on ranch homes out east. The bedrooms in a ranch-style home are often above the garage. The heating supply ducts to the bedrooms often run up against the ceiling of the garage perpendicular to the joists (and so are below the ceiling of the garage). A drywalled chase is built around the duct so that the space INSIDE the chase becomes part of the bedrooms (for firewall purposes) not the garage any longer, even though the chase is below the garage ceiling.

However this is not a "ranch-style home" nor are we dealing with heating supply ducts. We are, however, dealing with ducts that get laden with grease and at which time can become easily ignitable. By penetrating the fire wall you create a way for a potential fire to migrate from one portion of the building to another which, had the wall not been penetrated, would not have been present.

I realize that this does not take into account the other safety measures that would be present (sprinklers, fire dampers, and so on) however the idea behind the original subject (kitchen duct passing through fire wall) is to not penetrate the fire wall so that products of combustion can not easily pass from the kitchen side to the opposite side of the fire wall should those other safe guards fail.

[Nick Gromicko]

I'll say it one last time. There is no penetration of the firewall using my suggestion. That's why it complies with NFPA.

[Nick Gromicko]

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.

[Michael Larson]

I see no problem with Nick's solution.

The firewall is maintained with the chase.

You are simply moving the firewall.

[Nick Gromicko]

Michael writes:

I see no problem with Nick's solution.

The firewall is maintained with the chase.

You are simply moving the firewall.

Thank you.

[Darrell B. Hadler]

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.

[Joe Farsetta]

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.

[Larry D. Kage]

Originally Posted by mlarson

I see no problem with Nick's solution.

The firewall is maintained with the chase.

You are simply moving the firewall.

Exactly...done the same thing before...no problem.