Vertical Openings (Mechanical)

[ecf1618]

The project I am working on is a hospital (I-2 occupancy) that is fully sprinklered. The hospital was built in 2004. We are adding a two story addition to the back of the hospital. I am trying to find in the code where it talks about how to handle a vertical chase ratings. I have been searching all through section 8.6 in 2016 life safety code and I don't get a clear answer. This is what we have: On the lower level we have an air handler that is getting its outside air by chasing up through the first floor with a 10" diameter pipe and out the roof above. I also have a mechanically powered vent (6" diameter) for an electrical room on the lower level that also chases up through the first level and out the roof (10ft separations from any intakes).

What I would like to know is once I put a fire damper at the first floor where the pipes are penetrating to achieve the 2-hour required separation do I need to rate the chase walls that surround it as it go up through the first level and to the roof? Do the walls need to be rated since we are essentially stopping the fire from coming to the first floor by using a fire damper at the floor? I am not sure I cant a place in the code where it talks about this.

Thanks for any help!

 

[cda]

So are you designing to IBC also?

Or just 101?

 

[ecf1618]

I would be designing to which ever is more stringent.

 

[JBI]

NFPA 101 is not a document I am familiar with, but in the IBC you would look in Chapter 7 for fire resistance rated construction. 712 for vertical openings, 713 for shaft enclosures, 714 for penetrations and 717 for ducts and air transfer openings.

 

[ADAguy]

Interesting question, is design build allowed for hospitals in your state?

 

[steveray]

If you are protecting the duct with a damper, and you are talking about 2 stories, basically you would treat it like any other single floor penetration and it is fireblocking.....The damper "protects" the opening, and you protect the annular space. If it were dryer ducts where you didn't or couldn't have dampers, it would have to be in a rated shaft...

 

[Francis Vineyard]

The project I am working on is a hospital (I-2 occupancy) that is fully sprinklered. The hospital was built in 2004. We are adding a two story addition to the back of the hospital. I am trying to find in the code where it talks about how to handle a vertical chase ratings. I have been searching all through section 8.6 in 2016 life safety code and I don't get a clear answer. This is what we have: On the lower level we have an air handler that is getting its outside air by chasing up through the first floor with a 10" diameter pipe and out the roof above. I also have a mechanically powered vent (6" diameter) for an electrical room on the lower level that also chases up through the first level and out the roof (10ft separations from any intakes).

What I would like to know is once I put a fire damper at the first floor where the pipes are penetrating to achieve the 2-hour required separation do I need to rate the chase walls that surround it as it go up through the first level and to the roof? Do the walls need to be rated since we are essentially stopping the fire from coming to the first floor by using a fire damper at the floor? I am not sure I cant a place in the code where it talks about this.

Thanks for any help!

Unless your AHJ provides an exception for I-2. Section 717.6.1 is replicated in Section 607.6.1 of the IMC (based on the 2012 & 2015)

717.6.1 Through penetrations. In occupancies other than Groups I-2 and I-3, a duct constructed of approved materials in accordance with the International Mechanical Code that penetrates a fire-resistance-rated floor/ceiling assembly that connects not more than two stories is permitted without shaft enclosure protection, provided a listed fire damper is installed at the floor line or the duct is protected in accordance with Section 714.4. For air transfer openings, see Section 712.1.9.

 

[Francis Vineyard]

I believe the below illustrates steveray's exception;

 

[ADAguy]

Nice clarification Francis, but is "is" an I-2, so then what?

 

[steveray]

I think I missed where it was a 2hr floor....and the I2 does throw a bit of a monkeywrench in it too...

 

[ADAguy]

That's why I asked the ? earlier, is this a design build and don't you have a separate agency that oversees healthcare construction or is it delegated to local AHJ's?

 

[Francis Vineyard]

Still needs to rate the chase walls in accordance with 713 and terminate the bottom of the shaft with one of the methods in 713.11


717.6 Horizontal assemblies. Penetrations by ducts and air
transfer openings of a floor, floor/ceiling assembly or the
ceiling membrane of a roof/ceiling assembly shall be protected
by a shaft enclosure that complies with Section 713 or
shall comply with Sections 717.6.1 through 717.6.3.

 

[ecf1618]

thank you Francis for the replies. i believe your last comment is for horizontal assemblies and not vertical assemblies. as others have mentioned I am looking for when it is an I-2 occupancy.

 

[ecf1618]

Interesting question, is design build allowed for hospitals in your state?

Yes it is but the hospital we are working with is required to have multiple bids when the construction cost goes above a certain threshold. So we are design-bid-building this one. For the record I prefer design-build without a doubt.

 

[ecf1618]

If you are protecting the duct with a damper, and you are talking about 2 stories, basically you would treat it like any other single floor penetration and it is fireblocking.....The damper "protects" the opening, and you protect the annular space. If it were dryer ducts where you didn't or couldn't have dampers, it would have to be in a rated shaft...

thank you for your feedback. so you would not rate the vertical shaft (from floor to underside of roof) on the second floor? Can you show me in the code where it says that? I would need to prove it to others here in the office.

 

[steveray]

Can you show me what code you are working with? Not going to be much help on 101, but specific year of IBC would work....I think the "other than I2" has you kind of over a barrel or shaft as the case might be in IBCland...If it only connects the second story through the roof, you are good, but if it connects 2 stories, IBC does not allow for I2 and 3

 

[ecf1618]

working with IBC (2012) and NFPA 101 (2015). i havent really found anything that surmounts the "717.6.1 Through penetrations" part of the code. Let me know if you find something else.