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Vestibules: IECC vs. ASHRAE

jeremy

Member
Joined
Oct 19, 2009
Messages
8
Location
Texas
I was just curious how others handle vestibules in commercial spaces over 3,000SF. There is a big difference between the requirement for a vestibule in the IECC versus ASHRAE 90.1. IECC requires them in any space over 3,000SF while ASHRAE typically only in buildings 4 stories or more. I'll be honest in that I don't always enforce the vestibule requirement if someone is using the IECC for energy compliance. Someone will submit a COMcheck using IECC with their permit application for a project that technically needs a vestibule, but all they have to do is change it to ASHRAE 90.1 and they don't need one. Nothing will have changed on the doors, windows, insulation, etc. otherwise. It's just that one code requires it, and the other doesn't. I could have them resubmit their COMcheck under ASHRAE, but it's just a waste of time for basically what amounts to a technicality. So again, I was just curious -- how do you all handle vestibules?
 

north star

Sawhorse
Joined
Oct 19, 2009
Messages
4,090
Re: Vestibules: IECC vs. ASHRAE

jeremy,

In Section 107.2 OF THE `06 IECC: - CONFLICTING REQUIREMENTS.
"Where the provisions of this code and the referenced standards

conflict, the provisions of this code shall take precedence."

We would go with the IECC requirements.

.
 

TJacobs

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Oct 19, 2009
Messages
1,362
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60102
Re: Vestibules: IECC vs. ASHRAE

If you read both documents, and I encourage you to do so, you will find it is not that simple. While it may seem easy to just use a different code to prepare a COMcheck, there may be other more restrictive provisions within ASHRAE that not only you were not aware of but neither is the DP. One or the other, you can't mix and match.

I do not like the IECC permitting ASHRAE to be used but it is what it is. It's like the IBC saying you can use the IBC or NFPA 5000 instead.

I would suggest that the IECC Commercial becomes the more-stringent amendments to ASHRAE, and the IECC Residential is copied word-for-word into an IRC chapter so the IRC can again be a stand-alone book.
 

Gene Boecker

Gold Member
Joined
Oct 19, 2009
Messages
746
Location
Saint Louis, MO
Re: Vestibules: IECC vs. ASHRAE

The part that I like is that a building construction provision, affecting the general layout of a building, is hidden in a technical code rather than being in the building code. Even the plumbing provisions have been copied into the IBC for ease of use.

I gotta write a code change!

(Remind me to do that in another two years.)
 

Lou Marks

Member
Joined
Oct 25, 2009
Messages
28
Location
Hampton, Va
Re: Vestibules: IECC vs. ASHRAE

Actually there is no conflict between the two standards. If you use ASHRAE 90.1 then the design must be engineered and sealed. If you use the prescriptive requirements of chapter 5 then if does not necessarily require to be sealed.
 

TJacobs

Sawhorse
Joined
Oct 19, 2009
Messages
1,362
Location
60102
Re: Vestibules: IECC vs. ASHRAE

Lou Marks said:
Actually there is no conflict between the two standards. If you use ASHRAE 90.1 then the design must be engineered and sealed. If you use the prescriptive requirements of chapter 5 then if does not necessarily require to be sealed.
Actually there is conflict between the two. Suggested reading:

http://bcap-energy.org/files/ICC_Comparison_2009-IECC_vs_2007-ASHRAE90-1.pdf

http://www.energycodes.gov/codedevelop/pdfs/90-1_iecc_comparison_final_12-16-2009.pdf
 

Lou Marks

Member
Joined
Oct 25, 2009
Messages
28
Location
Hampton, Va
Re: Vestibules: IECC vs. ASHRAE

I am quite aware there are differences between the two standards, just as there differences between the IRC and IBC. Differences are not conflicts when one is using one standard or the other. There is the benefit of using engineered method verses prescriptive..
 
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