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2009 IRC Energy Code for Ceilings Inspector Disagreement

RyanBuilder

Registered User
Joined
Apr 9, 2018
Messages
11
Location
New Hampshire
Hello All,


I'm hoping an expert can chime in with definitive proof of what is correct on a disagreement I’m having with a local building inspector. I’m building a home in a NH city and the inspector is requiring R49 for the flat 2nd floor ceiling with an unconditioned attic above. The code reads that R38 is allowed wherever the full height of uncompressed R38 extends over the wall top plate at the eaves, which it does (R402.2.1). I’ve pointed this out to the inspector and he said that is an exception that he must approve first. He also mentioned that there is a local city ordinance that changed the city’s climate zone to zone 6 instead of zone 5 where it is listed in the code book. I can’t see how this has any bearing since the zone 5 and 6 insulation requirements are the same(R402.1.2). Can anyone clarify?

The other issue we are having is that our heating ductwork is in the 2nd floor ceiling joists with R8 insulation. The inspector said we must move the ductwork above the attic subfloor or insulate the roof line and make the attic a conditioned space. He will not let us have any ductwork in the insulated ceiling. We have done this many times in other towns and cities with no issue. I’ve talked with other inspectors and they say it is allowed although I don’t know where in the code. Does anyone know for sure?

Thanks,
Ryan
 
I would first ask him for a copy or a link to the local ordinance. If it calls out R-48 then he wins. If not you can talk to who ever is in charge of the town or file an appeal. Try to be professional and not lose you cool. The second part of your question is a bite tricky. I suggest rather than insulating the entire attack/ roof you propose to insulate the bay that has the duct and a bay on each side to the required R value. Think of it like creating an insulation blanket over a sprinkler line if you understand that.
 
R48: It's probably not worth the energy it will take to argue about the energy it will save. Just do it.

The duct in the ceiling joist is worth the argument it will take and there is no obvious benefit.
 
I would have thought this was obvious- but the IRC 2018 N1103.3.6 codifies it.
https://codes.iccsafe.org/content/IRC2018/chapter-11-re-energy-efficiency.
See page 15-https://www.nahb.org/Products/35488__Significant%20Changes%20to%20the%202018%20International%20Residential%20-%2035488.aspx?code=35488
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