New York - Required Wall R-Value

[Kevin Hogan]

I'm renovating a building and took down some of the plaster walls. There is no insulation so I am required by code to add it. I am going by Chapter 4 of the 2015 International Energy Conservation Code. (Please let me know if this is the wrong one for New York State - not City).

I see that for my zone I need R13 for 2X4 walls plus R10, which is continuous foam board insulation on the outside. I'm not taking off the siding, so am I expected to meet the required R23 by using spray foam? That is the only way I see I could do it. Or, because I am not removing the outside siding do I only have to meet the R13 requirement. Based on the updates that I am doing I am assuming I am in the Alteration category. My code enforcer is not forthcoming with questions. He indicated I should ask a design professional. Any assistance you can provide will be appreciated.

 

[steveray]

Usually you just fill the cavity...On existing stuff. Newly constructed walls or just tore down the plaster?

Look at 101.4.3......

Exception: The following need not comply provided
the energy use of the building is not increased:
1. Storm windows installed over existing fenestration.
2. Glass only replacements in an existing sash and
frame.
3. Existing ceiling, wall or floor cavities exposed
during construction provided that these cavities
are filled with insulation.

 

[JBI]

Kevin,
Welcome to the forum.
I notice you are a NYer, and I am guessing your project is NY also.
For an existing building you would start with chapter CE5 or RE5, depending on whether it is a commercial building or a residential building (see definitions in the NYS Energy Code Supplement), unless of course if you are talking about an existing Residential Code Building, in which case you would use Appendix J of the Residential Code as amended by the NYS Uniform Code Supplement (NYS has replaced Appendix J of the IRC in its entirety, see chapter 2 of the Uniform Code Supplement).
As far as Chapter 1 in any of the adopted I-Codes, NYS replaces chapters 1 via the supplements as well.
Generally speaking, for an existing un-insulated wall the requirement is to fill the exposed cavities with any insulation that is at least R-3 per inch, this would include fiberglass batt or any type of foam insulation.

 

[mark handler]

What climate zone are you in?