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2018 Energy Code

my250r11

Sawhorse
Joined
Feb 16, 2015
Messages
880
Location
Roswell, NM
I'm looking for more compliant ways or see if there are more compliant ways than what we came up with to meet the 2018 energy code in a 3B climate zone. Any help would be appreciated. As usual contractors are pushing back on our suggestions so I'm looking to see if we missed any prescriptive compliant assemblies. Thank for your help in advance!!
 

Min&Max

Silver Member
Joined
Oct 29, 2009
Messages
321
Location
Nebraska
I'm looking for more complaint ways or see if there are more complaint ways than what we came up with to meet the 2018 energy code in a 3B climate zone. Any help would be appreciated. As usual contractors are pushing back on our suggestions so I'm looking to see if we missed any prescriptive complaint assemblies. Thank for your help in advance!!
Well you either dork around with ResCheck or you use the prescriptive method. Or you can do what I did. I amended the entire chapter dealing with residential out and wrote our own single page energy code.
 

my250r11

Sawhorse
Joined
Feb 16, 2015
Messages
880
Location
Roswell, NM
Well you either dork around with ResCheck or you use the prescriptive method. Or you can do what I did. I amended the entire chapter dealing with residential out and wrote our own single page energy code.
I wish we could. The Code is State adopted and we can only be more strict. None of our local guys are going to have rescheck. We don't either and good luck on getting the chip counters to get it for us. The R-20 in the walls with 2x4's seems to be only a foam if they don't want to do the continuous on the outside.

With the continuous on the outside an EFIS is ok for the stucco'd look but if they want brick not sure you can find anything in manu. inst. instructions for installing brick ties to foam.

2x6 walls still only give you R-19 not 20 so lots of questions and not sure I have a good answer other than spray foam which is not very dollar friendly so contractors are barking. Hoping we are missing something but not sure we are. o_O
 

Joe.B

Registered User
Joined
Dec 4, 2020
Messages
352
Location
Arcata Ca
Don't know how true this is but someone told me that the 1/2" exterior sheathing and the 1/2" interior drywall gets you from R-19 to R-20. I buy it because R-1 is supposedly equivalent to 1" of wood. So, by that logic, if your code says R-20 and they are installing R-19 I'd say they're compliant.
 

mp25

Registered User
Joined
Jun 2, 2016
Messages
101
Location
Illinois
ResCheck is free software - web based - so no need to download it. It allows for more flexibility than prescriptive. I have done houses with 2x4 R-15 batt insulation that met 2018 IECC by raising insulation values in other components of the building

2x6 walls can give you R-20. There is high density fiberglass insulation that gives you R-21. Roxul comfortbatt comes with R-23 value in 5.5" thickness.

The prescriptive insulation values (the R-value table) only accounts for the insulation - not other building components, so adding the value of the gyp. bd. does not work with the R-table (see 1102.1.3) If you use the U-value table, that looks at the overall assembly (air films, drywall, stud/insulation, sheathing, exterior finish etc) - so going this route you would be able to get credit for those components.
 

redeyedfly

Registered User
Joined
Feb 22, 2021
Messages
230
Location
Minneapolis, MN
I wish we could. The Code is State adopted and we can only be more strict. None of our local guys are going to have rescheck. We don't either and good luck on getting the chip counters to get it for us. The R-20 in the walls with 2x4's seems to be only a foam if they don't want to do the continuous on the outside.

With the continuous on the outside an EFIS is ok for the stucco'd look but if they want brick not sure you can find anything in manu. inst. instructions for installing brick ties to foam.

2x6 walls still only give you R-19 not 20 so lots of questions and not sure I have a good answer other than spray foam which is not very dollar friendly so contractors are barking. Hoping we are missing something but not sure we are. o_O
REScheck and COMcheck are free and they're both very easy to use. Most jurisdictions require their use or some other energy modeling software.

R-21 is a commonly available fiberglass batt insulation for 2x6 walls.

If you want to add in the sheathing, etc., you can use the U value tables.
 
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