2018 Energy Code

[my250r11]

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!!

 

[Mr. Inspector]

Can't give you other ways unless you tell us what you came up with to meet the 2018 energy code

 

[Min&Max]

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.

 

[bill1952]

Can you post that or a link?

 

[my250r11]

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.

 

[Joe.B]

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]

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]

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.

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.

 

[BayPointArchitect]

We require REScheck and COMcheck for all new construction. I agree that this is a tedious task that requires a few hours. But it allows the builder some flexibility to use R-19 for the walls and then compensate by over-insulating the attic. When choosing the performance-calculation route then you can dismiss the prescriptive requirements. What many contractors appreciate most about this is that they can decide whether-or-not to include rigid insulation around the perimeter trench footings. They don't mind installing the insulation on a good day. But if the REScheck or COMcheck shows zero for perimeter foundation and the performance check shows compliance, then they can go ahead and install the foundation insulation as an added bonus. But if the concrete truck shows up early on a windy day and it becomes impossible to get the insulation to stay in the trench, then they can show the passing report to the building inspector and keep pouring concrete in the trench without the rigid insulation. Energy code experts have determined that this foundation insulation counts for only 4% of the energy savings so it is not a big deal. The more you know = the more options you have.