Code check

The Code check panel compares the assembly with the prescriptive insulation paths of an energy code. It shows each path for the zone with a check or a cross, then a verdict.

The check is a planning aid, not a compliance finding. The code rows in the app are still being verified. Check the table in the code yourself and have the result verified by a licensed professional.

Pick the code and zone #

In the toolbar:

• Code: IECC 2021 residential, IECC 2021 commercial or IECC 2024 residential.
• Zone: Zone 1–2, Zone 3, Zone 4A/B, Zone 5 / 4C, Zone 6 or Zone 7–8.
• Location: a preset city sets the zone for you, along with the winter outside temperature. Pick Custom… to set things by hand.

Some zone choices group several code zones. Where those zones' rows differ, the check uses the stricter one.

Use the project's site #

When the assembly is in a project whose page has a location, ◎ Use project site appears in the toolbar. It finds the nearest weather station and sets the outside temperature from it. The zone stays the project's own when the project has one. Otherwise it comes from the station, and the tool asks you to check the county map.

Which column the check uses #

The code judges wall types differently, so the check first decides what kind of wall it is. The panel says which, like Wood-frame wall → followed by the column it uses.

• Steel-frame: any steel stud bay with insulation in it.
• Mass: CMU or cast concrete, with no insulated framing.
• Wood-frame: everything else.

Floors use the code's floor rows.

How each path is judged #

• Wood-frame walls: the rated cavity R and the continuous insulation (ci) R must each meet the path's numbers.
• Steel-frame walls: the residential codes use the U-factor alternative, so the effective U must be at or below the path's U. The commercial code uses rated cavity plus ci, like wood.
• Mass walls: in the residential codes, cavity and ci together must meet the path's first number, or its higher second number when more than half of that insulation is on the inside of the mass. In the commercial code, the ci must meet the path.
• Floors: cavity and ci together must meet the minimum.

The assembly passes when any one path passes.

The verdict #

• Meets a prescriptive path for this zone.
• No prescriptive path met — add cavity or continuous insulation.
• This table has no rows for this assembly in the app — check the code directly. This shows, for example, for a floor under the commercial code, which the app doesn't tabulate yet.

Under the verdict, the panel says how far the rows have been checked against the code book, lists notes on how the zones are grouped, and links to the code section.

Assemblies saved with the older check #

An assembly saved before the current check shows Saved with the older check. It's still judged the way it was when it was saved: every wall on the wood-frame column, with stud bays estimated from their depth.

To move it to the current check, click Update to the current check. Then pick the real product in each stud bay. Old values show as "saved estimate" until you do. The verdict may change.

The vapor retarder rule #

The separate Vapor retarder check sits under the dew point results. See Dew point and vapor.

Related #

• R-values and U-factor
• Dew point and vapor
• Layers and materials