§110.1 · Mandatory measures (general)

# §110.1: Mandatory measures (general)

What it requires

Title 24 §110 sets the "mandatory measures", minimum specifications that every residential building has to meet in California regardless of whether the project uses the prescriptive package (§150.1(c)) or the performance compliance path. They are non-negotiable: a performance trade-off cannot buy you out of a mandatory measure.

The §110 mandatory set covers:

• Equipment efficiency floor values (HVAC, water heating, pool heaters).
• Pipe insulation thickness for hot-water distribution.
• Fenestration certification, every window and skylight ships with an NFRC label.
• Air-leakage testing for ducts.
• Lighting controls (vacancy / dimmer / dimming requirements in specific rooms).
• Joint Appendix references for measure-by-measure construction quality.

When it applies

Every project. Newly constructed homes, ADUs, additions, and alterations all ride on top of the §110 floor.

How we use it

When you confirm the project on the Confirm step, we resolve the mandatory floor for your scope and pre-fill it on the design options. You can see the mandatory minimums on each of the three design cards.

Common gotchas

• Equipment models that meet §150.1(c) prescriptive numbers but not the §110.1 mandatory floor for the equipment category, the floor wins.
• Light-fixture types that the architect's lighting plan calls out but that don't carry the §110 vacancy / dimming controls required for the room they sit in.
• Hot-water distribution that meets the recirc requirement but skips the pipe-insulation thickness mandatory measure.