/title-24/150.1(c)14.
Mandatory measures (general)
The baseline set of mandatory measures every California residential project must meet, applies regardless of whether the project uses the prescriptive or performance path.
Cool roof requirements
Solar reflectance and thermal emittance minimums for low-slope and steep-slope residential roofs in California's hot climate zones, and the §150.1(c) interaction that drives RB suppression in CZ10-15.
HVAC equipment efficiency (mandatory)
Federal-floor and California-floor minimum efficiencies for residential heating and cooling equipment — SEER2, EER2, HSPF2, AFUE — the §110.2 mandatory floor that no compliance trade-off can buy below.
Water heating equipment (mandatory)
The federal- and California-floor minimum efficiencies for residential water heaters — UEF by tank size and fuel — and the §110.3 requirements on isolation valves, pipe insulation, and HPWH spec compliance.
Fenestration mandatory measures
Mandatory rules for windows, skylights, and doors, NFRC certification, default U-factors when no label is available, and air-leakage limits at the unit level.
Air-leakage testing (envelope and ducts)
Mandatory air-tightness requirements, blower-door test on new construction, total-leakage and leakage-to-outside on duct systems, and the role of ECC field verification in closing them out.
Mandatory installation requirements
How insulation, fenestration, HVAC equipment, and ducts must physically be installed — the §110.8 quality-of-installation rules that take a code-compliant spec sheet and make it a code-compliant building.
Ceiling and roof insulation (mandatory)
The mandatory minimum ceiling R-value floor that every California residential project must meet, regardless of which compliance path the design takes.
Wall insulation (mandatory)
The mandatory minimum wall R-value floor for above-grade and below-grade walls, the floor that every California residence must meet regardless of compliance path.
Floor insulation (mandatory)
Mandatory floor insulation for floors over crawl space, over unconditioned basement, over garage, and over outside air — the floor under all California residential compliance paths.
Slab-edge insulation (mandatory)
When slab-on-grade construction has to carry edge insulation, how deep, and at what R-value — the §150.0(e) floor and the §150.1(c)1 prescriptive stack above it.
Door U-factor (mandatory)
The mandatory thermal-performance floor for exterior doors on California residences, and the §150.0(g) carve-out that flips a heavily glazed door into the fenestration rules instead.
HVAC equipment sizing
Sizing rules for heating and cooling equipment, ACCA Manual J load calc required, Manual S equipment selection, and the limits on how much oversizing the code tolerates.
Mechanical ventilation (whole-building and local exhaust)
Whole-building mechanical ventilation rates per ASHRAE 62.2, plus the local exhaust requirements for bathrooms and kitchens that every California dwelling must meet.
Duct insulation and sealing
Duct insulation R-value minimums by duct location, mastic-or-tape sealing requirements, and the §110.7 leakage tests that close them out.
Domestic water heating (mandatory)
Mandatory rules for residential water heaters, UEF floor, pipe insulation, demand-recirc controls, and the rules that determine when an existing heater can be grandfathered.
Duct sealing and leakage testing (mandatory)
The mandatory duct-tightness requirements on every residential HVAC system, with mastic sealing on joints and §110.7 leakage testing that closes the install out.
Radiant barrier (mandatory in most climate zones)
When a radiant barrier is required on the roof deck, which climate zones suppress it, and the special interaction with §110.10 cool-roof rules in CZ10–15.
The performance compliance path
How the performance path compares the proposed design against a 'standard design' built to the prescriptive package — and when a designer would choose it over the simpler §150.1(c) route.
The prescriptive package (overview)
The §150.1(c) prescriptive package is the default code-compliance path, a fixed set of envelope, HVAC, DHW, and PV values that change by climate zone. Meeting all of them is enough to pass Title 24 without a performance trade-off model.
Prescriptive envelope baseline (insulation by climate zone)
The prescriptive ceiling, wall, floor, and slab insulation values for newly constructed low-rise residential, the per-climate-zone numbers that the standard design lives or dies by.
Solar PV mandate
The solar PV requirement for newly constructed single-family homes and detached ADUs, required kW is computed from conditioned floor area and the number of dwelling units, with carve-outs in §150.2(a).
Prescriptive fenestration (U-factor and SHGC)
The U-factor and SHGC values every window and skylight must meet on the prescriptive path, with per-climate-zone variation that drives whether dual-pane low-E or triple-pane is required.
Prescriptive air-leakage (ACH50 ≤ 5)
The prescriptive whole-building air-leakage threshold for newly constructed residences, measured by blower-door test at 50 pascals, and verified by an ECC Rater at field inspection.
Additions to existing residences
How Title 24 treats additions to existing homes, the addition zone is modeled to the prescriptive baseline, existing equipment is grandfathered unless replaced, and the §150.1(c)14 PV mandate is intentionally NOT invoked.
Alterations to existing residences
How Title 24 treats alterations to existing homes, the component-based trigger system that decides when an alteration has to meet current code vs. when it stays grandfathered.
Existing-plus-addition (whole-building performance)
An optional whole-building performance path that lets a designer combine an addition and the underlying existing residence in a single compliance model — a rare hybrid used when value-engineering trade-offs flow between addition and existing.
Small-project PV exception
The carve-out from the §150.1(c)14 solar PV mandate for projects where the prescribed PV system is too small to install economically, typically detached ADUs under ~700 ft² in low-PV-factor climate zones.