Skylight Replacement — Title 24 + LA Permit Guide (2026)

CEC 2025 Title 24 Part 6 §150.2(a), effective January 1, 2026 as the current code cycle, requires every replaced skylight in existing residential construction to meet a maximum U-factor of 0.55 (lower is better) and a maximum SHGC of 0.30 (lower is better). These are the prescriptive default values — a performance approach via ResCheck or HERS can substitute compliance across the whole envelope, but the prescriptive numbers are what LADBS plan-check uses for single skylight swaps.

Pre-2005 acrylic bubble skylights typically rate at U-factor 1.05 to 1.25 and SHGC 0.65 to 0.78. That is roughly double the current U-factor limit and more than double the SHGC limit. A like-for-like acrylic bubble replacement FAILS §150.2(a) every time and will not pass plan-check.

Modern double-glazed argon-filled flat-glass skylights from Velux, Fakro, or Solatube hit U-factor 0.35 to 0.48 and SHGC 0.22 to 0.28 when specified with low-E coating and argon fill. The NFRC label on the skylight unit is the document LADBS inspectors verify on site.

Single-glazed polycarbonate or acrylic replacements (common in garages, sheds, and accessory structures exempt from Title 24) are still manufactured and sold — they are legal for non-conditioned spaces only. Interior-conditioned residential space replacement must be dual-glazed with a rated NFRC label.

California Building Code §2405.5 requires skylight glazing to be one of: fully tempered glass, heat-strengthened glass, wired glass, laminated glass, or approved plastic. The glazing location (slope, height above floor, occupiable space below) determines which of these is acceptable.

Residential bedroom and living-area skylights with walkable floor beneath them must use laminated glass or an approved screen below the skylight to catch breakage. §2405.5 exception 2 allows tempered upper-lite if a lower laminated glass lite is installed below it (the common double-lite assembly in manufactured units from Velux and Fakro).

Acrylic plastic skylights are still allowed under §2405.2 for buildings Group R-3 (single-family residential) when the acrylic meets CC1 or CC2 classification for light transmission and smoke development. The acrylic bubble skylight market has shrunk to mostly accessory-building and commercial flat-roof applications in 2026.

Safety-glazing labeling is printed on one corner of the glass and must remain readable after installation. LADBS inspectors check for the etched ANSI Z97.1 or CPSC 16 CFR 1201 label at final inspection. An unlabeled glazing panel is treated as non-compliant regardless of actual material.

LADBS Information Bulletin P/BC 2020-079 references CRC §R308.6.8 and Manufacturer's Installation Instructions (MII) for curb-mounted skylights. The curb must be framed with minimum 2x4 lumber on edge (3.5 inches tall), flashed with step flashing and counter-flashing integrated into the roof underlayment.

The skylight curb must rise a minimum of 4 inches above the finished roof surface on the uphill side (so water flowing down the roof does not enter the skylight perimeter). Velux and Fakro sell prefabricated metal flashing kits that meet this 4-inch requirement; site-built flashing can be used but must be documented on the plans and photographed during inspection.

Deck-mounted (frameless, curb-less) skylights are only allowed on low-slope roofs (2:12 or less) per most manufacturer MIIs. LA residential roofs are typically 4:12 to 6:12 pitch — putting almost every house firmly in curb-mount territory.

Flashing failures are the #1 cause of post-install skylight leaks in LA. The Santa Ana wind events in late-year drive rain horizontally under insufficient counter-flashing, even on otherwise-compliant installs. Budget for a licensed roofer to integrate the curb flashing with the surrounding underlayment rather than relying on caulking alone — caulked skylight installs have a 3 to 5 year service life; properly-flashed installs run 20+ years.

Like-for-like skylight replacement where the rough opening is not changed: the permit is available via PermitLA Express online submittal, typically approved within 24 hours. The fee is in the $180-$320 range depending on the skylight cost, plus a $65 inspection fee.

New skylight opening (cutting a new rough opening in the roof, which requires rafter modification or header installation): the permit requires full plan-check, typically 2 to 4 weeks at LADBS Metro or Van Nuys. Fees run $420 to $780. Structural plans stamped by a California-licensed engineer are required if any rafter is cut or tied into a header.

Powered (operable) skylights with motorized opening or integrated powered shades require an additional electrical permit. LADBS treats the motor as a branch circuit extension; the permit can be added to an existing electrical permit or filed as a separate Express electrical permit. 2026 fee: $140 to $210 for the electrical-only portion.

Final inspection checklist includes: NFRC label photo, flashing integration review (counter-flashing on all four sides), interior drywall fit and seal, and for powered units, GFCI protection on the branch circuit and proper box grounding per NEC §250.

Velux VSE and Fakro FTU operable skylights with factory-integrated motors and shades require line-voltage 120V branch circuits per NEC §210.8 and manufacturer installation instructions. The motor is typically rated 2 to 3 amps, but code treats it as a fixed-in-place appliance requiring dedicated box and strain-relief.

GFCI protection is required per NEC §210.8(E) for receptacles located in unfinished portions of basements, garages, and — per the 2020 and 2026 update — any receptacle within 6 feet of a sink or water source. Roof-cavity motor installations are NOT required to be GFCI by default, but LADBS inspectors increasingly specify GFCI when the motor is accessible from an attic walkway.

Solar-powered skylights (Velux VSS, which use a small integrated PV panel to power the motor and batteries for the shade) do NOT require an electrical permit because there is no building-side branch circuit. These are popular for retrofits in older homes where running a new circuit to the roof cavity is cost-prohibitive; typical installed cost is $2,400 to $3,800 including flashing.

Low-voltage remote-control wiring (24V DC) for dimmer and shade operation is exempt from NEC §210 under the Class 2 circuits exemption in §725 but must still be secured and protected from physical damage. LADBS inspectors will flag exposed Class 2 wiring run across attic spaces without stapling.

Traditional design guidance from the Illuminating Engineering Society (IES) suggests skylight area of 5 percent of the room floor area for supplemental daylight, and 15 percent for primary daylight dependence. LA homeowners often ask for larger skylights thinking 'more light is better,' but the SHGC 0.30 Title 24 limit caps the solar heat gain, and an oversized skylight in a south-facing kitchen hits the HVAC system for 2,000 to 4,000 BTU of additional cooling load on a summer afternoon.

A 4x4 skylight (16 square feet of glazing) in a 200 square foot kitchen is 8 percent of floor area and sits well above daylight minimums. Anything above 15 percent starts to be glare-controlled by blinds most of the day, which defeats the daylight purpose.

Tubular daylighting devices (TDDs) like Solatube are an alternative for spaces where a full skylight is impractical — hallways, closets, powder rooms. TDDs count as skylights under Title 24 and the NFRC rating is pinned to the dome and diffuser assembly. Solatube 290 DS rates at U-factor 0.36 and SHGC 0.20, well under the prescriptive limits.

The 2026 average LA kitchen skylight install cost is $2,800 to $6,200 for a standard deck-mounted dual-glazed unit, $4,800 to $9,500 for a motorized unit with integrated shade, and $2,200 to $3,600 for a TDD.

CBC Chapter 7A Wildland-Urban Interface (WUI) zones apply to skylights in fire-hazard-severity zones throughout LA — the Hollywood Hills, Bel Air, Mandeville Canyon, Pacific Palisades, Topanga, and all non-coastal hillside neighborhoods. §707A.5 requires WUI skylights to be tempered glass or equivalent impact-rated glazing.

The Cal Fire PRC §4291 defensible-space overlay does not directly regulate skylights but does require the 100-foot vegetation-clearance zone around structures, which prevents installing skylights oriented toward overhanging trees that would create ember-ignition paths on the glazing. Specific guidance appears in the roof-replacement CBC Chapter 7A WUI guide at https://askbaily.com/guides/roof-replacement-cbc-chapter-7a-wui.

HPOZ (Historic Preservation Overlay Zone) properties — Larchmont Bungalow, Carthay Circle, Hancock Park, Windsor Square, Whitley Heights, and 30-plus other LA HPOZs — require a Certificate of Appropriateness (COA) from the Los Angeles Office of Historic Resources for any roof-visible skylight installation. Street-visible skylights are typically denied on primary historic facades; rear-roof skylights are usually approved with 8 to 12 week COA review.

Coastal Commission zones (Venice, Malibu, Pacific Palisades coastal overlay, Playa Del Rey) require a Coastal Development Permit or an exemption letter for any new roof penetration, including skylights. Like-for-like replacement in the same rough opening is typically exemption-eligible; a new opening requires the full CDP process.

If your existing skylight is an acrylic or polycarbonate bubble from before 2005, assume full replacement not repair. The U-factor and SHGC non-compliance is immediate; the acrylic UV degradation after 20 years of LA sun makes in-place refinishing impractical.

If the existing skylight is a pre-2015 double-glazed flat unit with minor seal failure (condensation between the panes), a direct Velux or Fakro replacement in the same curb is typically the cheapest compliant path. 2026 unit cost $1,200 to $2,400 plus $800 to $1,600 install for a ~3 to 5 hour project.

If the existing skylight leaks at the curb (water stains on the interior sheetrock, visible drip-paths), assume flashing remediation plus replacement. Budget $3,400 to $5,800 for a full tear-out including counter-flashing integration and interior sheetrock repair.

For homeowners considering a larger fenestration change alongside a skylight replacement — adding windows, upgrading sliders, replacing multiple skylights — see the full window-and-door replacement service page at https://askbaily.com/window-door-replacement-los-angeles.