San Diego attics need R-30 to R-38 in new homes and R-49 when an inland, mountain or desert attic is altered, depending on climate zone 7, 10, 14 or 15. Coastal zone 7 upgrades only require R-19, but ENERGY STAR recommends R-38 to R-49.
For most San Diego attics, blown-in cellulose or loose-fill fiberglass to R-38 to R-49, with air sealing first, is the best value. Spray foam wins when ducts run through the attic, the roofline is complex, or air leakage is severe.
Six San Diego attic cleaning and insulation providers, compared on scope, coverage, inspection process and fit. We publish this guide and we rank ourselves first, for the reason below. Check every provider's license and written scope before you book.
The most effective way to lower a San Diego energy bill in 2026 is to fix the building envelope first (Title 24-compliant windows, attic insulation, duct sealing), replace an aging air conditioner with a SEER2 heat pump, then shift remaining usage away from SDG&E's 4-9 p.m. peak using a smart thermostat, shading, and appliance timing.
For San Diego homes in 2026, casement and fixed picture windows rank as the most energy-efficient types, followed by sliding and double-hung, because their tighter seals and compression locks meet Title 24's 0.30 U-factor and 0.23 SHGC thresholds most easily with standard Low-E dual-pane glass. No triple-pane upgrade is required for code compliance.
