Do You Need Gutters in Los Angeles?

• Roof drainage on problem soils. Where expansive or collapsible soils are known to exist, every house needs a controlled way to collect roof water and discharge it at least 5 feet from the foundation walls or into an approved drainage system (CRC 2025, R801.3). The building department or a soils report tells you whether that applies.
• Drainage on every lot. Surface water has to be directed to a storm drain or another approved point, and the ground has to slope away from the foundation, falling at least 6 inches within the first 10 feet; where walls or slopes make that impossible, drains or swales do the job, and paving within 10 feet of the house slopes at least 2 percent away from it (R401.3).
• Fire zones. Where the wildland-urban interface code applies, gutters and downspouts have to be noncombustible, and gutters need an approved way to keep leaves and debris from collecting (CWUIC 2025, 504.4). The code doesn't make you add gutters; it sets rules for the ones you have. More in WUI roofing requirements in California.

Rainfall is NOAA's 1991–2020 monthly normals added up for the year. Runoff is the roof's footprint, measured flat, times the rain: an inch on 1,000 square feet is 83.3 cubic feet, about 623 gallons. A 2,000-square-foot roof Downtown sheds about 17,770 gallons in a normal year. The Department of Energy's Building America Solution Center notes that this volume, if it isn't carried away, can saturate the soil around a house and wick into the foundation, leading to mold and rot. When the rain comes, and what to do before it, is in getting the roof ready for the rainy season.

• The soil is expansive or collapsible, where the code requires controlled drainage anyway.
• The house has a raised foundation or a crawlspace. ENERGY STAR exempts slab-on-grade houses from its gutter requirement; crawlspaces are what the Building America guidance is protecting from saturated soil.
• The eaves are short. Without gutters, EPA's Indoor airPLUS guidance wants a drip line at least 16 inches out from the foundation wall with siding at least 8 inches above the ground, or the foundation wall at least 16 inches above grade, or wall cladding that tolerates regular wetting over a drainage plane at least 16 inches up.
• Water lands where it shouldn't: on an entry, a walkway, a deck or a patio, or on ground that can't be graded away from the house, such as a hillside lot.

• Downspouts out, not down. Building America's guidance is to pipe downspouts to a sloping grade at least 5 feet from the foundation, or to an underground catchment at least 10 feet away that isn't connected to the foundation drain; a rainwater harvesting system or a lined rock bed with a drain are the alternatives.
• Keep them clear. In a fire zone, the gutters need their leaf protection, and the state's draft Zone 0 rules would require roofs and gutters to be kept clear of leaves and needles; see Zone 0 and your roof.
• Mind the metal near the coast. Two shingle makers warn that copper from algae-resistant shingles can corrode aluminum gutters in some coastal and dry areas; see coastal roofing and salt air.

Code sections, rules and figures on this page come from the primary sources below. Codes, local requirements and product terms change; each was verified October 9, 2026.

1. California Residential Code 2025, Chapter 8 Roof-Ceiling Construction, R801.3 (UpCodes)
2. California Residential Code 2025, Chapter 4 Foundations, R401.3 (UpCodes)
3. California Wildland-Urban Interface Code 2025, Chapter 5, 504.4 (UpCodes)
4. U.S. Department of Energy, Building America Solution Center (PNNL), Gutters and Downspouts
5. NOAA NCEI, U.S. Climate Normals 1991–2020, monthly normals for Los Angeles Downtown USC (USW00093134), Burbank (USW00023152), Van Nuys…