Choosing a covering in Los Angeles means weighing fire class, heat, weight and the cool roof test together, then asking what layers sit beneath it. Shingle, tile, metal and flat membranes each come out differently on those terms.
The parts of the roof, by name
A valley is the V-shaped channel where two slopes meet. A rake is the sloped edge at a gable end, and an eave is the low edge over the gutter line. Flashing is the metal that seals joints at walls, chimneys and openings.
These are the places water collects or changes direction, so they are also where underlayment and flashing earn their keep, whichever covering is on top.
Four families of covering
Asphalt shingles are the lightest of the common coverings and come in several grades. Concrete and clay tile are heavy and long-lived on top, with underlayment beneath that wears faster. Metal comes as panels or standing seam, and some finishes are cool rated. Flat roofs use membranes, and low-slope roofs have their own cool roof targets.
Composite slate and synthetic shake are molded polymer pieces that imitate heavier materials. Fire performance depends on the whole assembly and not on the covering name alone.
How heavy is tile compared with shingle?
Tile is heavier than shingle, and the difference is why framing capacity gets checked before a tile roof is specified. Weight also touches the code. The City's express re-roof items cover Class A or B coverings under 6 pounds per square foot (LADBS, 2026). The state cool roof test leaves out roofs at or above 25 pounds per square foot (California Energy Commission, 2022 Standards).
For a heavier covering, ask the permit office how the job is routed.
Fire, heat and what is restricted
Section 1505.1 of the building code names three classes, and the City of Los Angeles hands them out by map (LADBS, 2026). A Very High zone means Class A only, Fire District No. 1 means A or B, and elsewhere in the City any of the three passes. Within the City, wood shake and wood shingle cannot be installed, though a modification request may allow repairs of up to 5 percent. Reroofing with them is also forbidden in County jurisdiction.
On the heat side, some metal finishes are cool rated, and steep slopes in zones 4 and 8 through 15 can pass with SRI 16. Check the address on the CAL FIRE map viewer.
How long a covering lasts
No single figure fits every roof, because the layers do not wear together. A tile can stay sound while the underlayment beneath it dries and cracks, and a metal panel can outlast its fasteners and flashing.
Insurers add their own clock. Insurance Business America (26 May 2026) names two carriers that decline homes with roofs past 25 years, tile and slate aside. The sensible comparison is the whole stack, not the covering's brochure.
Materials questions, answered
What is a valley on a roof called?
A valley. It is the V-shaped channel where two slopes meet, and it carries water off the roof, so its flashing and underlayment matter more than most.
How heavy is tile compared with shingle?
Tile is heavier. Framing is checked for the load before tile goes on, and weight appears in the code, which sets 6 pounds per square foot for the City's express re-roof items (LADBS, 2026).
What is the most common roof type in California?
Shingle, tile, metal and flat membranes are all installed across the state, and no ranking is offered here. For any one house the question is what its framing, fire zone and cool roof test allow.