Guide · Roofing and solar
If the roof has fewer good years left than the panels, replace it first. A solar array is a 25-year asset bolted to whatever is under it, and removing and reinstalling it later to reroof is labor you pay for twice. In the San Gabriel Valley that question comes up constantly, because much of the housing dates from the 1950s and 1960s and a reroof in 2026 has to meet new cool-roof and, in the foothills, Class A fire rules.
Facts checked September 21, 2026
Panels last about 25 years. If the roof under them will not, the roof goes first. That is the whole rule, and it is the one a solar salesperson has the least incentive to bring up, because checking the roof risks losing the sale.
The reason is cost, not warranty. Nothing about putting solar on an old roof voids the panels, and nothing about a later reroof voids them either. What it does is force a second job: the array comes down, the roof is torn off and rebuilt, the array goes back up with every mount reflashed. Los Angeles County's reroofing code manual describes that exact sequence for homes with an existing system, and it is real labor, twice, with a leak risk in between and two companies to argue about whose fault it was.
| Roof type | What wears out | Signs it is near the end |
|---|---|---|
| Composition shingle | The shingle itself. Architectural shingles from GAF or Owens Corning are rated for decades, but a 1990s three-tab roof is not. | Granules in the gutters, curling or cupped edges, bald patches, more than one layer, or a roof that was already patched. |
| Concrete or clay tile | The underlayment beneath the tile, not the tile. Tile can last 50 years; the original felt under it usually cannot. | Brittle or cracked felt when a few tiles are lifted, slipped tiles, stains on the underside of the deck, or original underlayment on a 1970s or 1980s house. |
The count-the-layers test matters here more than in most places. The median home in West Covina was built in 1967, in Covina 1965, in Pomona 1967, and in Glendora 1964, and in each of those cities a third or more of the housing went up in the 1950s. A 1950s ranch house has had time for three shingle roofs, and a lot of them got the second and third as overlays on top of the first. Two or three layers of shingle add weight, hide rotten decking, and cannot take a solar mount reliably. A house like that needs a tear-off, not another layer.
Two sets of rules changed or tightened recently, and both affect what goes on the roof.
The 2025 California Energy Code took effect for permits applied for on or after January 1, 2026. For a steep-slope reroof on a single-family home in Climate Zone 9, which covers the San Gabriel Valley, the roofing product must have an aged solar reflectance of at least 0.20 and a thermal emittance of at least 0.75, or a solar reflectance index of at least 16. The values are unchanged from the 2022 code, but the cycle is new and cities such as San Dimas now accept only plans drawn to the 2025 codes.
The exceptions, any one of which lets a non-cool product be used:
In practice this is not a hardship. GAF and Owens Corning both make cool-rated colors in their architectural lines, and most homeowners never notice the difference except on the summer power bill.
CAL FIRE released new Fire Hazard Severity Zone maps for Los Angeles County in March 2025, and the Very High zones grew: more than a third of La Verne, about a third of Diamond Bar, all of Glendora north of Sierra Madre Avenue plus its South Hills, and pockets in Walnut, San Dimas, Azusa, and West Covina. Inside those zones a reroof is a different job:
Both GAF and Owens Corning architectural shingle systems and concrete tile are Class A when installed as a full system, so the material choice rarely changes. What changes is that the overlay shortcut is off the table and the eave and vent details are inspected.
The order is fixed: the array bolts into the roof structure, so the roof is finished before racking goes on. The question is whether the two jobs run as one project or as two contracts a year apart. One project means one assessment, one permit package, one mobilization, mounts flashed into the new roof rather than cut into a finished one, and one company responsible for the whole assembly if a leak shows up under the array in year six. VertX prices the roof and the system together and puts the combined number in writing; the roof and solar bundle page explains how that works, and the roofing page covers materials.
And if the inspection says the roof is fine, the answer is fine. Solar goes on it as it is, with the flashing details done right, and the roof question is closed for good.
Common questions
For composition shingle, count the layers and look at the granules. A roof on its second or third layer, or one shedding granules into the gutters with curling or bald spots, is at the end of its life regardless of age. For tile, the tile itself is rarely the problem; lift a few tiles on the sunniest slope and check whether the underlayment is still pliable or has gone brittle. A roof inspection with photos, which we do free, settles it in an hour.
The panels will outlast the roof, and when the roof fails someone has to remove the array, reroof, and reinstall it. LA County's reroofing code manual spells out that sequence for homes with existing panels: the system comes off, the roof is redone to current code, and the system goes back with the mounts reflashed. That round trip is labor you pay for twice, plus a leak risk in the meantime, plus a warranty argument between two companies.
Usually. Under the 2025 California Energy Code, in effect for permits from January 1, 2026, a steep-slope reroof on a single-family home in Climate Zone 9 must use a roofing product with an aged solar reflectance of at least 0.20 and a thermal emittance of at least 0.75, or a solar reflectance index of 16. There are exceptions, including R-38 attic insulation, a radiant barrier, no ducts in the attic, or a heavy roof assembly of 25 pounds per square foot or more. GAF and Owens Corning both make shingle colors that meet the requirement.
The roof assembly has to be Class A. In Los Angeles County jurisdiction, any new roof or any reroof covering more than half the roof area in a year inside a Fire Hazard Severity Zone must be Class A, and state Chapter 7A construction standards apply in the Very High zones. The county manual also bars laying new shingles over old ones in Very High zones. Cities such as Glendora, La Verne, and Diamond Bar adopt their own versions, so we check the parcel on the city map before quoting.
Almost always, compared with doing them a year or two apart. One permit package instead of two, one crew mobilization, mounts flashed into the roof as it is built instead of cut into a finished one, and one warranty covering the whole assembly. We price the two as one project and put the combined number in writing.
