When is a repair enough?
A repair usually makes sense when the damage is in one place and the rest of the roof is sound: a cracked pipe boot, a few missing shingles after a windstorm, flashing that has pulled away at a wall or chimney, or a single slipped tile. Ask the roofer to photograph the problem and the surrounding roof so you can see the difference.
When does replacement make more sense?
- Shingles are curling, cracking or shedding granules across most slopes.
- Leaks show up in different places each winter.
- The deck feels soft or sags in more than one area.
- The roof is at or past the typical life for its material (see the table below).
- Repairs have been made several times in the last few years.
Can a new roof go over the old one?
Sometimes, but California's Residential Code limits it. Under Section R908, a roof recover isn't permitted where the existing roof is water-soaked or too deteriorated to serve as a base, where it is slate, clay, cement or asbestos-cement tile, or where it already has two or more layers of any roof covering. In those cases everything comes off down to the deck.
How old is too old?
Expected life depends on the material, installation and maintenance. InterNACHI's estimated life expectancy chart gives these guidelines:
| Roofing material | Estimated life (years) |
|---|---|
| Asphalt shingles (3-tab) | 20 |
| Asphalt shingles (architectural) | 30 |
| Wood shakes or shingles | 25 |
| Metal | 40 to 80 |
| Clay or concrete tile | 100+ |
| Slate | 60 to 150 |
| Built-up roofing (flat) | 30 |
| Modified bitumen (flat) | 20 |
| TPO (flat) | 7 to 20 |
| EPDM rubber (flat) | 15 to 25 |
Source: InterNACHI Standard Estimated Life Expectancy Chart. These are guidelines under normal conditions, not guarantees.
What's typical for homes in the South Bay?
Palo Alto's median home dates to 1963, Cupertino's to 1973, and San Jose's and Sunnyvale's to 1976. Those decades produced large tracts of similar homes, including many Eichlers with flat or low-slope roofs, so whole neighborhoods tend to reach replacement age around the same time.
How do insurance and roof age factor in?
Insurers look at roof age and condition when they decide whether to renew a policy. Starting January 1, 2028, California's SB 1301 bars an insurer from refusing or nonrenewing a policy solely because of roof age if you pay for an independent inspection that confirms at least five years of useful life remaining. Read our insurance guide for the details.
Frequently asked questions
How do I know if I need a new roof or just a repair?
A localized problem on a roof with life left is usually a repair. Wear across the whole roof, leaks that keep moving or a soft deck point toward replacement. Ask for photos and a written assessment, and get a second opinion for a big decision.
Can I put a new roof over my old one in California?
Not if the existing roof already has two or more layers, is water-soaked or badly deteriorated, or is slate, clay, cement or asbestos-cement tile, under California Residential Code Section R908.
How long does an asphalt shingle roof last?
InterNACHI's life expectancy chart estimates about 20 years for 3-tab shingles and 30 years for architectural shingles under normal conditions.
Will a repair satisfy my insurer?
It depends on the insurer's concern. If they flagged a specific defect, a documented repair may resolve it. If they flagged age, ask what evidence they accept, and know that SB 1301 adds inspection rights starting in 2028.
Sources
- 2025 California Residential Code, Section R908 (reroofing)
- InterNACHI: estimated life expectancy chart
- SB 1301 (Chapter 693, Statutes of 2026)
- CSLB: check a license
Sources reviewed November 11, 2026. Figures are published estimates and official fees, not quotes. Confirm prices, permits and requirements with your contractor and building department. This page is general information, not legal or insurance advice.