Most people shop for a roof the same way they shop for a plumber: they call three names, ask what it costs, and go with the middle price. That works fine for a faucet. A roof is a bigger bet, and the mistakes are the kind you don't find out about until the next rainy season, when water is coming through a ceiling that was supposedly just replaced.
Here's what actually separates a contractor worth hiring from one you'll be calling a lawyer about later.
Check the license, not the truck lettering
In California, roofing work requires a C-39 license through the Contractors State License Board. Anyone can look up a license number in about thirty seconds on the CSLB website and see whether it's active, whether there's a bond behind it, and whether there have been disciplinary actions. If a contractor hesitates to give you the number, or gives you a number that comes back to a different company name, stop there. This isn't a formality. The bond and the license are what give you somewhere to go if the work fails.
Ask about workers' compensation coverage too, separately from general liability. Roofing has one of the higher injury rates of any residential trade, and a worker falling off a two-story pitch in Ganesha Hills with no comp coverage becomes your problem, not just his.
What a real bid looks like
A serious bid names the product by manufacturer and line, not just "30-year shingle." It says whether the job is a tear-off or a layover. California building code allows a maximum of two layers of composition shingle before a full tear-off is required, and a lot of the older homes around the Lincoln Park and southwest Pomona neighborhoods, built in the 1940s and 50s, are already sitting on two layers whether the homeowner knows it or not. A contractor who quotes a layover without checking what's already up there is either careless or hoping you won't notice the third layer being illegal.
The bid should also spell out underlayment, whether that's synthetic felt or a self-adhered membrane at the eaves and valleys, and it should list flashing work around chimneys and skylights by name rather than folding it into "miscellaneous." Flashing is where most leaks start, not in the field of the roof itself. If a bid doesn't mention it, ask why.
Get the permit cost and the dump fee written in as separate line items. Pomona's building and safety division requires a permit for roof replacement and inspects at tear-off and at final, checking underlayment and flashing before it's covered up. A contractor who tells you permits are "optional" or "not necessary for a reroof" is either wrong or trying to skip an inspection they don't want a city inspector looking at.
Deposit money is regulated, and that matters here
California law caps the deposit a contractor can collect upfront at 10 percent of the contract price or $1,000, whichever is less. This is not a negotiable industry norm, it's the law. If someone is asking for a third of the job cost before a single shingle is on the truck, that's not standard practice, that's a request to walk away from.
The same goes for full payment demanded before the work is finished. Payment should track the work: a small deposit, progress payment once tear-off and dry-in are done, final payment after the city inspection passes and you've walked the roof or had it walked for you.
Storm chasers and other things to walk away from
Pomona doesn't get hurricanes, but it gets Santa Ana wind events in the fall, sometimes gusting past 60 mph, and those winds lift ridge caps and tear loose tile that wasn't set with enough foam or mortar. After a bad wind week, expect door knockers offering a free inspection and a suspiciously specific list of damage they "found" on your roof. Some of it is real. A lot of it is a sales script. If someone you didn't call is already holding a contract and a pen when they knock, get a second opinion before you sign anything.
Other signs to walk away from: no written contract, a bid with no start or completion date, a company with no local address you can find, or someone who won't do a magnetic sweep of the yard after tear-off to pick up dropped roofing nails. That sweep takes fifteen minutes and it's what keeps a nail out of your dog's paw or your car tire two weeks later.
What the local housing stock changes about the job
Older neighborhoods near downtown Pomona and around Ganesha Park still have a fair number of clay and concrete tile roofs from the original construction. The tile itself often outlasts the house, but the underlayment beneath it doesn't; it's usually rated for 20 to 30 years and gets brittle from the summer heat long before the tile shows any wear. A contractor who just re-lays cracked tile without lifting it to check the felt underneath is patching a symptom, not the problem.
Newer subdivisions out toward Phillips Ranch, built mostly from the 1980s on, are more often composition shingle on standard truss framing, and many of those neighborhoods have an HOA with its own rules about shingle color and material that need sign-off before work starts. Worth asking about upfront so it doesn't hold up a permit later.
Flat and low-slope roofs, common on additions and on some of the ranch-style homes from the 1960s, need a slope of at least a quarter inch per foot to drain properly. Ponding water after a winter storm usually means that slope was never built in correctly, not that the roofing material failed.
None of this is complicated once you know what to ask. A contractor who answers these questions without hesitating has probably done the work enough times to know where it goes wrong. That's the whole test. If you want to talk through a specific roof, Top Notch Roofing Inc can walk it with you and tell you straight what it needs and what it doesn't.