To hire a reliable commercial glass & curtain wall installation contractor in Philadelphia: (1) Get 3 written quotes with line-item breakdowns, (2) Verify PA license at Pennsylvania Attorney General Home Improvement (attorneygeneral.gov), (3) Confirm active general liability and workers' comp insurance, (4) Check Google and BBB reviews specific to Philadelphia projects, (5) Never pay more than 10-30% upfront — never pay in full before completion.
Full Explanation
Red flags specific to Philadelphia contractors: no physical Philadelphia-area address, pressure to start immediately, cash-only payment demands, and license numbers that don't verify at Pennsylvania Attorney General Home Improvement (attorneygeneral.gov). Seasonal demand during summer brings out less reputable contractors.