Direct Answer
To hire a reliable commercial glass & curtain wall installation contractor in Nashua: (1) Get 3 written quotes with line-item breakdowns, (2) Verify NH license at New Hampshire Office of Professional Licensure (oplc.nh.gov), (3) Confirm active general liability and workers' comp insurance, (4) Check Google and BBB reviews specific to Nashua projects, (5) Never pay more than 10-30% upfront — never pay in full before completion.
Full Explanation
Red flags specific to Nashua contractors: no physical Nashua-area address, pressure to start immediately, cash-only payment demands, and license numbers that don't verify at New Hampshire Office of Professional Licensure (oplc.nh.gov). Seasonal demand during summer brings out less reputable contractors.
Local Factors in Nashua
📍Verify license: New Hampshire Office of Professional Licensure (oplc.nh.gov)
📍File complaints: New Hampshire Office of Professional Licensure (oplc.nh.gov)
📍Homeowner protections under NH consumer protection law
📍BBB Greater Nashua chapter for complaints history