Lifetime Windows & Siding has over 15 years of combined experience selling and installing replacement windows in Denver. We are the #1 Infinity from Marvin fiberglass window dealer in the country and we offer a lifetime warranty on all labor and materials. The windows we use are not only attractive, but durable, energy-efficient and backed by ENERGY STAR®. We have over 10,000 happy customers and look forward to working with you!