How to Choose the Best Double Glazing Companies Near Me Keep an eye out for accreditations if you're looking to buy double-glazed windows. These include FENSA, a government-authorised scheme that monitors building regulation compliance for replacement windows. The top double-glazing firms include Everest, Anglian Home Improvements, Safestyle UK and CR Smith. They provide a ten-year guarantee on the installation and products and offer interest-free credit options. ...