Focus on French Doors

Sun, wind, rain, snow — it just doesn’t matter. Because a French door gets installed where the view is, regardless of weather conditions. Fortunately, manufacturers have spent the 50 or so years that pre-assembled patio doors have been on the market figuring out how to build some pretty airtight units.

In fact, if a patio door from one of the major door and window companies leaks at all, chances are that the fault lies with the installation — not the door. Gene Summy of TLS Laboratories, a window and door testing company in Laguna Niguel, Calif., says the single biggest factor in door performance is how well it was installed. “Most...