Vinyl siding: Windows must be properly trimmed during installation

Vinyl siding: Windows must be properly trimmed during installation

Vinyl siding is affordable, good-looking and easy to maintain, and it protects homes against all kinds of weather. But, to be effective, vinyl siding must be installed properly. Otherwise it might leak, allowing water to enter along panel edges or where panels meet windows or doors.

Contractor or DIY?

Some homeowners are handy enough to install new siding by themselves, but most seek multiple estimates from installers or contractors. These preliminary conversations should not only cover the style, color and cost of siding panels, but also deal with trim pieces and where they will be installed.

Installers also devote a lot of time and attention to details like window trim, flashing, sealants and insulation because they know that a little extra time up front can pay dividends in homeowner savings in the long run. For instance, before you even start the application of vinyl siding, windows might require flashing and caulking as an extra layer of weather protection.

Vinyl siding key terms

As a homeowner, whether you "do-it-yourself" or hire an installer, you will want to familiarize yourself with some key terms relating to vinyl siding installation around windows:

  1. J-channel is a narrow piece of vinyl trim that literally looks like a J from the side. It is designed to fit snugly around window frames to receive the ends of siding panels. J-channel plays both practical and decorative roles in installation of vinyl siding: Windows and siding are sealed against water seepage while edges of siding panels are neatly hidden.
  2. Under sill, or utility trim, is used when the top nailing strip of a siding panel has been removed because the panel has been cut to fit under a window. The trim piece is installed under the windowsill to receive and secure the cut end of the panel.

When checking either your own work or a contractor's, make sure that the J-channel fits snugly to the window; it might be seated in a bed of caulking to ensure a watertight seal. Strips at the top and bottom of the window should be miter cut at a 45-degree angle, and fitted carefully into the sidepieces so that the corner is sealed and water is directed around the window frame.





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