Is Flashing Needed for a Window Install?

Flashing Basics

• Flashing comes in many forms, ranging from metal strips to pieces of plastic and modified polymers. For windows, it most often takes the shape of an L, with the flashing installed in such a manner that the piece wraps the seam around the entire window frame. This protects the seam around the window frame. Once it is installed, the wrapped piece of flashing works with the other waterproofing elements that are part of the siding installation to keep water from sinking in.

Installation

• The types of materials you can choose from when it comes to window flashing is varied. Copper and metal flashing are common choices, but you can also find special membrane flashings with tar-based adhesives that can be put on like a bandage, covering the seams. Regardless of which method you choose, it is important to follow the window manufacturer’s recommendations for type of flashing so that your warranty is covered.

Materials

• You should always use the proper installation materials for the flashing protocol your window manufacturer recommends. For example, metal flashing is generally installed with some type of caulking adhesive, with silicone being the most common choice. However, there are also polyurethane adhesives and tar-based adhesives. Always use the recommended type so you can ensure the longevity of the installation and proper water protection.

Siding

• The waterproofing for the siding is also an important part of the window installation, as the flashing ties into the waterproofing for the siding. For example, a copper flashing is installed in such a way that it overlaps the waterproofing protocol for the siding, and the siding itself is installed on top of the flashing. The siding works as the primary waterproofing for rain and the elements, while the flashing and moisture barrier beneath the siding help keep any residual water, such as from condensation, from penetrating through the wall.