Should the Top Flange Be Nailed When Installing Vinyl Windows?

Flange Basics

• Flanges are pieces of material that cover up an existing area. With windows, in particular, they are a combination of waterproofing and mounting mechanisms, depending on the manufacturer. Flanges are designed to be set on top of the wall surface of the home, under the flashing, the waterproofing and the siding of the home. Flanges can be nailed or screwed onto the home's surface.

Window Flashing

• Because all window flanges are nailed or screwed onto the wall surface of the home, they penetrate the wall and thus create leak points where water can penetrate. The flashing for windows is designed to cover this flange and works with the waterproofing element for the siding, as well as the siding itself, to keep any water from eventually getting to the flange and the penetrated sections.

Manufacturer's Guidelines

• When you are deciding whether or not to nail the top flange in a vinyl window installation, there is one rule that trumps all others: follow the manufacturer’s guidelines for installation. If you make any variations on the manufacturer's recommendations in terms of spacing the nails and screws, you void any warranty the manufacturer provides for that window. If anything fails down the road, it will be on you, not the manufacturer, to fix it.

Screws Versus Nails

• The biggest decision, when mounting a window flange to the wall, is whether to use screws or nails. While you should always follow the manufacturer's guidelines for spacing -- most flanges have pre-drilled holes for the nails or screws -- you generally have a choice between the two. Nails are always the fastest method, but they are also difficult to remove should you ever need to replace the window. Screws, on the other hand, can be easily removed should you need to make any repairs.