Let’s Pick a Name

Jim Snyder
March 24, 2015
THE TALK... | Materials & Components

One window design trend in recent years is a movement toward a “narrow, flat, pre-punched appendage around the entire perimeter through which we drive nails to anchor the fenestration to the wall structure.” 

You may be wondering why I’m being so abstract in terming this component. I choose to because there is no one term and I want you to consider what you would naturally call it. May I add that I am not referring to that “narrow, sometimes wide, exterior-most, flat perimeter appendage that has more to do with exterior sealing and trim-out than with structural anchorage.”

I talk about both however, in this month’s From the Field column, because there is surprisingly frequent confusion in the differences. #applesandoranges

The industry as a whole has difficulty pinning down an all-inclusive term for this anchoring appendage. While participating in industry document creations and revisions, our task groups often pause on which term best captures this element. I think that’s maybe how “appendage” was introduced.

Although this component has been around, to my knowledge, since the introduction of aluminum residential windows in the 1930s, its use is growing as new generation extruded/pultruded frame materials and clad-wood products have been introduced in the past few decades. Even some all-wood products are starting to use this component in a revolutionary way.

This prompted my question in this week’s poll, because I’ve heard all of these terms used. Please reviewthe poll, leave a comment or email me if I’ve missed one.

Survey Results for 03/25/2015 :

What is your default terminology for this anchoring appendage?

Nail fin





Mounting flange





Mounting fin





Installation fin





Installation flange





Fin (window)






Jim Snyder is an AAMA-certified FenestrationMaster and InstallationMaster who shares his years of installation field experience as an industry writer, speaker, trainer and project/product consultant for dealers and manufacturers. A member of various industry organizations, Snyder also is involved in instructional document creation and revision. Contact him at jim@windowjim.com.