Vinyl and Metal Siding and Soffit Trim

F Channel. J Channel. Starter Strip. Z Metal. Drip Edge. T Channel. Utility Trim.

There are a confusing amount of flashing and trim options available for Metal Siding and Vinyl Siding.  The question becomes which to use, where to use it and what options are available.

Vinyl Siding comes with a top lock to snap the panels together.  When you trim a panel for a window, though, the top lock may get removed from a section.  This is where Utility Trim comes to use – it fits below the window and replaces the top lock, keeping the siding to a snug fit.  This does not replace the J channel used around the window (or door) to keep water out. 

Vinyl Soffits are installed using a combination of flashing and channels depending on the type of soffit being installed and taking into account new construction vs. re-siding an older home.  There are a plethora of choices as to which channel set up to use depending on nailing preference, soffit style and available nailing surfaces.  The F and J channels are common – but in some areas where a back-to back J would be needed, a T can be used for a cleaner look.

Metal Siding uses J Channel and F trim, but also has door trim, Jamb trim, Liner trim, Corner trim, Inside Corner trim, flashings and eave trims in an amazing array of types and styles.

All of these general flashing types are in addition to any manufacturer specific requirements that may be required for warranty validation.  Manufacturer’s specifications are the key in order to be sure there is an approved material used.

There is no way to cover all of the possibilities with flashing here – but some broad guidelines can help. When we are talking water, it needs to be noted that at any seam, joint, corner, transition or any other connection where water can find a wick point, flashing can be used to redirect the water away from the building cavity.  Using manufacturer specifications for installing siding, roofing, trim, windows, doors and other water sensitive areas is probably the best practice – but make sure that you take your location into consideration.

The Vinyl Siding Institute has an installation guide that can give you more information.  Check it out at

Metal siding is a bit more challenging to run down since the type and style of panels will dictate the flashing used and installation method.  For more information, search for specific manufacturer or panel type flashing and installation.

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