Most of the trim on a standing seam roof comes down to six shapes: eave, rake, ridge and hip cap, sidewall, headwall, and valley. Know what each one does and which dimension drives it, and you can call in a trim order in a few minutes instead of a few phone calls.
The six shapes
Eave trim (drip edge) and gutter apron
Eave trim runs along the low edge of the roof. It carries water off the panel and past the fascia board. On standing seam the panel's bottom edge is hemmed and hooks onto the hemmed drip leg of the trim, or onto an offset cleat, so it also holds the panel down at the eave.
Gutter apron is the same piece with a longer face that drops behind the back of the gutter, so runoff lands in the gutter and not behind it. The dimension that matters on both is the face, or fascia drop.
Rake (gable) trim
Rake trim covers the panel edge running up the gable. It keeps wind-driven rain from getting under the last panel. It hooks over a Z-closure or a turned-up panel edge, and the face drops down the rake board. Two dimensions drive it: seam height, because the top of the trim has to clear the rib, and fascia drop on the gable side.
Ridge cap and hip cap
Same profile, different job. Ridge cap covers the peak. Hip cap does the same on a hip. Under both is a Z-closure set in butyl tape across the panel flats, cut to fit between the seams. The cap hems over the Z or fastens to it. On a hip the panels are cut on an angle, so each Z is cut at the hip angle and fitted between seams. What matters is seam height, so the legs clear the rib, and roof pitch, so the bend at the peak sits flat.
Sidewall flashing
Sidewall is where the roof runs alongside a wall. One leg goes up the wall behind the weather barrier and siding. The other comes out over the panel edge and hems over a Z-closure or the turned-up edge of the last panel. Seam height sets the step in the flashing. For the up-wall leg, most manufacturer details want at least 4 inches up the wall and some want more, so check yours.
Headwall (endwall) flashing
Headwall is where the roof slopes into a wall and the panels stop. The panel ends get a Z-closure set in butyl. The flashing runs up the wall behind the siding, comes down over the Z, and ends in a hemmed drip onto the panel. Two legs matter: the up-wall leg, and the roof-side leg, which has to reach past the Z and clear the ribs.
Valley
A valley is where two slopes drain into each other. For standing seam the standard is a W-valley. The center rib keeps water coming down one slope from shooting across and under the panels on the other. The edges are hemmed or fitted with an offset cleat so the panels, cut on the angle and hemmed, hook in without face fasteners. Butyl tape or foam closure goes along the valley flange under the panel ends. Width is the number here, and the hem has to match the panel hem.
The pieces that make the six work
- Z-closure (Z-bar). A Z-shaped bar matched to the seam height, set in butyl tape on the panel flat and fastened through to the deck. Ridge, hip, headwall, rake, and pitch break trims all hook to a Z. It seals the open end of the panel and gives the trim something solid to fasten to. It is cut to fit between seams.
- F-channel. An F-shaped receiver. Used at the soffit to hold soffit panels, and under rakes and wall trims where the trim slides into a channel instead of taking face fasteners.
- Kickout. Not a separate profile. It is the bottom piece of sidewall flashing, or a short piece in the same profile, bent to turn water out into the gutter instead of behind the siding. The IRC (R903.2.1) requires a diverter where an eave meets a sidewall. Order it left or right, in the sidewall profile.
- Pitch break (transition). Where the roof slope changes. The lower panels end with a Z-closure, and the transition flashing tucks under the upper panels and laps down over the Z, ending in a hemmed drip. It is bent to the actual change in angle, so give both pitches.
Which dimension actually matters
| Trim | Dimension that drives it |
|---|---|
| Eave / drip edge | Fascia drop |
| Gutter apron | Face (fascia drop) |
| Rake | Seam height, fascia drop |
| Ridge / hip cap | Seam height, pitch |
| Sidewall | Seam height, up-wall leg |
| Headwall | Up-wall leg, roof-side leg |
| Valley | Width, hem size |
| Z-closure | Seam height, panel coverage |
| Pitch break | Both pitches |
Seam height shows up most. Common standing seam profiles run 1, 1-1/2, 1-3/4, and 2 inches, and any trim that crosses or sits beside a seam has to be made for that height. Gauge and color match the panel, usually 24 or 26 gauge. Trim is normally made in 10-foot sticks, so count your laps when you figure lengths.
Hems
A hem is the edge folded back on itself, and it does two things. It stiffens and cleans up the edge: a raw edge on light-gauge steel waves and shows the cut. And it is a connection. A closed hem, folded flat, is the edge the next piece hooks onto, like the drip leg on eave trim or the lip of a cleat. An open hem, folded with a gap left in it, is the one that slides over a closed hem. The panel's eave hem is left open for that reason. A 1/2-inch hem is typical on exposed edges. When you order, say which edges are hemmed and whether they are open or closed.
Frequently asked
What is the difference between drip edge and gutter apron?
Both sit at the eave and carry water off the panel, but gutter apron has a longer face that drops behind the back of the gutter so runoff cannot get behind it. Use apron where there is a gutter and drip edge where there is not.
Which dimension matters most when ordering standing seam trim?
Seam height. Any trim that crosses or sits beside a seam, including ridge, hip, rake, sidewall, headwall, and Z-closures, has to be made for the panel's seam height, which commonly runs 1, 1-1/2, 1-3/4, or 2 inches.
What does a Z-closure do on a standing seam roof?
A Z-closure is a Z-shaped bar matched to the seam height, set in butyl tape on the panel flat and fastened to the deck. It seals the open end of the panel and gives ridge, hip, headwall, rake, and pitch break trims something solid to hook to.