Roof Trim · Metal building trim guide
High Side Eave Trim for Single-Slope Metal Roofs
High-side eave trim caps the top edge of a single-slope roof, sealing the panel ends where the roof is tallest.
Also called: peak box, high side trim, peak trim, high eave trim, shed roof peak trim
High side eave trim is the trim that caps the top edge of a single-slope roof, the tall side of a lean-to, shed roof or single-slope carport. It covers the open top ends of the roof panels and the high eave framing so water, wind, birds and wasps stay out.
Single-slope roofs are popular around Houston for carports, equipment covers and add-ons. This guide shows what the trim does, what to order, how to count pieces with a real example, and how to install it so it stays tight in a Gulf Coast storm.
What Is High Side Eave Trim?
On a single-slope roof the panels run from the low eave up to the high side, where they simply stop. High side eave trim, also called a peak box, high side trim or peak trim, closes that edge. It has a top leg that lies on the panels, bent to match the roof pitch, and a face that comes down over the high eave strut or purlin, often with a drip at the bottom.
It does the same jobs a ridge cap does on a gable roof: keep water out of the panel ends, stop wind-driven rain, block birds and bugs, and give a sharp finished line along the tallest edge of the building.
Where High Side Trim Goes on a Metal Building
It goes along the full length of the high edge of any single-slope roof that stands on its own: a single-slope carport, a free-standing shed roof, or the tall side of a lean-to built on its own posts.
If the high side of your lean-to butts up against a taller building wall, you need roof-to-wall flashing there instead, because the trim must seal against the wall. The low edge of the same roof gets regular eave trim or a gutter, and the two sloped sides get rake trim.
Peak Box Trim Sizes, Gauge, Profile and Colors
This trim is typically 26 gauge to match R-panel or PBR, with 29 gauge available for lighter roofs. You can get it in Galvalume or a painted color to match your other trim.
Two things set the shape. First, the roof pitch, because the top leg is bent to the slope of the panels. Second, the depth of the high eave member, because the face has to cover it. Bring both numbers when you order. Pieces are typically 10 ft long; ask us. Custom bends are common on this piece because buildings vary.
How to Measure High Side Trim and How Many Pieces to Order
Formula: length of the high edge (building length plus any overhang on each end) x 1.10, divided by piece length, rounded UP.
Worked example: a 20 x 24 single-slope lean-to with a 2:12 pitch, panels running the 20 ft direction from low side to high side. The high edge is 24 ft. 24 x 1.10 = 26.4 ft, so order 3 pieces of 10 ft high-side trim. Check the run: two full pieces cover about 19.75 ft after the lap, and the third piece finishes the last 4.25 ft or so.
Closures: 24 ft / 3 ft panel coverage = 8 outside closures, plus one or two spares. The two rake edges are each 20 ft x 1.01 = about 20.2 ft, so plan on 5 pieces of rake trim for both sides: two full pieces per side, plus one piece cut in half to finish both runs.
How to Install High Side Eave Trim
Install it after the roof panels are on and fastened, and before or along with the rake trim, depending on how your rake ends are finished.
- Make sure the panel ends line up straight along the high edge.
- Lay butyl tape across the panel flats near the top end, press the outside foam closures into the ribs, and add a second strip of tape on top of the closures.
- Start at the end away from the prevailing wind. Set the trim so the face lines up with the high eave member and the top leg lies on the closures.
- Fasten the top leg through the closure into each major rib with #14 x 7/8 in. lap screws, and fasten the face into the eave member about every 12 to 24 inches with #12 or #14 self-drilling screws.
- Lap each next piece 2 to 4 inches with sealant in the joint, laps facing away from the wind.
- Finish the ends where they meet the rake trim, folding or notching so the rake laps neatly and no open gap is left.
Common High Side Trim Mistakes to Avoid
- Ordering without the roof pitch, so the top leg does not lie flat on the panels.
- Using this trim where the roof meets a wall; that spot needs roof-to-wall flashing.
- Skipping outside closures, which lets wind push rain up the ribs and under the trim.
- Leaving the ends open where the high side meets the rake.
- Measuring the building only and forgetting the overhangs.
What to Order With High Side Trim
A single-slope roof needs a full set of edge trim. Order these together:
- Outside foam closures for under the high side trim.
- Eave trim or gutter for the low edge, with inside closures.
- Rake trim for both sloped sides.
- Butyl tape, color-matched lap screws and roofing screws.
- Touch-up paint in your trim color.
Get High Side Eave Trim in Houston From Ironrod Steel
Ironrod Steel Co. rolls its own R-panel and PBR roofing and supplies matching high side trim, rake, eave trim, closures and screws for lean-tos, carports and shed roofs. Send us the size, roof pitch and a photo of the high eave and we will build your trim list. Pick up at 8122 Hillsboro St in Houston or ask about delivery across Houston and Southeast Texas. Call or text (281) 902-7619.
High-Side Eave Trim FAQ
What trim goes on the high side of a lean-to roof?
If the high side stands free, use high side eave trim (a peak box) with outside closures under it. If the high side touches a building wall, use roof-to-wall flashing instead so it seals against the wall.
Is a peak box the same as high side trim?
Yes. Peak box, high side trim, peak trim and high side eave trim are names for the same piece on a single-slope roof. The exact shape varies by supplier.
Can I use ridge cap on a single-slope roof?
Not really. Ridge cap is bent to cover two slopes meeting at a peak. A single-slope roof needs a trim with one leg on the panels and one face down over the high eave, which is what high side trim is.
Do I need closures under high side trim?
Yes. Outside foam closures fill the panel ribs under the trim so wind-driven rain, wasps and birds cannot get in at the top of the roof. Set them in butyl tape.