How to Install J-trim on Steel Buildings

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The edges of metal siding installed on pole barns and metal sided buildings are covered by J-trim.

J-trim installs on steel-sided buildings, such as pole barns and commercial buildings, as the finish trim to steel siding. Similar to J-channel used with vinyl siding, J-trim is nailed to the building's framing at the top edge, and along any interior corner seams to hide the raw edges of the siding. When complete, the J-trim neatly finishes off the siding, covering any cut, raw or sharp edges to prevent damage from water penetration.


Step 1

Attach the J-trim along the line that will form the upper edge of the metal siding. The metal siding will slide into the J-trim, so install the channel with the opening of the "J" facing the direction of the siding. Install the trim by nail the longer side of the "J" to the framing lumber with the washer head metal siding nails.

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Step 2

Nail the J-trim horizontally along both sides of any interior corners. At an interior corner, the siding will slide into the trim to hide the rough cut edge.


Step 3

Nail the J-trim to the outer and inner edge of the soffit area. The pieces of metal soffit will lay into the J-trim, and cover the open area of the soffit. Nail the J-trim so that the open areas of the "J" point toward one another.

Step 4

Slide a piece of trim, which is then installed under or lower than another piece into the piece which is above it. The upper trim must cover the joint so that water can't drip down into, and behind the trim.


Step 5

Install any joints in the trim so that the pieces of trim overlap one another by 1/2 inch. Lower pieces should slide into the upper pieces, and horizontal runs should also overlap so that no water can penetrate the molding.

Step 6

After the J-trim is installed, the metal siding is installed as described above, hiding all but the bottom edge inside J-trim and outside corner molding around the building's perimeter.



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