Installation guide

Starter strip (or starter siding) is the first piece installed at the bottom of the wall. It establishes the line, pitch, and lock for every panel above it. If the starter is not level and straight, every subsequent course will show it.

1. 1

   Snap a level chalk line at the desired starting height, typically just above the foundation or water table.

2. 2

   Cut the starter strip to length and leave a 1/4" gap at each end for expansion.

3. 3

   Fasten through the pre-punched slots every 12–16" on center. Do not overdrive; the strip must float for thermal movement.

4. 4

   Use a level on every 4–6 ft run and shim low spots so the starter remains perfectly straight.

5. 5

   At inside corners, butt the starter into the corner post or J-channel without crimping the locking leg.

J-channel is a U-shaped receiver that captures the cut edge of a siding panel. It is used around windows and doors, at the top of walls, under eaves where undersill trim is not required, and as a trim for inside corners.

1. 1

   Measure and cut J-channel to fit each opening. For window/door tops, install the head piece first, then the sides, then the sill to create a proper overlap.

2. 2

   Leave a 1/4" gap at inside and outside corners and at butt joints to allow for expansion.

3. 3

   Fasten in the center of the nail slot, every 12–16" on center. Nails should be loose enough that the channel can slide 1/32" side to side.

4. 4

   At window and door heads, make two small relief cuts in the back leg and bend the J down over the top of the opening so water runs to the front and away.

5. 5

   When two lengths of J-channel meet, lap the upper piece over the lower piece by at least 1" to shed water.

Outside corner posts cover the seam where two walls meet and provide a pocket for the cut ends of siding panels. They must be installed plumb and fastened loosely so they can move with temperature swings.

1. 1

   Measure from the soffit or eave down to the starter strip and add 1/4" total (1/8" top and bottom) for expansion.

2. 2

   Install the post plumb using a level. Fasten through the top pre-punched slot, then check plumb before fastening the remaining slots.

3. 3

   Nail every 12–16" on center, centered in the slot. Do not drive the nail tight.

4. 4

   When stacking two posts on a tall wall, overlap the upper post over the lower by 3/4" to 1" so water sheds to the outside.

5. 5

   Cut the first panel of each wall so it leaves a 1/4" gap inside the corner post; the panel should never touch the post.

Undersill trim (also called finish trim or utility trim) is installed under eaves and at the top of a wall where the last siding course must be cut to fit. The locking tab on the trim engages the top edge of the panel so it holds securely without exposed fasteners.

1. 1

   Install undersill trim along the underside of the soffit or fascia, level and parallel to the starter strip.

2. 2

   Fasten every 12–16" on center, centered in the slot, and leave 1/4" gaps at corners and butt joints.

3. 3

   Measure the final panel height from the top of the locked panel below to the bottom of the undersill trim.

4. 4

   Cut the panel to height and crimp the top nail hem or locking edge so it snaps into the undersill trim.

5. 5

   Install the final panel, lock it into the course below, then push the top edge up into the undersill until it clicks.