Engineered to install

Why this page exists

The Shim Jack, the Starter Channel, and the tilt-up panel are the structural backbone behind every Linea Motion door. They're the difference between a system designed to look good on day one and a system designed to hold its line through ten years of commercial use.

The Shim Jack

• Distributes operational load the forces created every time a door swings, slides, or pivots into the structure rather than concentrating it at hinges and tracks.
• Absorbs construction tolerance up to 3/4" on the ThinWall product line, plus the additional adjustment built into the Trimmed snap-trim so the door arrives plumb regardless of how the wall was framed.
• Maintains alignment over time the geometry resists the long-term creep that causes most commercial doors to bind after a year or two of use.

The Starter Channel

• Establishes the install reference plumb, level, and square so the installer isn't finding their own datum on every opening.
• Decouples the door frame from rough-opening irregularities the variance that always exists between drawn and built walls is absorbed before the frame goes in.
• Carries the head and jamb extrusions into a predictable load path, reinforcing what the Shim Jack does downstream.

Pre-Glazed Tilt-Up Panels

• Glass is captured in the aluminum perimeter at the factory under controlled conditions clean edges, consistent setting blocks, no jobsite dust or contamination at the glazing line.
• The panel tilts up against the Starter Channel datum and lands on the Shim Jack, so alignment is set by the structural reference, not by the installer eyeballing it.
• Fewer trades on site, fewer steps in the install sequence, and the punch list shrinks because field glazing callbacks are removed from the project entirely.

Why we built them

What it means for the project

For architects

For builders

For owners

Most aluminum door systems compete on profile and finish the parts you see. The parts you don't see are where most systems fail over the life of a building: out-of-square frames, doors that bind after a year of settling, hardware that loosens, panels that need shimming on every install. Linea Motion's installation engineering, the Shim Jack, the Starter Channel, and our pre-glazed tilt-up panels, is the part of the system you'll never see and it's the reason our doors stay aligned, install predictably, and serve longer than the alternatives.

The Shim Jack is Linea Motion's proprietary structural integration between the door panel, frame, and surrounding wall. It performs three jobs simultaneously:

None of this is visible in the finished installation. That's the point.

The Starter Channel is the perimeter aluminum extrusion that goes into the rough opening before the door frame, the head, or the glazing. It does the first-stage alignment work so every subsequent component installs against a known datum:

The Starter Channel and the Shim Jack work together: the Starter Channel handles the install datum, the Shim Jack handles the long-term load and alignment. Both are present in every Linea Motion install.

On the ThinWall system, the fixed glass panels arrive pre-glazed from our Omaha facility and tilt up into place against the Starter Channel and Shim Jack already set in the opening. No field glazing, no glass handling at height, no separate glazier trip. The panel goes from delivery crate to plumb in a single operation:

The tilt-up sequence is what lets the ThinWall system absorb up to 3/4" of wall variance without field shimming a unit that arrives complete, lands on a known datum, and locks into a structural backbone designed to hold it there.

Linea Motion was started inside a manufacturing company that had been making doors for 20+ years before the Linea brand existed. All three features came directly out of that experience the engineering response to every callback, every job-site complaint, and every "the door doesn't close right anymore" service ticket the team had seen across two decades of commercial install work. They exist specifically because we knew where competitive systems were failing and decided to engineer past those failure modes.

You can specify Linea Motion knowing the system performs to its drawn geometry through the warranty period and well past it. The Shim Jack and Starter Channel are part of why our shop drawings match real installation conditions even when the field walls don't quite match the architectural drawings. More for architects

Faster install, fewer site adjustments, fewer punch-list items at closeout. The same tolerance absorption that helps the architect helps the GC during install you don't end up shimming every opening to make the panel close. More for builders

Doors that hold their line. The buildings that have specified Linea Motion for years banks, offices, salons, places of worship come back for repeat work because the original install is still operating cleanly. The Shim Jack, the Starter Channel, and the pre-glazed tilt-up panel are a meaningful part of why.