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Channel letter shop drawings: a checklist of what to put on them

The letter schedule, faces, returns, trim cap, backs, LEDs, power supplies, mounting, weep holes and UL label that a fabricator and an installer need, with a real channel letter section as the example.

By , owner of Zealot Signs · 5 min read
The short answer

Channel letter shop drawings should answer every question the fabricator and the installer will have: a letter schedule, a dimensioned elevation, the face, trim cap, return and back materials and colors, the LEDs and power supplies, the wiring and penetrations, the mounting into the wall, weep holes, where the UL label goes and the electrical load, with the client's approval and a shop sign-off on the sheet.

Key takeaways

  • Start with a letter schedule: every letter's height, width and return length, so the shop can cut and bend without measuring the art.
  • Call out every material with its thickness, gauge, depth and color: the face, trim cap, returns and back.
  • Show the lighting as a system: the LED modules, the Class 2 power supplies, where they live and the load in amps.
  • Show how it mounts: fasteners into blocking, the wall build-up, sealed penetrations, and who designs the attachment when an engineer is required.
  • Mark the weep holes and where the UL label goes, and get the client's approval and a shop sign-off before anything is cut.
On this page
  1. What a shop drawing is for
  2. The checklist
  3. By hand, or checking a workflow's draft

What a shop drawing is for

A permit set shows a reviewer the sign is allowed and safe. A shop drawing tells your crew how to build it and your installer how to hang it. Every question it doesn't answer becomes a phone call, a guess or a remake, so the checklist below is what a front-lit channel letter set should answer before it goes to the floor.

Section through a front-lit channel letterSection through a front-lit channel letter mounted flush on a wall: the face and trim cap at the front, 5-inch returns, the back against the wall, LED modules on the back, fasteners into the wall blocking, a weep hole in the bottom return, and a wire whip through the wall to a remote power supply carrying the UL label.WallPowerUL LABELTrim capFaceReturn5″ deepWeepLED modulesFastenerwhip
A front-lit channel letter, flush on the wall, drawn after the section on the Honeygrow permit set (PS-5, detail D-01). The list below is that detail's callouts.
  1. Face: 3/16 inch white acrylic (7328 or equal), white.
  2. Trim cap: 1 inch, white, fastened to the returns.
  3. Returns: .040 aluminum, 5 inches deep, prefinished white; the depth and gauge are the letter fabricator's call.
  4. Back: .063 aluminum.
  5. LEDs: white modules, UL recognized, spaced per the maker's chart for a 5-inch depth.
  6. Power supplies: Class 2, in a UL-listed enclosure behind the wall or remote; the count, wattage and location per the fabricator's layout.
  7. Weep holes: 1/4 inch at the low point of every letter, light-proofed.
  8. Fasteners: into the in-wall blocking, with the type, diameter and embedment per the sealed drawings.
  9. Wall: field-verify the build-up and seal every penetration.
  10. UL label: letters fed only by Class 2 wiring can carry one Electric Sign label, typically on the housing with the branch circuit power and the Class 2 power supply.

The checklist

  1. Title block and status

    The job, the sign ID, the revision and date, the scale, and a clear proposed-for-approval status until the client signs. A shop drawing that looks final before it's approved is how the wrong color gets built.

  2. Letter schedule

    Every letter with its height, width, stroke and return length, plus the overall size. The marquee letter shop set we publish puts the letter schedule, with return lengths and weights, right on its cover sheet.

  3. Dimensioned elevation

    The overall width and height, letter heights (cap height and x-height), spacing and the layout on the wall, with the mounting height to the top or bottom of the letters.

  4. Faces and colors

    The material, thickness and color of each face, with vinyl or paint numbers, not "match the logo".

  5. Returns, trim cap and backs

    The material, gauge, depth and finish of the returns, the trim cap size and color, and the back material.

  6. Lighting

    The LED module, its color temperature, the spacing for the return depth, and the module count per letter if the fabricator wants it.

  7. Power supplies and wiring

    Class 2 power supplies, how many, their wattage and where they go; the wire path; and every penetration and how it's sealed.

  8. Mounting

    The fastener type and pattern, flush or on spacers, the wall build-up and the blocking, and a pattern or template for the installer. Where the jurisdiction requires it, a licensed engineer designs the attachment.

  9. Weep holes

    Weep holes at the low point of every letter, light-proofed so they don't show at night.

  10. UL label and load

    Where the UL label goes and the estimated load in amps at the supply voltage, so the electrician can size the circuit and the inspector can find the label.

  11. Approval and sign-off

    The client's approval of the copy, colors and size, and a shop sign-off before anything is cut. The marquee set carries its shop sign-off on SH-1.

PS-5 of the Honeygrow permit set: the channel letter front elevation, the D-01 section and its callouts, colors and materials
PS-5 on the Honeygrow set: the letters' front elevation, the D-01 section and its callouts, with the colors and materials beside them. See every sheet
SH-1 cover of the marquee letter shop drawing set: a rendering, the letter schedule with return lengths and weights, and the shop sign-off
SH-1 of the marquee letter shop set: a rendering, the letter schedule with return lengths and weights, and the shop sign-off. See every sheet

By hand, or checking a workflow's draft

By hand, this is a designer redrawing the approved art in CAD, measuring every letter for the schedule and keeping the callouts in sync with the elevation through every revision. The shop drawings workflow draws the set from the approved drawings, with the letter schedule, elevations, sections and wiring tied to one geometry file, and your designer checks it before it goes to the floor.

Sources

  1. UL Solutions: simplified labeling for multi-housing electric signs
  2. International Sign Association: UL labeling update may complicate channel letter sign inspections
Questions

Questions people ask

What should be on channel letter shop drawings?

A letter schedule, a dimensioned elevation, the face, trim cap, return and back materials with colors, the LEDs and power supplies, the wiring and penetrations, the mounting into the wall, weep holes, where the UL label goes, the electrical load, and the client's approval.

How deep should channel letter returns be?

It depends on the letter size and the LED module, and the fabricator sets the depth and gauge. The Honeygrow letters used 5-inch .040 aluminum returns, with the LED spacing taken from the module maker's chart for that depth.

Where does the UL label go on channel letters?

Since UL's marking change of July 1, 2024, letters fed only by Class 2 wiring can carry a single Electric Sign label, typically on the housing with the branch circuit power and the Class 2 power supply, instead of a section label on every letter. Makers can still certify them as section signs, so check what your inspector expects before the install.

Why do channel letters need weep holes?

Water gets into letters at the face joint and the penetrations. Weep holes at the low point of every letter let it drain, and light-proofing keeps them from showing at night.

Who designs channel letter attachment?

The fabricator details it, and where the jurisdiction requires sealed drawings, a licensed engineer designs the anchors for the wall they go into. Give the engineer the letter sizes and weights.

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