Insulated Sectional Steel Door

ThermoMark™ Models 5155 and 5255 insulated commercial sectional doors are extremely rugged and durable, with excellent thermal insulation qualities.  For commercial projects that require a door with strength, insulation and an overall solid performance, these doors are the ideal choice.

Featuring CFC and HCFC-free polyurethane foam insulation, Models 5155 and 5255 are available with two different levels of thermal performance.  The ThermoMark™ 5255 is rated with a U-value* of .0616 (R-value* of 16.22), while the ThermoMark™ 5155 has a U-value of .0825 (R-value* of 12.12).

The ThermoMark™ 5155 and 5255 both feature hot-dipped galvanized steel construction that is pre-painted prior to manufacturing with a two-coat system of polyester paint with a finished coat (includes primer).  The inside and outside skins are roll-formed and separated with a thermal break to eliminate thermal conductance.  Hinge locations have 20-gauge continuous back up plates for fastening.  The bottom astragal is a two-piece bulb-type astragal to be attached to the interior skin.  ThermoMark™ Models 5155 and 5255 section ends have end caps of 18-gauge hot-dipped galvanized steel, and a between-section joint seal is standard.

wayne dalton insulated sectional steel commercial doors

*Wayne Dalton uses a calculated door section R-value and U-value for insulated doors.

Door Options

Lite Options:



Insulated Vision Lites allow for visibility while maintaining security.  Full-view sections allow for maximum natural light and visibility.

Options & Accessories:


Broken cable devices

Chain hoist operation

Motor operation

Sensing edges

Photo eyes

High cycle spring (25k, 50k, 100k)

3" track option

Solid shafts

Perimeter weather seal

Special track designs


Vision Lites

Full-View Lites

Impact Panel:

Wayne Dalton's optional Impact Section replaces the traditional bottom section on doors exposed to damage from forklifts and other warehouse traffic.

Reduces downtime and costly repairs

Impact-Resistant composite skins surround an expanded polystyrene core

Fully adaptable to multiple door thickness with hinge and section adapters to provide a superior fit

Available for 21" and 24" sections

Available from 8'2" to 16'2" wide in one-foot increments

Highest Quality Standards

Max Width: 20' 2" (5155) and 26' 2" (5255)

Max Height: 20' 1"

27-gauge exterior steel

Polyurethane insulation, R-value* = 12.12 (1555) and 16.22 (5255) 

1-3/8" section thickness (5155) and 1-7/8" (5255)

Continuous steel strips for hinge attachment

Embossed stucco exterior with pinstripes

*Wayne Dalton uses a calculated door section R-value and U-value for insulated doors.

Model Comparison Chart
Door Construction:

1. Stucco steel back panels for aesthetics and easy cleaning

2. Hot-dipped, galvanized steel wrap-around end caps add strength, rigidity and long life

3. CFC- and HCFC- free polyurethane foamed-in-place insulation

4. Sound absorbing insulation makes door quieter in operation; reduces wind rattling

5.Two-coat, baked-on polyester finish makes surface virtually maintenance free

6. Bulb-shaped bottom seal remains flexible even in extreme cold to help keep the bad weather outside

IECC® Compliant:

The ThermoMark™ 5155 and 5255 meet IECC® requirements for maximum U-factor of operable fenestrations (2015 Section C402.4) with a 3rd party certified tested value of less than 0.37.  ThermoMark™ 5155 and 5255 also meet the ASHRAE 90.1 and IECC® requirement for maximum air leakage for fenestration assemblies (2015 Section C402.5.2 Garage doors) with a 3rd party certified tested value of less than 0.40.


White Pinstripe

Almond Pinstripe

Taupe Pinstripe

Brown Pinstripe

Custom Color:

This model is available with the TruChoice™ Color System.  Wayne Dalton's custom painting process that offers more than 6,000+ colors.

Online color swatches are only digital reproductions of actual standards and will vary in appearance due to differences in monitor and video card output.  These digital representations should not be used to finalize color selection(s).  Please reach out to us to discuss actual color samples to match your preferences.

Contact Information

2 Lukens Dr.

New Castle, DE 19720

Suite 600

Call Us: 1-888-927-3835


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