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All Commercial Doors & Grilles

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New Products

Check out our latest innovations and see what's new!

New Products

Rolling Service Doors

Choose our Service Door when you need an interior or exterior closure option that is secure, durable, customizable and compact.

Standard Door

High Performance Products

Whether you need advanced performance for security, productivity or air protection at the opening, we can suggest the right door or grille to meet your performance needs

High Performance

Max Protection Doors

Whether you need doors that can withstand hurricanes and high winds, or protection from the threat of riots and looters - our Max Protection Doors can meet your needs.

Max Protection

Insulated Doors

We didn't invent the insulated door – but we perfected it. Choose our market-leading energy-efficient insulated doors in extreme environments or anywhere you want to save on energy costs and go green.

Insulated

Fire Rated Products

Our Fire Rated Products provide the highest level of life safety and fire protection available with the lowest cost of ownership in a modern, easily integrated package.

Fire Rated

Security Grilles

No matter if you need it side folding or vertical coiling, our grilles provide both security with visual access for interior and exterior openings.

Security Grille

Rolling Counter Door

Commonly utilized in cafeterias, concession stands and ticket booths, Counter Shutters, also known as Counter Doors, provide accessibility and security in interior and exterior finished wall openings

Counter Door

Side Folding Doors and Grilles

Easily and quickly transform a large room into two or more sections for security, privacy or unparalleled sound control with our Accordion Partitions. Secure storefronts and more with our Side Folding Grille options that blend effortlessly into any design.

Side Folding

View Operator Information

There are many factors to consider when choosing how your door will operate. How fast you want it to open, how many times a day will it cycle and if there is power available are just a few of these factors. Here, you will find information on each of our available operators.

Operators

Quick Access Download

Experience the convenience of downloading all your essential documents in one place!

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Custom Commercial Doors

Regardless of the size, scope or scale of your project, we'll create a door made to your precise dimensions and specifications.

Custom

Loading Dock Doors

If you have a shipping and receiving area of any size, your loading dock doors have a significant impact on your business.

Dock Doors

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From stainless to galvanized steel, or daffodil yellow to ruby red – our materials and finishes options are sure to complement your design.

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Industry Applications

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Learn About Our Roll Up Grilles

Roll Up Security Gates keep areas safe, can be customized for special design projects, and require almost no maintenance.

Parking Garage

Auto Dealerships

Keeping auto dealerships safe and secure

Auto Red

Learn About Bar and Restaurant Closures

Protecting your bar or restaurant is crucial. We take off some of the stress with the SteelWeave™ Metal Mesh Grille.

Bar Restaurant

Cannabis Industry

In the cannabis industry, keeping your staff, facility, and products secure is a make-or-break task. You know the importance of designing a building that’s secure for high value manufacturing and distribution, and we’re here to help.

Cannabis No Circle

Fire Station Industry

Every second counts when there is a fire that needs to be fought.

Firehouse

View Our Healthcare Closures

Choose from a selection of Fire Doors, Overhead Doors, Insulated Garage Doors, Rolling Counter Shutters, and more! Find the best safety solution with our products.

Hospital

Government Operations

No matter the operation, government facilities should always be fitted with the best security measures.

Government Red

Learn About School and University Solutions

Choose from a selection of convenient solutions such as Accordion Folding Doors, Fire Doors, Security Doors, Side Folding Grilles, and so much more! Contact our design specialists with design ideas.

School

Learn About Our Retail Closures

Learn what type of Rolling Door and Security Door is right for your security needs.

Retail

Learn about our pharmacy closures

We provide custom security solutions to protect your pharmacy and preserve your medications against forced entry and theft.

Pharmacy

Warehousing

We're here to help you find the perfect doors for your needs, whether you're building a new warehouse or outfitting an existing space.

Warehouse
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Installation & Maintenance Manuals

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You focus on taking care of your customer. We focus on taking care of you.

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Check out our wide selection of overhead door operators designed for use with our rolling doors, shutters and grilles.

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We provide stocked and custom parts to get your rolling doors back to their peak performance.

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Enhance the performance or aesthetics of your rolling door, grille or counter shutter.

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Rolling door and grille installation videos.

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Roll-Up Door Installation

Before getting to work on your Cornell roll-up door installation, view our process.

RollUp Door Install
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Customization

Explore Customization Ideas

Learn About Our Materials & Finishes

From stainless to galvanized steel, or daffodil yellow to ruby red – our materials and finishes options are sure to compliment your design.

Finishes

Check Out Our Product Options

Standard offerings are, well, standard. And we know you spend most of your days creating designs that are decidedly not standard. That’s why all of our doors and grilles are built to order, so you can build a door that is as unique as your design.

Options

See our RAL Colors

See our full range of standard RAL colors available for powder coating onto the different components of our doors.

Colors and Finishes
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Inspiration

Gain Inspiration for Your Next Project

Check out the Project Gallery

See some projects that contain our products and learn why our customers are happy they chose us.

Project Gallery

Watch our Videos

Learn more about our products and our company - watch our videos!

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Architect Portal

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Technical Assistance

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Frequently Asked Questions

Check out our Top 10 most asked questions.

Questions

We Draw For You

Looking for help? Upload your drawings or specifications and one of our Design Specialists will deliver standard drawings for you.

Draw for You

Check out our Custom Door Solutions

Is your project far from standard? Fearful that your design can't be achieved? Our team of Design Specialists are experts when it comes to customized projects.

Custom

Design Tools

Choose from a variety of tools available to you to assist with your design needs.

Design Tools

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LEED Information

Find out how Cornell's product components measure up on the LEED rating system.

LEED

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Find out what building codes and listings our products meet and gather the necessary documentation for your project.

Codes and Listing

Meet the Team

With over 100 years of experience combined, our Architect Design Team and Products Representatives are here to help you choose the perfect door for any application.

Meet the Team

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View all of our operator manuals in one convenient place.

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  1. Home
  2. Blog

Find Out What's New with Rolling Doors and Security Grilles - Welcome to Cornell's Blog!

When it comes to Overhead Rolling Doors and Grilles, we are the experts in innovative door solutions!

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Understanding Rolling Door Thermal Resistance and Air Leakage

March 01, 2018 by CornellCookson

Thermal resistance is a huge factor that affects the energy performance of insulated roll up garage doors when they are in the closed position. Thermal resistance is measured using R-Value and U-Factor.

Air Leakage on the other hand refers to the seal at the overhead door guides, head and hood while the rolling door is in the closed position. Without the proper seal, air will have the ability to pass through the rolling door. Regardless of how high the R-Value of an overhead coiling door may be, that is irrelevant if an improper seal allows air to pass through.

Insulated Roll Up Garage Doors Air FLow

The Shocking Reality of R-Value vs. U-Factor of a Rolling Door!

R-Value may seem like a pretty straightforward measurement to determine the quality and energy performance of insulated roll up garage doors, but that is not always the case. Unfortunately, the R-Value is often misunderstood and given more credit than it deserves. The technical definition of R-Value is “the inverse of the time rate of heat flow through a body from one of its bounding surfaces to the other surface for a unit temperature difference between the two surfaces, under steady state conditions, per unit area.” Doesn’t this sound like an extremely technical in depth scientific calculation that will help you determine the best insulated rolling door for you…… well it’s not that cut and dry. In plain English, the R-Value is the capacity of an insulating material to resist heat flow. The higher the R-Value, the greater the insulation power. With that being said, we would like to share with you a common misconception of R-Value and how accurate it really is.

Insulated Roll Up Garage Doors CIty

Insulated Rolling Door Myth:

The most common R-Value myth is that it is the best indicator of energy efficiency for an insulated coiling door.

Insulated Rolling Door Reality:

The reality is that R-Value is a good measure for layers of wall insulation, not products comprised of multiple components.  This means that stated R-Values for insulated roll up garage doors only reflect the insulation in the slat cavity’s resistance to heat transfer.  An insulated rolling door slat on an otherwise breezy roll up door assembly is the equivalent of putting a wool hat on when you’re wearing shorts.  One component might be right for snow, but the whole outfit isn’t.  This is just like a commercial garage door that has excellent insulation but an improper seal around the roll up door guides, head and hood, which then allows for air leakage. An insulated overhead door with air leakage completely voids a high R-Value. And, R-value is calculated, not tested – meaning that the commercial door insulation within the roll up door slat itself should perform at that level, but it isn’t tested as a complete assembly (hence the seal around the door guides, head and hood not being included in the measure of R-Value.)

Insulated Roll Up Garage Doors Red

Energy Efficient Overhead  Door Fact:

U-Factor measures the rate of heat transfer, and is appropriately applied to the thermal efficiency of windows which, similar to insulated roll up garage doors, are assemblies comprised of multiple components. 

Now that you understand why U-Factor is a better energy performance indicator, lets discuss the details of it.  U-Factor is a tested value of heat transfer via conduction and radiation. The underlining and bolding of tested was not a typo. Unlike R-Value, the U-Factor it is an independently tested value – that’s a huge deal!  Also, the testing is performed on the full assembly, not just the insulation in the slats. Both of those items make the U-Factor a much more relevant number to use when considering what rolling door to purchase. That means that air leakage is taken into consideration when testing for U-Factor. And don’t forget when purchasing your next insulated roll up garage doors, the lower the U-Factor the better!

Insulated Roll Up Garage Doors Single Door

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 Cornell is the industry leading rolling door, security grille and closure product experts since 1828.
To inquire how Cornell's long history of innovation and customer service can help you with your next rolling door project, call 1-800-233-8366!

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