Why is Metal Snow Retention Better Than Plastic?

Every once in a while a customer will ask us why they should purchase our metal snow retention rather than the plastic ones they see. We typically don’t like plastic snow guards for many reasons.

The first reason is because of the type of adhesive used to attach plastic snow guards. Through our testing, we have found that failure exists when freeze-thaw temperature is introduced to the adhesive.
The second reason, they crack and deteriorate when continuously exposed to the sun’s ultraviolet light (UV). See the images below.
The third reason, manufacturers don’t warranty failure when the plastic snow guards pull apart from the adhesive.
From all of these reasons this why metal snow retention is a much wiser choice!


plastic vs TRA

TRA Metal Clamp-on vs Plastic Guards


Most plastics eventually become brittle when exposed to the sun.

Because of its tough nature, metal can withstand the sun’s destructive UV rays. Over time plastic will crack and deteriorate when continuously exposed to the sun.


Cracked, Brittle and Broken “Plastic Snow Guards”


TRA’s metal snow retention systems are attached securely using a variety of durable and strong mechanical methods.

Unlike metal, plastic snow guards are usually attached to a roof using caulking, which is likely to fail for the following reasons:

  • If the roof is dirty or wet when installing this makes the adhesive not adhere properly. When have you ever seen a truly clean roof?
  • More common than not snow guards are installed at temperatures below 40 degrees.
  • Caulking cure time can be more than 30 days above 40 degrees.
  •  Over time plastic will crack & deteriorate when continuously exposed to the sun UV.


1 rail snow guard for metal roof

TRA C21Z Clamp-on with Ice Flags 


Unlike plastic, metal lasts.

Plastic snow retention manufacturers generally do not warranty the attachment just plastic snow guard. If a plastic snow guard fails, the architect or contractor becomes liable for the damage to property /or human life.

Next time you are near a roof with plastic snow guards, see if any are missing and let us know!

We recommend only metal snow retention because we know it can properly protect those in and around your home. For extra protection, we engineer from the sheathing up with the fastener and provide a warranty on the entire snow retention system. Before installation, we engineer a specific layout to see that the system is exactly what you need for your specific location and weather. Contact us with any of your project details and we’ll provide you with the best snow defense system that’ll get you ready for winter.


Thanks to you, our customers

tra snow and sun

The first goal I had when establishing TRA was to prevent injury and needless death to people by creating snow guards that would not fail.  I wanted to be sure dangerous avalanches of snow and ice could be stopped by engineering each snow retention project.  That original objective of safe, dependable, complete systems has carried over to all products we manufacture – solar mounting products, flexible ventilation and snow retention.  Thank-you for your trust in us as we work with you to continue this paramount objective of safety and dependability.

I hope that we are doing a good job in our mission:

  • To offer the highest quality snow retention, solar mounting systems, flexible roof flashing and ventilation products made from superior materials that provide the ultimate in protection, durability and dependability.
  • We strive daily to provide customized service, exceptional engineering, superior manufacturing, and resourceful solutions for each customer, focusing on the unique requirements of each project.
  • Our team is united, innovative and dedicated. Each employee pursues excellence in each company endeavor and realizes that maintaining the good reputation that took decades to establish depends on them.
  • We are not content to simply be successful, but strive to set new and higher standards in all that we do.

As the owner of TRA Snow and Sun, I am responsible for the quality of our products, the service to our customers, and the care of our employees.  Each of these things is supremely important to me, but none are possible without YOU.  The customized service that we provide is dependent on YOU, our customer, working closely with us to engineer systems which are superior and dependable.  Each project is unique and we appreciate your efforts to make your individual project the best possible.

In this time of Thanksgiving, I thank YOU for the opportunity to provide the world with dependable roofing systems.  Thank YOU for your partnership and your trust in TRA Snow and Sun.

Please contact me at any time.  I welcome your suggestions and ideas.

Terry E. Anderson



Featured Spotlight “Snow Retention – D Bracket”

 Snow Bracket D

Snow Bracket™ D

A question once asked – On the roofs of many houses, along the eave, there are…best as I can describe it… shaped thingies. I’ve seen others that look octagonal and yet others that are round. I’ve seen them on steep roofs and not-so-steep roofs. My bank even has them. They look great, but do they do anything? 

The answer is yes. What you’re talking about are called snow guards for retaining snow on the roof. When snow and ice accumulate on the roof, they are pulled by gravity and want to slide down the slope of the roof. A well-designed snow retention system is intended to hold the snow on the roof so that it can melt in place.

At TRA Snow and Sun, we engineer and manufacture over 54+ variations of snow guards, and always welcome custom pieces made just for your roofing project. Yes, 54 may seem a lot, right? And your right it is, and here’s why – every roof design can be complex and is different from material, slope, shape, size, pitch, valleys, etc.., and ground snow loads vary significantly from one area to another. This is why we make several different engineered (from the fail point of the system) snow guards tailored to each unique roof designs for every roof type, new or existing, and in many styles that differ in form and function.

trasnowandsun, snow retention, solar mounting systemsSecure Attachment

trasnowandsun, snow retention, solar mounting systemsSuperior Strength

trasnowandsun, snow retention, solar mounting systemsVariety of Material Types


snow clips, snow guards, snow bracket

Our first featured spotlight for this month is our unique Snow Guard Bracket D. The Snow Bracket™ D, a permanent snow retention system that is aesthetically pleasing on asphalt shingle roofs. Choose between a vast array of painted powdered colors, available in standard mill finish of steel, copper or aluminum. The Snow Guard Bracket D fastens to roof sheathing to any new construction of an asphalt shingled roof.

Asphalt shingle roofs very common in the United States and it is important you have a Snow Bracket™ that fits the roof type you are installing the product one.

  Snow Bracket™ D

snow bracket d snow guardSnow-Bracket-D Maple-leafSnow-Bracket-D Sunburst



Length: 10″
Width: 1 3/16″
Height: 3″


• Paintlok Steel: 16 ga
• Copper: 48 oz (ASTM B152)
• Stainless Steel: 16 ga (ASTM A240)



• Zinc Plated
• Powder coating available in many Colors

*We can provide Paintlock brackets unpainted BUT they must be painted before installing or rusting will occur. Also, available with attachments see images to the left with Maple & Sunburst.

Custom Designs and Engineering

At TRA Snow and Sun, we engineer and lay out each project free of charge using many factors specific to your roof. We then provide you with the snow retention plan, layout and product detail. TRA Snow and Sun representatives will work with you to design the most efficient snow retention system. Fill out our Snow Retention Checklist to get started.


All Snow Brackets have been tested from the fail point of the system.

Retro-fit Snow Retention. What to do?

One of my older relatives used to say, when confronted with a dilemma, “What to do, what to do….”  It made me chuckle!

But, this phrase describes a dilemma for people confronted with snow and ice avalanching off their already installed roof.  They want to keep the snow up there

snow clips, snow guards, snow bracket

rather than down there

Snow Avalanche Off A RoofFalling Snow in Park City, UT

but what is the best solution?

First of all, retrofit is similar as well as different from new construction.  Basic questions need to be answered for new and retrofit construction.

  • What is the slope?
  • What is the snowload in the area?
  • What type of roofing product is being used?
  • What type of sheathing is under the roofing material?

For retrofit, snow retention installers don’t have the luxury of applying the snow retention devices as the roofing material is installed in a new project.  This is when “What to do, what to do…” might be heard under their breath!

How do you keep snow and ice from falling off while also maintaining a water-tight system when the roofing is already on the roof?  How hard is it to do this?

Contractors need a simple and effective solution.

For asphalt shingles, simulated shake, and other similar roofs, using TRA’s H Snow Bracket, there is no need to pull back the headlap to install a device. Butyl or caulking can be applied on the surface of the roofing product, then the bracket is installed directly into the sheathing using screws.  A clip is then placed over the screws.


Snow Bracket H

Easy.  Effective.

The reason this system will work on retrofit is because TRA’s engineering is done using the specific factors as mentioned above.  When installed using the engineered layout, the roof will now hold back the snow and ice that would have fallen off, damaging people or property below.

At TRA Snow and Sun, we help you find an Engineered Solution.  Call us for a free layout, provided within 2 working days.

Snow Bracket H

Designed for most roof types

Available with or without fastener cover clip

Can be powder-coated to match roofing material

Available in 16 g steel, 48 oz copper, 26 g Cor-Ten, 16 ga stainless steel, .063″ aluminum

Finishes – Electro-galvanized, hot-dipped galvanized, mill finish aluminum, copper or Cor-Ten

Power-coating available in many colors.

When Strength Really Matters

snow falling on carsIce_dam_slate_roof

Keeping snow and ice from avalanching off a roof requires a system of superior strength.  When strength really does matter to save lives and prevent damage to property, how does a home or business owner know what snow retention product is strong enough?

How does someone decide what product measures up?

How does one decide the best method of installing a safe and reliable roof snow retention system?

If your answer to these questions is, “I can find that out.  I’ll just look it up online under building codes or ask my roofing contractor.” 

Well, good luck.

There are NO codes for roof snow retention!  None.  Nil.  Nada.  (Our owner, Terry Anderson, is serving on a committee right now to finally establish standards.  Watch for updates on this in the future!)  If a contractor starts sitting codes or standards, be wary.  The contractor might have his own standards, and we sure hope they all do, but there are no national or international standards for snow retention.

This makes it very important for owners, architects, engineers, and contractors to take extra care when designing a snow retention system. At TRA Snow & Sun, we seek to offer high-quality snow retention devices ENGINEERED for the unique snow & ice and building conditions relative to each specific project.

Snow retention as a science has emerged as a technological know-how for human safety. The laws of physics have to be used when holding back lots of destructive snow and ice. Annual assets and personal damage from destructive sliding snow and ice is in the millions, however, the price of a human life is incalculable.  If someone dies as a result of no snow retention or faulty snow retention, the liability threat to household owners and business proprietors is astronomical.

By retaining snow on the roof of a building and allowing even snow melt-off, injuries to residents/guests and property below the roof of a building can be avoided, saving money and limiting the possibility of personal loss. By installing snow retention you can:

  • Prevent danger to residents and guests.
  • Prevent costly roof and property damage.
  • Maintain safe access, keeping entrances/walkways free of snow and ice.
  • Promote energy efficiency by retaining snow which is a good insulation blanket.
  • Trust in the best with the highest quality snow retention devices.

How does one avoid the potential pitfalls to a bad snow retention product?

It can get perplexing with several hundreds of different snow guard types and designs to consider from. With a TRA snow retention system, you know you’re safe because we have gone through extensive product testing. Our products are built to last to the fail point of the snow retention system, not just the product. Unlike other plastic type snow guards that turn yellow and fail over time, TRA’s snow retention systems are superior in strength. Our superior snow retention is designed to manage snow migration on any type of roofing is made of stainless steel or brass.

plastic vs TRA



In simple terms, a first-rate snow retention product coupled with a reliable and safe FREE engineered spacing layout will help lessen the legal responsibility related to the unexpected slid of snow and ice from roofs. All requesting clients can receive free engineered layouts within 2 working days for each project’s specific requirements. For a free layout, data sheets, specs & quote contact us at 855-542-1861.


TRA Division 07 7253 Snow Guard Specifications Have Just Been Updated

Spec Logo

TRA Snow and Sun knows how important it is that specifying roof snow retention be as worry free and easy as possible for architects, designers and homeowners. So over the last several months we worked hard with our partners to improve the quality and ease of creating a good, safe, and specific roof snow retention specification.

We are proud to announce that our Division 07 7253 Roof Snow Retention specifications have just been enhanced and updated!

Designers and contractors can now read and download the snow guard specifications using MasterSpec or with SpecLink. They can also contact TRA Snow and Sun via phone or through our contact page at anytime and we will e-mail the new snow guard specifications which can be merged into master specification documents.

With our updated snow guard specifications, designers  have the necessary knowledge base to create the perfect snow retention system for their unique project design. We have made it as easy as ever!

TRA Snow & Sun roof snow retention products provide superior benefits to building designers and contractors because they get a safe SYSTEM, not just a good product. We test and engineer our products based on the components of their specific roof system (snow guard, sheathing, attachment, slope, snow-load, etc.). This dramatically decreases the designer or contractor’s liability!

TRA provides a FREE, no obligation, ENGINEERED LAYOUT within 2 business days – 855-542-1861. Website:

Choose from zinc-plated steel, copper or stainless steel. All steel can be powdered coat to match the roof color. Roof types include metal panel, asphalt & cedar shingles, corrugated metal, flat granule metal, simulated slate, single ply, slate, tile & wood shake.

The Vandelay Project

Snow Retention Case Study – Providing Engineered Snow Retention Solutions for HALF THE COST!

TRA Snow and Sun solves problems!  It’s not just our motto to provide Engineered Solutions.  We really DO IT!

On an addition to a home in Northwest Montana with a high snow load (100 psf); how do you retain snow on a cedar shake roof with a 12/12 pitch, whilst keeping it economical, aesthetically pleasing, and in line with the existing design?

After reviewing their options, Vandelay Construction was ready to order from a competitor, but was concerned about the high cost of the snow retention system, so they did one last internet search of roof snow retention.  They found a project with TRA Snow and Sun snow retention in Bozeman, Montana, liked our product and designs, and contacted us.

Using the information the contractor provided to us, we increased the thickness of the copper from the standard ¼” to 3/8” and designed a 3 rail snow retention system (D3H Deck Mount Snow Fence) specific to the project – cedar shake, 12/12 slope, copper, attaching to 16” OC rafters.  Copper was used to match the decorative end caps on the heavy timbers in the construction of the building.

Not only did the homeowners get a beautiful, warrantied system, but OUR SYSTEM WAS HALF THE COST OF OUR COMPETITORS.

We love the result.  See for yourself.



At TRA, we provide Engineered Solutions to all kinds of problems.  Let us help you with your snow retention needs!

Should Your Building Have Snow Retention Devices?

The Tell-Tale Signs in Spring That You Should Install Snow Retention


The winter is slowly fading into Spring, but as the snow and ice melts off your roof, there might be some signs that you need snow retention:

Are you noticing large pieces coming off in big chunks?

Do you hear it slipping? (This can be pretty loud and frightening when it happens unexpectedly!)

Are pieces of your gutter coming off due to ice tearing it off as it slipped off your roof?

Are there high spots of snow and ice piled at the eave line on the ground? This might mean that snow or ice has come off that place during the winter.

If you answered yes to any of these questions, continue reading.

People die due to snow and ice sliding off roofs. This is extremely tragic and often avoidable. Use roof snow retention for these reasons:

  1.  Damage/Injury – People and property can be struck by snow and ice falling from the roof. Property damage and injuries, even deaths can occur when snow is not properly retained on a roof.
  2.  Limited Access – Entrances to buildings can be blocked by snow and ice that falls from a roof.
  3.  Roof Damage – When snow and ice masses slide off a roof, costly damage occurs.

Damage from Slidding Snow & Ice

It is especially important to install snow retention above:

  • entryways
  • walkways
  • gathering spots
  • parking lots
  • drive-through areas
  • expensive landscaping
  • ground mounted mechanical
  • roof protrusions such as plumbing vents

Can Your Building Support the Weight of Snow Retention?

You might wonder if your roof can support the weight of snow and ice staying on the roof. If your home is less than 40 years old, the answer is probably yes.

During the 1970-80’s, most states adopted building codes that required structures to support the weight of the building materials (dead load) and the weight of the snow, ice, water, people, etc. (live load). By the year 2000, international building codes were universally adopted with similar standards. So, if the structure was built post 1975, you are unlikely to have any structural problems when keeping snow on the roof (it also helps insulate your roof, saving heating costs!).

Snow Retention – The Invisible Code

Snow retention codes do not seem to be a priority in the United States’ roofing industry. But it is very common to see snow and ice sliding off of a metal roof’s slippery surface. Snow and ice crushes cars, and damages the roof, gutters, and landscape.  In some cases, snow and ice cascading off roofs has killed people. Codes for snow retention systems are essential to protect people and property from sliding ice and snow.

There are many reasons snow retention systems fail and why we need codes in place.  Some examples are:


snow retention system

This snow retention system was not engineered for some variable of the project that caused it to fail.

The snow guard was not strong enough to hold the load it was carrying.

Anyone can cast a wax snow guard, spread some adhesive on the bottom, and tell the consumer how to install it without any testing of the product or the system. Codes would provide a standard to ensure adequately designed products are utilized.


Roofing material is inadequately secured for the shear created by sliding snow.

If the roofing material is not securely fastened to the deck (specifically on standing seam metal roofs), added weight can cause the standing seam metal roof to slide right off, along with the rest of the roofing material and snow retention system. There is a code requirement in place for wind uplift on standing seam metal roofs, but not for shear strength.

Screws or fasteners pull out.

sliding snow and ice

Sliding snow can be incredibly dangerous.

When installing snow retention on roof sheathing, the thickness and type of the sheathing determines the fastener pull-out strength.  If one is installing a snow retention system on 7/16-in. OSB board, the fastener will fail more quickly than when using ¾-in. plywood.  (See chart below.) When designing a layout for a project, many snow retention manufacturers do not test for these variations.  If the snow retention system was designed for ¾-in. plywood and the project is using 7/16-in. OSB board, the whole system needs to be redesigned.

The fastener does not penetrate the sheathing.

If the fastener/screw is not penetrating the sheathing, the snow guard will not have the holding strength for which it was designed.




plastic snow guards

These plastic snow guards fell to the ground because the adhesive did not bond properly

When using an adhesive, if the surface is not free of dust, dirt, oil, or waterproofing; or it is not clean and dry, the adhesive will not adhere properly.
If the temperature is not above 50 degrees F, the sealant will not cure. If a load is placed on the snow guard before the 28-day cure time, the snow guard is more likely to fail. (This is according to the Technical Data Sheet  for SB-190)


The system is not designed for the roof slope and snow load.

When designing a snow retention system, factors change from project to project: the slope, roof type, sheathing type, and roof snow load.  If the snow retention system is not engineered for the variables of the project, it can fail.
Most snow guards are not tested to the fail point of the system.

Many snow guard manufacturers claim theirs are tested, and many of them are, but they are not tested to the fail point of the entire system.  The product may be tested to maintain its shape, but was it tested to stay on the roof?  It’s great if the product stays in one piece, but not if the fastener fails, the adhesive fails, and the sheathing fails.

snow retention code

A snow retention code needs to be put in place to help prevent injury to people and damage to property.


The product was not installed to manufacturer’s specifications.

The manufacturer’s instructions need to be followed meticulously in order to ensure safety and to keep warrantees in effect.  Many manufacturers have specific torque requirements, placement, and maintenance instructions.  If these instructions are not followed, the system can fail and the manufacturer is not at fault.

Obviously, there are valid reasons why the United States should establish codes for snow retention on roofs.  Why hasn’t this happened?  A few reasons could be:

  1. Snowfall occurs in certain areas of the country but not nationwide; therefore, the demand for codes is minimal.
  2. Not many deaths occur due to ice and snow sliding.
  3. Property damage is localized.
  4. The insurance industry is not pushing for this type of code.

There are many other codes in place to protect people and property; so why not for snow retention?  We have codes for wind uplift and ICC test standards for product failures due to wind and moisture penetrations, to name a few.  How many life threatening events need to occur before we do the right thing when it comes to a code for snow retention on roofs?

It’s time to make the invisible snow retention code visible.


  1. Surebond Technical Data Sheet SB-190.

About the author

Terry E. Anderson has been in the roofing industry for over 35 years. He is the owner of Anderson Associates Consulting and president of T.R.A.-MAGE, Inc., a manufacturer of roof snow and sun accessories. Anderson was sought after to solve tile roof problems, eventually researching solutions to the frequent structural damage caused by sliding snow and ice. Traveling to Europe, Terry studied how the roofing industry there successfully dealt with snow and ice issues. Using his years of experience and research, he coauthored Concrete and Clay Tile Roof Design Criteria for Cold and Snow Regions. Anderson founded T.R.A. Snow and Sun, now in partnership with MAGE and known as T.R.A.-MAGE, and is recognized as a leader in snow retention systems. He is a member of RCI, WSRCA, and on the technical committee for the Tile Roofing Institute (TRI).

Published: Interface Dec 2011

Download (PDF, 407KB)

Snow and Ice on Sloped Roofs: Shed it or Keep it on?

How would you answer this question? If you are like most roofing consultants, you would reply based upon a number of factors.  One factor would be your experience as a roofing expert.  Another would be where you live and work.  Another factor would be your training.  If you are from North America you would probably respond “shed it off.”  Our approach in North America is to use a metal roof with a steep slope that will allow the snow and ice to slide off.  Why do we design this way?  The primary reason is a fear of having the building collapse under a heavy snow load.

As I design roofs today in ski resort areas, I use one of the above types of roofs and plan to keep the snow on.  I vent the roofs for many reasons:

If you lived in Europe, however, you training and experience would be notably different.  For instance, a roofer in Germany must apprentice before he can become a journeyman. (This compares to our weekly union program that involves very little training on sloped roofs in snow climates.)  A German apprentice’s training includes classroom and onsite work.  Manufacturers sponsor training and provide detailed reference books and manuals.  One key difference in industry’s approach to snow on roofs is that keeping snow on the roof is something that they desire-quite the opposite from the trend in North America.  They would say “use a low slope (approximately 5/12) and keep the snow on.”

In an effort to solve the problems associated with moving snow and ice, I have heeded the experience and resources of European construction industry and have implemented their ideas with great success.  Here are some of the key factors in their approach to keeping snow on the roof.

Germans in general are not concerned with snow loads because they design the structure to hold the live load.  Designers there want the architectural freedom to have access around the building.  They also plan to use the snow as an insulation blanket and design a cold roof system to stop ice dam concerns at the eave.  The slope that works best seems to be 5/12.  This allows the snow to stay on while venting the roof system.  They then have the option of putting dormers on the roof without damage to the valleys, penetrations, lower roofs, and property below due to sliding snow and ice.

snow retention

snow retention

To complete this roof system, snow stops (or snow brackets) are used to stop all snow movement.  In Europe the majority of roofs are tile.  Many of the tile manufacturers make field tiles with snow stops as part of the tile. (See tile photo.)  Through extensive testing, they have found the snow stop’s fail point.  Once they know this, they engineer charts which help the consultants calculate how many snow stops are needed from eave to ridge based on roof slope and snow and ice loads to effectively hold the snow and ice on the roof.  With this information, European designers create roofs that effectively hold the snow and ice in place, as well as preventing roof damage and breakage. (See German chart, page 25.)

snow retention, snow bracket

I have found that if you want to stop damage to the roof from snow and ice, you must stop movement.  Snow fences do not do this, but properly placed snow bracket do.  In my research, I have found different conditions which require snow fences and/or snow brackets.  Snow brackets stop the movement of the snow on the entire roof.  They are typically installed over the entire roof.  Snow fences are meant to stop top-layered snow from sliding off like and avalanche over doorways.  These snow fence brackets normally attach to the rafters on two-foot centers.  If the eave-to-ridge length is over 20 feed, European designers usually place another snow fence row mid-span.  Both snow retention items are sometime necessary.  But without designing the snow retention based on accurate testing, you could be wishing you had that steep slope and metal roof (which was always intended to shed snow).  It is critical that a designer specify enough snow retention devices based on the slope and snow load.

It makes sense when designing a metal roof to shed snow, not to keep it on.  With expansion and contraction of the metal, it is difficult to attach snow retention devices into the roof decking without causing a roof leak or slotting of the metal panel from the snow bracket fastener.  If you attach only to the metal, the metal sheets can be torn off because of the use of expanding sheet clip system and the weight of the snow being held on.

The following roof types are good for keeping snow on:

  1.  Tile
  2. Asphalt shingles
  3. Wood shakes
  4. Slate

number of snow brackets, snow retentionWhen using these types of roofs, it is I important to know which climate you are in (i.e., number of freeze-thaw cycle and altitude and how to control vapor drive and ice damming.  These factors will make a difference in the roof design.  A cold roof system which controls these factors is ideal roof system.  In the cold regions of Europe, the roofers have manuals with detailed specification, details, graphs, and charts which explain cold roof system and how to successfully install them.  This is one reason keeping the snow on the roof is such a widely accepted practice-the roof are planned for it and installed correctly.  In the U.S., there is a manual on roof applications in heavy snow areas prepared by the Western State Roofing Contractors Association (WSRCA) and the National Tile Roofing Manufacturers Association (NTRMA).  This manual promotes the cold roof system and snow retention.

  1. To reduce ice dams and icicles.
  2. To exhaust vapor from the building.
  3. To extend the life of the underlayment.
  4. To provide an insulation blanket on the roof.


I follow Austrian venting charts for duct work size from eave to ridge.  I also pay close attention to air intake and exhaust size because many screens reduce air flow by up to 70%.  Then I install snow brackets and snow fences on the roof per manufacturer’s engineering design from eave to ridge.  With this I had great success in Sun Peak, Canada; Grand Targhee, Wyoming; Bear Creek, Colorado; Sundance, Utah, and many more.

Note: this year a manual called Concrete and Clay Tile Roofing Design Criteria Manual for Cold and Snow Regions was commissioned by NTRMA and WSRCA.  The manual helps determine the climate type and explains what design factors are important in the given zone.  It also explains essentials such as ice damming, vapor drive, and ventilation for cold roofs and includes venting charts.  For further information, phone WSRCA at (650) 548-0112.


  • Anderson, Terry, and Gillan, Leland, Concrete Clay Tile Roof Design Criteria manual for Cold and Snow Regions, WSRCA & NTRMA, 1998.
  • Braas Tile Venting Manual
  • Bramac Brochure on Venting, March 1996
  • Redland Roof Tiles Limited, 1998
  • WSRCA/NTRMA Cold Roof Committee
  • Zander Tile Roof Installation Book

By: Terry Anderson

Published: Interface January 1999

Download (PDF, 674KB)

Power of Ice – Sliding Ice & Snow Causes Roof & Property Damage

snow and ice, snow retention

By: John Del Grosso

Published: Architectural West | March/April 2003

The power of snow is seldom apparent as each unique snowflake falls to the ground.  Yet, when snow accumulates on the roof, the damage that can be caused by sliding ice and snow is a major concern.  Tim Ryan, president of the Arrowhead Condominium Association, a Private Unit Development, and head of the property-management firm for the association has firsthand experience in dealing with sliding ice and snow.

Located in Big Sky, Montana, the Arrowhead Condominium Association consisted of 24 units with metal roofs and a 12:12 slope.  These homes are only 10’ to 15’ apart, and each is a ski-in/ski-out unit on a hillside.  During harsh winter weather, the snow, ice dams, and icicles were sliding off the units and damaging neighboring homes.  The front door of one unit even collapsed three different times.  The decks on the buildings had to be closed for the winter, since many rails and decks had been torn off.  On lower shed roofs, not only was the metal roofing torn and bent, but the ¾” plywood sheathing was crushed between the roof’s rafters.

On several occasions, Ryan had worked with the Association’s insurance company assessing the damage.  The insurance company said it would not renew its policy due to the continuing problems.  “Their concern of the ice and snow killing someone was too great,” noted Ryan, “We did not know how to eliminate these problems, so we called Locati Architectures of Bozeman, Montana. They referred us to Terry Anderson of Anderson Associates Consulting, Inc.”

Anderson, who is the co-author of The Cold Roof Manual, published by the Western State Contractors Association and the Roof Tile Institute (RTI), visited the project to review all the damage and concerns.  He concluded that the only way to solve the problem was to stop the movement of ice and snow.

“Anderson recommended an engineered snow-retention system,” Ryan continued. “He also recommended a good ventilation system that, once installed, would stop most of their ice dam and icicle problems.  He visited with the board and gave them several roof options.  After reviewing the choices, the Arrowhead Condominium Association chose concrete roof tiles.  The association felt the concrete tiles had the longest record of use in Europe using a cold-roof design.  They also liked the look of the tile.”

snow and ice, snow retention

After Anderson Associates wrote the specifications and details, the project was bid out to qualified roofing companies who were familiar with the specified cold-roof system.  Trojan Roofing, from Salt Lake city, Utah, was selected.  The choice of all parties was concrete tile produced by Westile, Inc. of Denver, Colorado.

Since ground snow loads increased after the units were built, Anderson Associates hired a local engineering firm to check the structural integrity of the building for retaining snow and ice on the roof.  Securing the rafters properly to the plate-lien and purlins was the only minor change that was required.

Because it was late in the year and winter was approaching, the Arrowhead Association chose 14 of the 24 united to be reroofed immediately.  It was difficult for Trojan Roofing to work in the cold and snow conditions, but it gave all involved a great opportunity to see the difference between the old and new systems.

Many of the homeowners were concerned that the building could not retain snow on a 12:12 slope.  Anderson worked with the homeowners, assuring them that with proper engineering of snow fences and snow brackets, the roof system would retain the snow and ice on the roof.  The system was designed using a fully engineered snow-retention system with TRA Snow Brackets.

“Neither the homeowners nor the association understood what a cold-roof system was and how it would stop ice dams and icicles” stated Anderson.  “We worked very closely with them, explaining that venting air below the roof tile and above the sheathing would make melting and freezing equal from eave to ridge.  We used the RTI and WSRCA Cold Roof Manual and air ventilation charts from Europe.”

Since adequate ventilation was critical to the success of the roof system, Anderson calculated the air-duct size needed from eave to ridge.  He then designed an air-intake system from the eave and a ridge exhaust system in a raised-ridge vent.  Everyone involved was pleased to see the major difference from the old to new system, which was immediately apparent when icicles were eliminated and snow was retained on the roof.

snow retention

Homeowners of the first reroofed units were very pleased with the results.  The owners commented on how exceptional the tile looked with all the copper flashing and the copper TRA Snow Brackets.  The real proof of the improvements between the two roof systems became clear as the snow began to fall; the difference in the two roof systems was obvious.  The newly designed cold-roof system allows the snow to compact naturally with ice in the bottom 3”.  This ice freezes around the triangular portion of the TRA Snow Bracket.  This permits the natural run-off of water to shed between the ice and the roof tile when the outside temperature was above freezing.  Photos were taken to show the other property owners, who are all over the U.S., the improvements.

“The new units have stopped all snow and ice movement as well as icicles,” stated Ryan.  “The old units still have leaks, icicles, ice dams, damaged decks and snow and ice hazards.  Our association and homeowners are very happy with the look and design of the units.  We are looking forward to having the last ten units completed this spring and summer.  Retaining the snow on the roof has also reduced the heavy snow-removal cost.”

According to Ryan, “Credit needs to go to Anderson Associates Consulting, Western State Roofing Contractors Association and the Roof Tile Institute for the work on the Cold Roof Manual that made this system possible as well as the great work done by Trojan roofing while working in such bad winter snow and ice conditions.  The units look beautiful; they are safe and insurable,” concluded Ryan.

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Did Sliding Snow and Ice Damage Your Roof?

As the snow melts off of your roof, it can be nerve wracking to make the first trip up to the top of your house to assess the damage. With snow and ice sliding on and pulling at your roof all winter, there aren’t many homes that make it into the spring time unscathed.

Throughout the winter time you may notice large icicles forming at the edge of your roof or you may even see sheets of snow hanging off of your roof. The pressure that this snow and ice puts on your roof throughout the winter time can be extremely damaging. This spring, take the time to install a system on your roof that will prevent you from making repairs every spring.

damaged-roof-300x200Sound too good to be true? Stick with us! With a few tweaks and changes you can have a roof that is able to hold on to the snow throughout the winter. That’s right, hold on to the snow. If the snow stays on your roof, rather than melting, sliding, re-freezing and breaking it will simply act as an insulating layer for your roof. This insulating layer on your roof will slowly melt away without causing damage as it melts.

Let us help you keep make the necessary changes to your roof to ensure that snow sticks around throughout the winter and melts off naturally. With the right ventilation system, the right tiles and the right brackets we can be sure that you never have to make that scary trip up to your roof to assess winter damage again!