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Selecting Roofing Materials for Your Garage Roof

By Annie Crawford

September 14, 2023

A large vintage retro detached two car cape cod blue style garage, with grey shingled roof, windows,

Looking for the best roofing materials for your outdoor office, shed, or garage roof? It's not just about curb appeal—although looks are important.

Learning about the materials to consider for your roof pitch can help you reduce the risk of roof leaks. You can also benefit by knowing when you need roof ventilation or drip edging, when to consider insulation, and how to calculate roof materials costs. Here are the key details to understand.

The Importance of Aesthetics

Visual consistency is crucial when it comes to curb appeal. You want garage roof materials that flow with your home's architectural style, building materials, and color palette. For example, if you have an ornate Tudor-style home with wood-look architectural asphalt shingles, choosing a green metal roof for your garage could be visually jarring.

When it comes to winning home aesthetics, consider:

Accounting for Roof Slope

How steep or flat is your roof? Knowing can save you time and money because different roof slopes call for different roofing materials. To calculate your garage roof slope, determine how many inches your roof rises vertically for every 12 inches it extends horizontally. For example, if your roof's vertical rise is 6 inches, your roof pitch is 6:12.

Materials for High-Pitch Roofs

Generally, any roof pitch over 3:12 is considered a high-pitch or steep-slope roof. Steeper pitches tend to allow water, snow, and debris to slough off more easily than lower-slope roofs. Here are some materials the International Building Code (IBC) approves for high-pitch roofs:

Metal Roof Panels or Shingles

Typically having high fire-resistance ratings and offered in a range of colors, metal roofs are sleek and simple. They can be made from galvanized steel, aluminum, copper, zinc, and stainless steel. This material is long-lasting but is high cost.

Clay or Concrete Tiles

These tiles are commonly associated with Mediterranean or Southwestern-style architecture. Tiles provide great wind, impact, and high fire resistance ratings but are a pricier option. You also need to verify your structure can support this material's weight.

Wood Shingles

Wood shingles are aesthetically pleasing—and often seen in New England-style and Shingle Style homes—but may have lower fire resistance ratings than other options. An alternative to wood shingles are asphalt shingles with a wood shake-look, like GAF Timberline® NS Shingles.

Slate Shingles

Often seen on Northeastern homes and in high-end modern design, slate shingles can provide high fire resistance ratings, durability, and offer good insulation. But slate roofs are heavy and have a high cost.

Asphalt Shingles

Versatile, affordable, and attractive, asphalt shingles are the most popular roofing material in the US. Offered in a range of prices, styles, and roof shingle colors, asphalt shingles provide high fire resistance ratings and are reliable as well as low maintenance. It's important to note that the IBC has special underlayment requirements for roof pitches of 3:12 or less.

Always read the material manufacturer's requirements and adhere to installation instructions. Additionally, always check local building codes before selecting your roof materials.

Materials for Low-Slope and Flat Roofs

Flat and low-slope roofs can range in pitch from ¼:12 to 3:12. Flat roofs aren't completely flat because some slope is required for water runoff. Roofs with lower slopes can be more prone to water and moisture pooling than steep-slope roofs, so adhere to installation requirements to help prevent leaks. IBC-approved materials for lower-slope roofs include:

Self-Adhesive Membranes

A streamlined and versatile option, these watertight roof covers help protect against the inevitable water pooling that occurs on lower-slope roofs. Options like the GAF LIBERTY™ SBS Self-Adhering Roofing System offer attractive and durable protection. For example, the granule-surfaced GAF LIBERTY™ System has a quick and clean installation process, and comes in seven colors that complement GAF shingle colors.

Asphalt Shingles

The IBC approves the use of asphalt shingles on roofs with a pitch under 2:12, but a special underlayment installation is required to meet the IBC code. Work with local building codes, manufacturer requirements, and professional guidance to ensure proper use and installation of shingles on lower-slope roofs.

Roll Roofing

A good option for smaller residential roof projects, quick-install products like GAF Mineral Guard Residential Roll Roofing (for pitches 2:12 or lesser) provide roof protection and convenience.

How Roof Ventilation Helps Protect Your Investment

Proper roof ventilation can help protect your garage or shed interior by allowing damaging heat and moisture to escape. Check out the most common attic ventilation solutions by roof style.

Use the handy GAF Attic Ventilation Calculator to get started.

Why Climate Matters for Your Roofing Materials

Consider your regional climate before selecting roofing materials. Keep in mind average temperatures, average rain and snowfall, average wind speeds throughout the year, amount of sunshine, and frequency and type of natural disasters like hurricanes.

For example, in high-wind and storm regions, a durable asphalt shingle like Timberline HDZ® (eligible for a 15-year WindProven Limited Wind Warranty** with no maximum wind speed limitation when installed with required combination of four qualifying GAF accesssories—or up to 110 mph wind coverage without special installation) is a solid choice.

The Role of Drip Edge

Roofing materials like drip edge and flashing help prolong the life of your building. Without drip edge, your garage roof is more prone to water damage, pest infestations, and ice dams. Roof flashing keeps water from sneaking into roof joints if you have a larger project. Remember these important elements when selecting your garage roof shingles.

When to Install Insulation

Roof insulation could save you money on energy bills* if you'll be heating or cooling your garage or shed. Plus, insulation helps keep internal temperatures comfortable, which is important if you're using the building as a workspace.

The Cost of Roof Garage Materials

Roof materials are typically priced by the square. In roofing, one square equals 10 by 10 feet, or 100 square feet. Learn how to measure a roofing square to help determine your project size and cost. Keep in mind that a roof for a smaller building roof will be less expensive than the average cost of a new roof for your whole home.

Follow these steps to help estimate cost:

  • Identify the best materials for your project based on the roof slope, aesthetics, etc.
  • Determine the amount and different types of materials you'll need based on your roof size. Don't forget ventilation products if needed!
  • Decide if you'll need professional help to safely and properly install your roof; if so, account for area labor costs.

Ready to get started on your new garage or shed roof today? Get reliable help from a GAF-Certified Roofing Contractor.

*Energy cost savings are not guaranteed.
**15-year WindProven™ limited wind warranty covers GAF Shingles with LayerLock® Technology only and requires the use of GAF Starter Strips, Roof Deck Protection, Ridge Cap Shingles, and Leak Barrier or Attic Ventilation. See GAF Roofing System Limited Warranty for complete coverage and restrictions. Visit gaf.com/LRS for qualifying GAF products. For installations not eligible for the WindProven Limited Wind Warranty, see GAF Shingle & Accessory Limited Warranty for complete coverage and restrictions.

About the Author

Annie Crawford is a freelance writer in Oakland, CA, covering travel, style, and home improvement. Find more of her work at annielcrawford.com.

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When communities come together, incredible things happen. That's exactly the case in the city of Seattle, Washington, where the GAF Community Contractor Program has made lasting impacts on those in need through partnerships with Habitat for Humanity and ReBuilding Together. Both nonprofit organizations focus on working with homeowners to build new homes and revitalize communities in need of rebuilding, respectively.GAF's partnership with Habitat for Humanity began in 2011. From the start, it felt like a natural pairing. 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This ideal extends to the GAF Community Contractor Program, where GAF certified contractors can partner with GAF and give back through the following initiatives:GAF Habitat for Humanity Program. With over 1,500 local Habitat for Humanity affiliates in the U.S., GAF-certified contractors can partner with their local chapter to provide the labor to install fully-donated GAF roofing systems. Volunteers don't work alone. Homeowners invest hundreds of hours of their own labor into building their Habitat house.GAF Affordable Housing Reroof Program. This initiative encourages contractors to partner with any 501c3 nonprofit organization in their community for a reroof project, for which GAF will donate the shingles.GAF Roofs for Heroes. GAF-certified contractors can partner with a local 501c3 to perform roof repairs or replacements for local heroes. These heroes include healthcare workers, first responders, veterans, police, fire, and EMTs.As part of the Community Contractor Program's progress in Washington state, more than 20 GAF certified contractors were able to provide over 100 new roofs to those in need of a new roof in the Seattle region, working with Habitat for Humanity and ReBuilding Together. "Giving back is at the core of what GAF does, but bringing in and partnering with our contractors is something that makes us unique," explains GAF Director of Corporate Social Responsibility Arlene Marks.Celebrating Giving Back While Giving Back AgainMarks and Gladstone wanted to host an event to thank the contractors who donated their time and labor to install those roofs and came up with a unique and fun way to extend the spirit of giving through Welcome Home Toolkits. "This was Arlene's idea, and it was such a great one," Gladstone notes.Marks shares, "We try to make all of our events meaningful, so what was the best way that we could reach back out to these homeowners that we've already helped? The Welcome Home Kits were the answer."The contractors attending the event assembled toolkits containing basic items like screwdrivers, nut drivers, adjustable wrenches, pliers, hammers, safety glasses, and more. The kits also include a video message of encouragement from the program participants.Most of the individuals who are helped through the roof donations are first-time homeowners. Accordingly, many don't have the basic tools needed to maintain their homes. 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It was an opportunity to work together toward a common goal to meet, share ideas, and talk about the market in a very safe and non-competitive environment."Impacting the CommunityA representative from Habitat for Humanity attended the appreciation event in Seattle to say thank you and share how much of an impact ReBuilding Together and the contractors' work have had on the community. The Welcome Home Toolkits were provided to both organizations and have gone a long way toward welcoming and inspiring the new homeowners.Looking to get involved in giving back to your community? Visit the GAF Community Matters page to explore different opportunities and get started.

By Authors Karen L Edwards

March 01, 2024

Cold storage facility for fresh produce
Building Science

Is your Cold Storage energy use through the roof?

This piece is co-written by Jennifer Keegan, AAIA. The headaches of Cold Storage facility operations extend beyond making sure the ice cream doesn't melt. Owners and Operators are regularly challenged with: Selecting a cost-effective roof system that is going to be long-lasting Working around unsafe areas in the interior due to ice accumulation Struggling to reduce monthly energy bills For Owners who are looking to increase energy savings and safety records, your roof not only keeps the weather out, but can help resolve these operational issues. _____________ Cold Storage buildings are designed to maintain cold temperatures, much colder temperatures than a typical building. Cold storage facilities, such as blast freezers, may be required to maintain an interior temperature of minus 50 degrees Fahrenheit. Having a structure that is properly insulated and sealed to maintain the required temperature and minimize ice build-up is important not only for the products being stored inside, but also for potential energy savings over the life of the facility. How can roofing materials impact energy savings? Think of the walls of the Cold Storage facility as a jacket, and the roof as a hat. When it is cold outside, you want to make sure that you have a jacket and a hat to insulate and keep you warm. The same idea applies to a Cold Storage facility — the roof and walls of the structure insulate the products inside. But in this case, when it's warm outside, they keep the products inside cold. Not having enough insulation, on either the walls or the roof, will make your mechanical systems work harder to maintain the interior temperatures, which increases energy use, and can result in higher energy bills. The effectiveness of roof insulation is determined by its R-value. According to Energy Star, R-value is a measure of an insulation's ability to resist heat traveling through it. The higher the R-value, the better the thermal performance of the insulation and its effectiveness at maintaining interior temperatures. R-value is typically expressed as a value per inch of insulation, and the recommended R-value of Cold Storage spaces will vary based on the interior temperature, although they are much higher than typically recommended for a traditional building. For comparison, a traditional office building may require an R-value of 30. In the 2018 edition of the American Society of Heating, Refrigeration and Air Conditioning Engineers' ASHRAE Handbook – Refrigeration, there are suggested minimum R-values for Roof Insulation between 30 and 60, depending on the cold storage type. R-values will vary by product, including factors such as thickness and density. 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Similarly, for a Cold Storage building, it is beneficial to select a lighter-colored roof in order to reflect the heat from the sun to assist in reducing the already high costs related to cooling the building. Reflecting heat from the sun will decrease the heat radiating into the interior, which means the cooling equipment will not have to work as hard to maintain interior temperatures, and will ultimately work more efficiently. What about roof attachment? We discussed the concept of thermal bridging and how energy loss occurs at discontinuities between the joints of the insulation, but thermal bridging can also occur where there are fastener penetrations through the roof system, as seen in Figure 1. Fasteners are used to attach the insulation and the membrane to the roof deck, which is referred to as a mechanically attached system. 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Similar to the loss of energy created by thermal bridging, air flow through the roof created by poor detailing results in considerable loss of the cooled temperatures required in the space below. Additionally, air flow that condenses can collect within the roof assembly, including within the insulation, and freeze. Frozen insulation is a common side effect of a Cold Storage roof that is not functioning properly. Frozen insulation is exactly what it sounds like — insulation that has had moisture accumulate within it and then freezes. Frozen insulation has properties similar to wet insulation and is ineffective, since it provides virtually no insulating properties. A frozen roof is almost like having no insulation at all, and the energy used to maintain the interior temperatures goes through the roof! Proper detailing of a Cold Storage facility begins during the planning stage. Determining the type of interior spaces, the sizes, and the overall usage of the facility should be taken into consideration. Once the overall layout of the Cold Storage facility is decided, the construction materials, including the roof assembly, will need to be determined. Once the roof assembly is selected, design of the roof details is crucial. Typical details, including roof-to-wall interface and penetrations, must be meticulously thought out and designed. Roof-to-wall interfaces and penetrations must be sealed to prevent air from entering into the roof assembly. Even the smallest gap that allows air flow can have detrimental effects on the roof assembly. The most common method of ensuring sealed terminations and penetrations is the use of a closed-cell spray foam. Closed-cell spray foam is typically installed at the intersection of the exterior walls and the roof insulation at a width of one inch and extends from the deck level to the top of the insulation. At wall-to-steel deck intersections, it is also best practice to install spray foam in the deck flutes a minimum of 12 inches from the wall. The closed cell spray foam helps to seal the interface so air cannot enter into the roof assembly. Figure 4: GAF Detail 201C Coated Metal Roof Edge at Insulated Wall Panel Proper execution of the roof installation is critical and requires a contractor with Cold Storage construction experience. Having the right partner who understands the importance of their role in the project and collaborates with the team can make or break the project. A future article will dive into these details. In the meantime, for information on GAF-certified contractors, talk to GAF first. The benefits outweigh the risks. Seemingly insignificant decisions made during the design and construction of the roof of a Cold Storage facility can impact the functionality and energy usage of the building for the lifetime of the roof system, which is typically 25-35 years. Once air leakage occurs into a roof assembly, the damage that occurs is often irreversible. Ice accumulation on the floor can be a serious hazard for occupants and workers. The challenge of identifying where the breaches in the roof assembly occur, let alone remediation, can be difficult and costly. Remediation of the identified problems generally includes removal of frozen insulation as well as addressing the identified problem areas which are often attributed to detailing and air leakage. The associated consequence of a poorly designed and installed roof is the cost of the energy loss. Mechanical equipment having to work harder to maintain temperatures will result in higher costs due to an increase in energy use, and the effect of the equipment working harder often leads to premature mechanical failures. The benefits associated with designing and installing a proper Cold Storage roof far outweigh the risks. A properly designed and constructed roof will save energy, prolong the life of mechanical equipment, and protect both the building's occupants and the goods being stored inside the facility. Need to talk to an expert regarding Cold Storage roof design? Talk to GAF first. Email us at coldstorage.assistance@gaf.com for design questions, detailing assistance, and expert advice.

By Authors Kristin Westover

January 26, 2024

A roofer unloads shingles on to the roof of a house prior to installing them
Your Home

How to Find a Roofer You Can Trust

Whether it's time for a new roof or a repair, you'll need a roofing contractor to help you make the right choices for your home. But if you haven't hired a roofer before, you may not know what to look for.From referrals and licenses to manufacturer certifications, here's how to find a roofer you can trust with your home.Ask for Recommendations or ReferralsOne of the best ways to find a roofer is to ask people you trust for recommendations. If you have a friend, relative, or neighbor who has had their roof repaired or replaced in the last few years, ask them who they used.Many communities and neighborhoods also have local Facebook groups or message boards. You can use these resources to get recommendations for experienced local contractors—and find out what roofing companies you should avoid.Look for Manufacturer CertificationsSome roofers become certified by one or more roofing manufacturers.If a contractor is part of a manufacturer's certification program, the contractor is more likely to be familiar with the manufacturer's products and may be eligible to offer enhanced warranties. Each program has it's own requirements so you should check the manufacturer's website to see what a particular certification entails.For instance, GAF Master Elite® contractors must be insured and licensed in states where they operate (if required). GAF also considers factors such as years of roofing experience, credit rating and overall standing with the Better Business Bureau. GAF Master Elite® contractors are the only roofing contractors who can offer the GAF Golden Pledge® Limited Warranty* with up to 30 years of workmanship coverage on qualifying roofing systems.In addition to certification programs, manufacturers may recognize certain contractors with awards. For example, GAF Master Elite® President's Club award-winning contractors demonstrate continued excellence in three key areas: performance, reliability, and service. Over the course of the prior year, award winners must have installed a minimum number of roofing systems that qualify for the highest warranties.Review the Contractor's Online ReputationWhether you first connect with a contractor through a recommendation or a quick Google search, do some online research to ensure you find a roofer you can trust.Read company reviews, see what customers say on the contractor's social media pages, and visit the contractor's website for details on their products, services, and experience. You're looking for a company with a good track record and reputation. Once you've gathered all this information, you'll be able to make a more educated decision.Check the Contractor's License and InsuranceYou want to work with a licensed contractor (in states where licensing is required). If your state requires roofers to be licensed, run a license check on your state's Department of Consumer Affairs or business licensing website.Also, make sure the contractor is insured with coverage for all their employees and subcontractors. This will help protect you if a worker injures themselves on your property or damages your home while working.Visit the Better Business BureauThe Better Business Bureau (BBB) has a database of information about businesses in different industries across the country. You can search by business name or business category (i.e., roofing), and then enter the name of your town or zip code to find companies that have BBB accreditation or a high rating. Some listings also feature customer reviews, which is another way to determine whether you want to work with a particular roofer.Choosing the Right Roofing Contractor for Your HomeWhen you find a roofer you can trust to work on your home, price shouldn't be your only consideration. Experience, quality of service, and reputation also matter.Take the time to research potential roofers. Ask for recommendations, look for contractors with manufacturer certifications, and check your state's contractor registration or licensing site and the BBB website. Following all these steps can help you pick the right roofing company for your job.Once you've selected a contractor, it's time to get ready for your roofing project to begin. Check out this checklist for your next roofing project for next steps.*Contractors enrolled in GAF certification programs are not employees or agents of GAF, and GAF does not control or otherwise supervise these independent businesses. Contractors may receive benefits, such as loyalty rewards points and discounts on marketing tools from GAF for participating in the program and offering GAF enhanced warranties, which require the use of a minimum amount of GAF products. Your dealings with a Contractor, and any services they provide to you, are subject to the Contractor Terms of Use. Visit www.gaf.com/gaf-contractor-terms-of-use for details**Eligibility requirements, coverage, terms and restrictions apply and vary based on the enhanced warranty and products installed. For details and to view fullGolden Pledge Limited Warranty visit https://www.gaf.com/en-us/for-homeowners/warranties. Visit gaf.com/LRS for qualifying GAF products.

By Authors Dawn Killough

January 25, 2024

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