Upgrading Your Roof with Metal Panels

In a recent blog post, we reviewed key considerations to help a building owner decide whether to repair or replace a damaged roof. In this post, we’ll address some ways metal roofing systems are an advantage when upgrading your roof and restoring your building to “like-new”, weathertight condition.

MBCI Blog: Upgrading Your Roof with Metal Panels

Installing Metal Panels Over Existing Roofing

Some owners are concerned about replacing a roof because they dread the cost of removing the existing roof. This concern is valid in many low-slope roofing situations because the new roofing membrane might not be compatible with the existing one, and could cause premature deterioration. There are, however, metal panels specifically designed to be installed directly over existing roofing. And, many of these retrofit systems can be installed over existing roofs made of metal or other materials. Avoiding removal of the old roof obviously saves on cost. However, it also saves considerable time when installing the new roof. As an exposed-fastener metal roofing system, this retrofit application also requires fewer construction components, further streamlining the installation process.

Retrofit metal panels typically feature a membrane treatment that prevents rust or contaminants from the old building materials from transferring to the new panels. This is a versatile solution for both low- and steep-slope roofs (minimum slope: ½:12). It is also very durable and can feature approvals for use in extreme weather locations, including Florida. Metal panels are available in a variety of colors that enhance the overall design of a building. Often, this “replacement metal over existing roofing” approach is the most cost-effective, even compared to some repairs. Additionally, new roofing is more likely be eligible for a warranty, while repairs rarely, if ever, are.

Upgrading Your Roof with Insulated Metal Panels

Energy conservation is on the mind of many building owners and building code enforcement officals. Therefore, adding insulation when upgrading your roof is often required to adhere to building codes. In this case, applying zee-shaped sub-purlins over the existing roof system helps support a new layer of metal roofing. In between the sub-purlins, insulation can be added to meet or exceed current energy code requirements. This system also eliminates the need to remove the existing roofing while providing an added layer (or more) of insulation to improve the overall energy performance of the building. Insulated metal panels (IMPs) like MBCI’s can help keep buildings cooler in summer and warmer in winter—conserving energy year-round.

Sub-purlin systems can fit any existing metal panel, support new panels, and be made to accommodate many types of insulation between the old and new roofs. They can also  support or incorporate a variety of solar energy systems where desired. Roof panel options include variety of profile shapes, textures and colors to suit aesthetic preferences.

Altering the Roof Slope

In some cases, upgrading your roof means changing the roof slope (i.e., turning a low-slope roof into a steeper-sloped roof). In these cases, metal roofing systems can be the most economical choice. Steel framing (16-ga. to 12-ga.) installed over the existing roof frame creates a sloped plane that can support new metal roofing panels. Note that the existing physical shape of the roof, the existing structural system and other rooftop conditions are usually the biggest factors in the geometry and shape of the new roof. Nonetheless, the beauty of the system is that it can dramatically improve the appearance and drainage of a building’s roof, regardless of whether the substrate is steel, wood or concrete.

Lower-slope applications (1/2: to 2:12) are typically driven by economy and designed to efficiently discharge rainwater from the roof. Higher-slope applications (greater than 2:12) often serve to improve and update the look of an existing building. They achieve this by showcasing the metal roof while also improving its drainage and durability. Once the framing is installed, standing-seam metal panels can be installed over the top, creating a ventilated attic space. This allows space for additional insulation , thus improving the energy performance of the building.

Working with Building Professionals

Any of these options are applicable over an existing metal roofing system. They cab also convert other types of roofing systems to longer-lasting metal roofing, or replace an existing roofing system altogether. Of course, engaging the services of a design professional (architect, engineer, etc.) is always appropriate when considering your options. They can help properly assess existing building conditions and recommend the best overall metal roofing solution from metal panel manufacturers.

To learn more about upgrading your roof system with more durable, longer-lasting, better-draining and easier-to-maintain metal roofing systems, contact your local MBCI representative.

Should You Repair or Replace a Roof? How to Decide

Roofs on buildings of all types are prone to damage, wear, deterioration, or leaks. When this happens, it leaves the owner wondering whether to address the problem through repair or replace the entire roof. How to decide? There are a number of key considerations:

MBCI Blog: Repair or Replace Your Roof?

What is the existing roof type?

Different roofing materials require different construction methods, and range in suitability for various types of building conditions. Low-slope roofs commonly feature either asphalt/bituminous roofing, polymer-based membranes or metal roofing. Each of these roofing types has its own procedures, materials and costs associated with identifying and repairing a leak. Steeper-sloped roofs can feature asphalt shingles or metal roof panels. These have various life-span expectations (metal lasts much longer, for example) and different ways to identify issues. Understanding the existing roofing type is fundamental in deciding on the best course of action.

Is the roof under warranty?

Regardless of the roofing type, there may be a warranty in effect that requires any inspection and repair work to be performed by someone certified or approved by the roofing manufacturer. Otherwise, undertaking an independent repair may render the warranty null and void. Hence, before anyone does any work on the roof, contact the manufacturer and confirm the applicability (or not) of a warranty. At this time, you can also evaluate any other options or conditions for a repair. The advantage of a warranty is that there should be little, if any, cost to the owner to repair the roof as long as the work is done according to the warranty terms. Without a warranty in effect, it’s entirely up to the owner to decide whether to repair or replace the roof.

How old is the roofing?

If the current owner is the original owner of the building, the roof age should be easy to determine. But what if this is a pre-owned building? It is often beneficial to determine how old the roofing is so you can understand any potential service-life trade-off. This will play directly into the cost-efficiency of a repair versus a replacement. If the roof is near the end of its service life, then a repair might not make sense if a full replacement is imminent anyway. If the roof is fairly new, then the question of how long a repair may last is important. Will it need to be repeated again before the roof is ready for replacement, and if so, at what cost?

Where is the actual location of the damage?

Is it really the roofing that’s a problem? Could it be something related—such as edge flashing or seals around a roof penetration (i.e. a chimney, pipe, or rooftop equipment connection)? If the damage is in isolated areas, a simple repair or flashing replacement may be the easiest solution. If the condition is more widespread, however, then a replacement may be more logical to address the larger area(s) affected.

 Is this building in a high-risk area for more damage?

Buildings prone to high winds or other severe weather need a more durable roofing system than areas where the weather is less dramatic. If the building is in a high-risk area, it might be reasonable to avoid relying on repairs and instead go for a full replacement.

Are there other inherent issues?

Sometimes, the roof covering isn’t the root of the problem. For example, Low-slope roofs often experience “ponding,” where water can sit in a slightly depressed or settled section of the roof. This can lead to deterioration and leakage over time which is not the fault of the roofing, but of the structure or insulation beneath it.

Similarly, steeper-slope roofs may be designed with a geometry or penetrations that prevent proper drainage and cause issues due to water backups. Or, perhaps ice build-up in winter is causing problems with the insulation in the roof system. Identifying the proper issue that is causing the problem will allow for selecting the best solution.

Deciding to repair or replace

Answering the basic questions above will likely reveal which approach—repair or replace—is most appropriate. Small areas of damage in areas in low-risk locations may best be served by simple repairs. If there are many years of roof life remaining or a warranty is in effect, this is especially true. However, missing or faulty components, worn or brittle membranes, or rusting metal panels may all be indications to replace the roofing entirely. This is even more important if the roof is quite old, out of warranty, or in a high-risk area.

In our next post, we’ll look at how metal roof systems help solve a variety of problems within different budgets. In the meantime, contact your local MBCI representative to learn more about roofing warranties and roofing systems for buildings.

Why Choose Retro-R® Panels?

If you are looking for a low-cost retrofit solution and want to cover your roof with a lightweight, through-fastened panel, MBCI’s Retro-R® Panel installed over your existing roof could be the answer. Retro-R® panels provide a host of advantages for the retrofit roof project, including allowing the existing roof to stay in place during installation, thereby eliminating business downtime; time and labor cost savings; minimizing the possibility for water entry into the building; and providing a safer working environment—all with energy-efficient, versatile options. Here’s a quick rundown of some specific benefits of Retro-R® panels.

MBCI's Retro-R® panel can be installed directly over an exiting R panel.
MBCI’s Retro-R® panel can be installed directly over an exiting R panel.

Cost and Time Savings

There are a number of potential cost saving scenarios afforded by choosing the Retro-R® panel solution. First and foremost, this panel entirely eliminates the roof or wall removal process as it is installed directly over an existing R panel. This allows the facility to remain open so there’s no interruption to business operations, minimizing the loss of revenue.

Also, by not having to remove the roof or wall, installers save time (which also equates to lower labor costs). Not only does installation of Retro-R® panels save time in the project schedule and maintaining operations, this exposed fastening system requires fewer installation accessories, thereby keeping costs down while still providing a new look and long product life.

Additionally, existing rooftop equipment, vents or light transmitting panels can all be accommodated by the Retro-R® system, again providing significant cost savings when compared to installing a new roof system.

Installers may also be able to reuse all the trim from the original building when utilizing Retro-R® panels for a retrofit. They may not have to remove certain roof elements, such as the rake, gutter or down spouts; in fact, they may not even have to disassemble them. On one recent Retro-R® retrofit project, for example, Texas-based Benny’s Transmission, installers only took the ridge vents up in order to lay the panels flush, and were able to reuse them once the roof was installed, adding up to large material and labor savings for the building owner.

With a seamless solution to their 41-year-old roof in mind, Benny's Transmission selected MBCI's Retro-R® panel to be installed over their existing roof.
With a seamless solution to their 41-year-old roof in mind, Benny’s Transmission selected MBCI’s Retro-R® panel to be installed over their existing roof.

Site Safety

Any time installation time and required manpower are reduced, jobsite risks are also reduced. Additionally, it is more likely an installer could fall through if the original roof is not in place. With Retro-R® panels, if tied off at the eave, that risk is minimized as well. Generally speaking, inspecting and evaluating the existing roof panel and structure to determine if they will support the new panels and any live loads on the roof during installation is a key safety guideline.

Long Lifespan and Rust Prevention

The Retro-R® panel has a Drip Stop membrane to prevent rust from the old roof or wall from transferring to the new panel, which helps contribute to a longer lifespan.

Coatings, Color Choices, and Energy Efficiency

With availability in both 26- and 29-gauge Galvalume Plus® and Signature 200 color options, MBCI’s Retro-R® roofing system is a great option for retrofitting projects. On the Benny’s Transmission project, for example, the color chosen was Galvalume Plus®, which comes with a 20-year Galvalume warranty through MBCI. Although there was no extra insulation added, the high reflectivity of the Galvalume roof increased the building’s energy efficiency.

All in all, Retro-R® panel systems can be a cost-saving, efficient, versatile solution for your next retrofit project.

To find out more about Retro-R® panelscontact your local MBCI representative or stop by MBCI’s booth #2245 at the International Roofing Expo 2019 in February to see this panel installed live. Can’t make it to IRE? Tune in to our Facebook page on Tuesday, February 12th to watch our demos live!

Why Upgrade a Roof to Metal Panels?

Have you considered using metal panels in building and roofing upgrades? Metal roofing panels from MBCI offer significant advantages over traditional roofing material, including the ability to be integrated with the existing structural system. For buildings that need to comply with strict code requirements, our huge selection of metal roofing can meet your needs.

Save Money with Metal Roofing

Using metal instead of asphalt shingles for roofing provides several cost-saving benefits, including:

  • 60-year lifespan: The strength and durability of metal is unparalleled compared to traditional asphalt shingles, and weathers the elements for a much longer period of time.
  • Sustainability: Our cool roof coatings are extremely energy-efficient, saving you cost associated with heating and cooling your building. With strict requirements in place for buildings today, reducing energy and maintenance costs is top-of-mind, and metal roofing is a simple solution that offers both. MBCI also works with LEED project documentation and has EPDs using LCA results for core panels.
  • Higher Quality Material: From insulated to standing seam and exposed fastening roof panels, our selection of panels are available in gauges ranging from 22 to 29, with a variety of finishes and coatings to ensure your metal roof stands the test of time.
  • Extensive Warranties: MBCI’s signature panels each come with their own unique warranty, with coverage for features including film integrity, chalk and fade, and more depending on the product.

It is important to note that when working with older buildings, there is a possibility of degradation of the subsurface as well as pre-existing structural issues such as overloading the structure.

MBCI's metal roofing panels are a durable and energy-efficient alternative to standard roofing products.
MBCI’s metal roofing panels are a durable and energy-efficient alternative to standard roofing products.

Panels & Systems for Every Application

  • Standing Seam Panels: Commonly used for a variety of commercial, residential, and recreational applications, these are some of the most durable and versatile systems available. We offer everything from mechanically field-seamed panels to curved and snap-together options. No matter what your building is used for, these systems withstand the elements and have fire and impact resistance ratings.
  • Lightweight Panels: MBCI’s product line features lightweight panels that can be used as framing and sheeting materials. For example, the BattenLok® HS is a high strength standing seam roof systems that can be installed directly over the purlins or bar joints. The type of metal paneling chosen for your roofing systems allows for additional customization by being able to choose your color with our extensive color chart. The experts at MBCI have years of experience matching the retrofit roof panels to the new roof membrane.
  • Exposed Fastening: With 9 different styles to choose from, MBCI’s vast selection of exposed fastener roof panels are sure to exceed your expectations. Cost-effective and easy to install, these panels are often used in commercial and agricultural buildings, and are designed for both vertical and horizontal installation.
  • Retrofit Systems: Selecting the correct roofing system is critical in the retrofitting process. MBCI’s NuRoof® retrofit system has the capability to “stick-frame” the current supporting structure. The new retrofit system allows for redistribution of loads while increasing the energy-efficiency of the building. If you prefer installing new panels over existing roofing, the Retro-R® Panel can enable you to skip the removal of the existing roof entirely. This is a great option for saving time and cost related to installation, and can keep your operation up and running with no downtime. The Retro-R® Panel’s Drip Stop membrane prevents rust from old roofs from interfering with new panels, providing a new look with a long life span. With availability in both 26 and 29 gauge Galvalume Plus® and 200 color options, the Retro-R® roofing system is a great option for retrofitting.

To find out more about which metal roofing panel is ideal for your new project or existing building, contact your local MBCI representative.

 

Five Retrofit Choices Using Metal Roofing Systems

Buildings usually need new or replacement roofing installed at some point during their service lives. New metal roofing is an ideal roofing retrofit option due to its longevity and durability, which can extend the life of the roofing and require fewer replacements over time. The aesthetic appearance of a new metal roof can also make a notable visual impact to upgrade the building itself.

When considering such a metal roof retrofit on an existing building, the first thing to realize is that there are a number of choices available. Here is a quick look at five of the most common ones that can be selected from and tailored to suit a particular building. Note that since all of them will add some structural loading to the roof, all the retrofit solutions should be reviewed by a professional structural engineer to be sure the existing building can accommodate the changes.

1. Double-Lok® Clip System

When an existing building has an existing PBR roof panel or similar, a Double-Lok® clip and panel system can be installed directly over the existing roof with minimal alterations. In this case, 2″ standoff clips are run from eave to ridge and fastened through the existing roofing panels down into the existing purlins. Then new standing seam metal roofing panels are installed along these clips so they are held 2″ above the purlins and 3/4″ above the major ribs of the existing panel roof. Because of these clearances, the cavity between the old and new roofs can either be vented or additional insulation can be added. Venting the cavity can be a good option when the existing roof slope is 3:12 or greater, as this allows for convective air flow during the summer and can help reduce the chance of ice damming in the winter. For any slopes of 1/2: 12 or greater, adding insulation can improve the overall thermal performance of the building. Generally, this system allows for considerable versatility, even if it takes more parts and labor than some other solutions.

2. Retrofit Roof Panels Over Existing

For cases where a standoff isn’t sought, new, non-structural metal roof panels with a specifically retrofit profile can be installed directly over existing roof panels on roof slopes of 1/2: 12 and greater. That means there is no need to tear out the old roof, since the new panels are through-fastened into the old ones and the purlins below, all in a pattern that avoids the original fasteners. Such retrofit panels are available in 29 and 26 gauge in full range of colors and come with a factory-applied vapor barrier on the underside. Even light-transmitting panels are available for this retrofit panel system.

Retrofit
5 most common choices for retrofit metal roofing systems

3. Notched Sub-Purlins

A variation on the metal-over-metal roofing approach is to use specifically designed z-purlins with notch-outs that are screwed down to the existing purlins. Unlike other systems that run retrofit support members from the eave to the ridge, the notched purlins run parallel to both (in line with existing purlins) with the notches spaced to clear the ribs or corrugations in the existing metal roofing. Profiles are available to match virtually any metal roof produced in the last 50 years. That means they can be installed over existing roofing and, in the process, provide enhanced structural capabilities because of the added sub-purlins.

4. Grid System

When an existing purlin spacing doesn’t meet current code requirements, then the use of crisscrossing hat sections in a grid pattern can provide the additional support needed. Such grid systems are designed to go directly over existing sloped roof systems but many require the use of specific metal roofing panels to work properly.

5. New Framed Roof System

In some cases, a full, steep-sloped roof (greater than 4:12) is sought to be installed over a low-slope roof (1/4:12 – 4:12). In this case, a full metal framing system is available that will create the desired roof slope and transfer the new roof weight to the existing roof deck above the existing roof structural members. As such, the coordination of the new system with the existing roofing, insulation and structure needs to be addressed by licensed engineers. Once designed and installed, an “attic space” will be created by the new retrofit roof system, which should include proper venting in accordance with applicable codes, allowing trapped moisture to escape. It is also recommended that such “attic space” be reviewed by other building, fire, or insurance-related officials for possible sprinkling or extension of existing fire walls to the bottom of the “new” roof system. Regardless, a minimum of 3″ vinyl-faced roll insulation between the retrofit panels and the retrofit purlins will help prevent condensation and roof noise in addition to improving energy efficiency.

To find out more about which retrofit options, or options, are best suited to a particular building that you are involved with, contact your local MBCI representative.

How to Retrofit Existing Roofs with New Metal Roofing Systems

In our prior blog post, Benefits of Roofing Retrofits with Metal Roofing Systems, we looked at the benefits associated with retrofitting an existing building with a new metal roofing system. In this discussion, we will look at several ways to do it.

New Sloped Roof Over an Existing Flat Roof

Buildings with flat roofs can be retrofitted with light-gauge steel framing systems to create a new sloped metal roof. Such systems can be installed directly over existing roofing membranes and structures, subject to appropriate structural engineering review. These systems typically use light-gauge (16 gauge to 12 gauge) steel framing installed directly above the existing roof to create a sloped plane. Regardless whether the existing roof structure is steel, wood or concrete, the new, lightweight framing system can be designed to disperse roof loading appropriately and connect securely.

The physical footprint of the existing roof, the type of framing system employed, and any special rooftop conditions will typically control the final geometry of the new sloped roof. A low-slope application (less than 2:12) can be selected based on economy and configured to discharge rainwater off of the roof. High-slope applications (greater than 2:12) are typically selected to improve and update the look of an existing building while improving long-term performance. Once the metal framing system is in place, then standing seam metal roof panels are commonly installed, creating a ventilated attic space in the process.

Retrofit Roofing Panels

Low-slope metal roofing can be a great choice when a fairly utilitarian solution is needed for improving overall roofing performance. Exposed fastener systems can be used to allow direct installation of the new roofing panels over existing metal roofing or some other materials. Roofing panels specifically designed for retrofit applications typically have a rib spacing of 12″ on center with a rib height of just over an inch. The minimum slope for such a panel is 1/2:12. Any existing lap screws must be removed from the existing roof before the new panels are installed. The new retrofit panels are then attached with screws that fasten through the existing panel major ribs and into the existing purlins.

A New Standing Seam Roof

In some cases, an existing sloped roof may have another roofing material in place that is nearing the end of its service life. In that case, a new long-lasting, standing seam metal roofing system can be installed directly over the existing roof. Some systems will require a simple sub-framing system that allows the new roof to be installed directly over the existing. Retrofit roofing systems such as this can be UL-90 rated and FM Global rated. Other strategies exist to increase the energy efficiency of the building when adding new standing seam roofing, such as adding unfaced fiberglass insulated between the existing and the new roof and to vent the cavity between the old and new roofs by adding vent strips at the eaves, plus a vented ridge to allow air intake and exhaust. This method works well with roof slopes of 3:12 or greater.

Retrofit
OST Trucking Co. featuring Retro-R® metal panels in Polar White.

End Results

Regardless of the specific system selected and designed, installing a retrofit metal roofing system allows the existing roof to remain in place, which saves on labor costs. It also minimizes the chance for water entry into the building during the roofing process and provides for a safer working environment. Existing rooftop equipment, vents, or light-transmitting panels can be accommodated by any of the systems described.

According to the Metal Construction Association (MCA), “retrofit metal roofing represents an economical and functional solution for building owners who want to beautify their existing structure or correct performance issues related to aging roofs and out-of-date materials. They have been employed in millions of square feet of existing commercial, industrial, retail and education facilities. The result is a new code-compliant metal roof that will last for 60-plus years, providing higher energy efficiency by reducing heat gain through the roof in summer months and reducing heat loss during winter months.”

To find out more about these retrofit systems, contact your local MBCI representative.

Benefits of Roofing Retrofits with Metal Roofing Systems

Many commercial buildings, and even some residential ones, have low slope or “flat” roofs that can be problematic to maintain. They typically rely on a membrane of some sort that in and of itself is waterproof, but every seam, penetration, flashing, and other detail is a potential leak if not installed and maintained properly. Further, the subsurface that the membrane sits on determines the actual slope to roof drains so if that is compromised, then standing water can sit on the roof and cause issues. Even the roof drains are a concern if they get clogged with debris or leaves and cause water to back up and stagnate on roofs.

Given the potential difficulties, and the frequency of replacement that is often needed for flat roofs (average of 20 years), it is no surprise that many facility managers or owners look to retrofit their buildings with sloped metal roofs wherever the size and geometry are conducive to it. In doing so they recognize the many benefits obtained which can include any or all of the following:

Reduced Maintenance with Metal Roofing

A complete metal roof system (e.g. metal framing, metal roofing, insulation, and ventilation) can be designed and installed to require minimal maintenance. That means not only fewer potential problems, but reduced operating costs over the course of many years.

Increased Roof Lifespan

Metal roofing is recognized by industry experts for having a very long lifespan even under challenging weather conditions. It is not uncommon for a metal roof system to last 60 or more years compared to a 20-year average for flat membrane roofs. If Galvalume® coated steel is used (i.e., zinc/aluminum coating licensed to roofing manufacturers), the roof lifespan can be expected to last the full service life of the building, according to studies done on standing seam roofs by the Zinc-Aluminum Coaters Association and the Metal Construction Association (MCA). Long-lasting roofing means there is only one installation to provide and pay for, not multiple ones over the life of the building.

Retrofit
Tum-A-Lum Lumber featuring Retro-R® Metal Panels

Improved Building Energy Efficiency

Retrofitting with new insulated metal roofing systems is an excellent solution to high energy consumption and associated costs in a building. Retrofit systems can be designed to work over existing flat roofs or even over older sloped metal roofs to upgrade a building to meet or exceed current energy code requirements. Such systems add insulation between the old and new roof reducing heat gain in summer and heat loss in winter. The metal roofing can also be finished to reflect the heat of the sun away, achieving  higher solar reflection index and reducing cooling costs.

Greater Sustainability

In addition to energy efficiency, metal roofing systems can be made from recycled steel and then be re-used or recycled at the end of its service life. This capability helps reduce the amount of material headed to landfills and can contribute to points in the LEED green building rating system, among others.

Improved Aesthetics

Sloped metal roofs can be used as a significant design feature on many low rise and mid rise buildings. The range of colors and textures provides architects and other design professionals a full palette of options.

Increased Property Value

Curb appeal and long term performance are common contributers when a property is being assessed for value. A retrofit metal roofing system can certainly help in this regard.

Overall, there are many reasons for choosing a retrofit system for an existing building. Whether to replace a leaking roof, correct the current geometry, meet new regulation or code requirements, improve the aesthetics, or increase the energy efficiency of a building, all of the benefits above can be realized. To learn more about MBCI retrofit metal roofing systems and how they might work on a building you are involved in, visit www.mbci.com/products/retrofit-products.

Installing Metal Roofing Over Asphalt Shingles

Can Metal Roofing Be Installed Over Shingles?

When an asphalt shingle roof wears out, one of the most long-lasting solutions is to retrofit the roof with metal panels, and not remove the asphalt shingles.  While it’s a change of appearance, the metal roofing panels will provide a greater durability and longer service life.

UCI
UCI Retrofit Corporate Office installed 7.2 roof panels over the existing asphalt shingle roof

Installing Metal Roof Panels Over Asphalt Shingles

There are a number of considerations when installing metal panels over an existing asphalt shingle roof.  First, the building codes allow metal over shingles if there is only one layer of asphalt shingles.  A third roof is not allowed, so there must only be one shingle roof in place.

If you’re considering installing metal roofing over asphalt shingles, contact us today to learn more about MBCI’s panel systems.

Choosing the Correct Retrofit Metal Roofing System

Fastener choice is important for wind resistance.  As is the pull-out resistance of the deck. The panel thickness (e.g., 24 gauge), panel width, height of the standing seam, spacing between clips, and clip strength all help determine the overall wind resistance of a metal panel recover installation.  Wind design loads are specific to geographic location and height of the building; work with the metal panel manufacturer to determine the design specifications.  Importantly, use fasteners that are long enough to penetrate through the asphalt shingles and the deck by at least ½” to ensure proper strength.UCI_2

 

Because metal panels run from eave to ridge, the flatness of the existing roof can affect the appearance—the waviness—of the metal panels.  Three tab shingles are quite flat versus laminated dimensional shingles.  Consider installing a base sheet or a #30 underlayment over the shingles before installing the re-cover metal panels.  The uneven surface of the asphalt shingles can be telegraphed to the metal panels, leading to an uneven or wavy surface of the new metal panels.  And, like oil canning, it’s not a performance issue, but homeowners don’t want an unsightly roof.  Spending a few dollars on a heavy base sheet/underlayment is cheap insurance to ensure an aesthetically pleasing roof, and that means a satisfied homeowner who is willing to pay for the new roof!

Benefits of Installing Metal Roofing Over Shingles

There’s a sustainable advantage to installing metal over existing asphalt shingles.  Not removing the asphalt shingles not only saves money but also reduces the amount of waste sent to a landfill.  Roofing tear-off is one of the largest contributors to landfill waste in the U.S. And, while there’s a lot of discussion about the reuse of asphalt shingles (i.e., downcycling) in asphalt roads and bike paths, the reality is that much of the shingle tear-off is not actually reused.  For example, the Colorado Department of Public Health and Environment no longer considers asphalt shingle waste to be a recyclable material.  Not because it’s not recyclable, but because there is no significant market for its use.  These ideas will influence some homeowners, so use them when selling the idea of recovering with metal.

Installing metal panels over existing asphalt shingles is a smart choice.  Design it right, and the new metal roof could last the life of the house.

Contact us today to learn more about how our panels can be installed over asphalt shingles.

Reroofing with Steep-slope Metal Panel Roof System Over an Existing Low-slope Roof: Part 2

Let’s continue the discussion about converting low-slope roofs to steep-slope metal roofs. Part 1 discussed attachment of framing, the new attic space, ventilation and condensation issues, and drainage.

Before After Retrofit

Reroofing Code Requirements 

Converting a rooftop is a specialized type of reroofing.  The codes specifically allow this via an exception that says “complete and separate roof systems, such as standing-seam metal roof panel systems, that are designed to transmit the roof loads directly to the building’s structural system and that do not rely on existing roofs and roof coverings for support, shall not require the removal of existing roof coverings.”

To meet this code requirement—and to not have to remove the existing roof system—the loads must bypass the existing roofing system. This is critical to create a load path from the new structure to the existing structure for dead loads, snow loads, rain loads, and uplift (e.g., wind) loads.

Structural Loads & Wind Resistance

IBC’s Chapter 16, Structural Design, includes all the required information and design methods to determine the dead, snow, wind, and rain loads acting on the building.  The new framing members and their connections, as well as the new metal panels and their attachments to the new framing, must be able to resist the loads acting on the building.  The resistance must exceed the loads.  Most often, wind resistance loads control the design.  Manufacturers and structural engineers should be consulted for material specifics and fastener requirements.

Fire Resistance

Fire resistance for a converted roof needs to meet the requirements of the model codes.  Check with manufacturers for fire classification of the system installed, and ensure it meets the minimum class (A, B, or C) required in the project location.  See the blog “Fire resistance of metal panel roof systems” for more information.

Insulation

For all types of reroofing, the most recent insulation requirements need to be met.  In most cases, additional insulation will be necessary.  Insulation can be placed at the attic floor (i.e., on top of the existing low-slope roof) or directly under the new metal panels.  Where the new roof meets the wall is very important for continuity of the overall building envelop insulation; lack of continuity is energy inefficient and may be a point of condensation.  The location of the new insulation needs to be coordinated with the ventilation plan and condensation potential should be considered. See Part I for more information.

While reroofing with metal can be an aesthetic improvement and solve leak issues, structural loads and wind resistance, fire resistance, and insulation requirements are necessary considerations when converting from a low-slope roof to a steep-slope metal panel roof system.  Don’t overlook the basic code requirements, or the need to deal with heat, air, and moisture issues of the new attic space.

Reroofing and the Building Code

Reroofing is and always will be the predominant project type in the roofing industry.  Roughly 70-90% of all roofing projects (depending on the year) are performed on existing buildings.  Understanding the reroofing requirements in the building code is critical to proper design and construction.  And fortunately, the reroofing requirements are not all that complicated.International Building Code

The 2015 International Building Code, Section 1511, Reroofing provides the building code requirements when reroofing.  Reroofing projects are divided into two types: recovering and replacement (which includes full removal of the existing roof).

Metal panel reroofing projects must meet the same fire, wind, and impact requirements for roof systems for new construction; however, they do not need to meet the minimum slope requirements (¼:12 for standing seam; ½:12 for lapped, nonsoldered and sealed seams; 3:12 for lapped, nonsoldered, non-sealed seams) if there is positive drainage.  Also, reroofing projects do not need to meet the secondary drainage requirements (i.e., installation of emergency overflow systems is not required).

The requirements for metal panel and metal shingle roof coverings are in Section 1507.4, Metal roof panels and Section 1507.5, Metal roof shingles of the 2015 IBC.  These apply for new construction and reroofing, and include information about decks, deck slope, materials, attachment, underlayment and high wind, ice barriers, and flashing.  The 2012 IBC has the same requirements; the 2015 IBC added new language about deck slope and attachment requirements for metal roof panels.  Nothing was changed for metal roof shingles.

In general, recovering is only allowed if there is one existing roof in place, except if a recover metal panel roof system transmits loads directly to the structural system (bypassing the existing roof system).  This provides a great advantage for metal panel roofs!  The existing roofs do not need to be removed, but new supports need to be attached through the existing roof (typically a metal panel roof) directly into existing purlins.

If metal panels or metal shingles are installed over a wood shake roof, creating a combustible concealed space, a layer of gypsum, mineral fiber, glass fiber, or other approved material is required to be installed between the wood roof and the recover metal roof system.

Good roofing practice is codified in the reroofing section of the IBC; contractors who design and install a recover or replacement metal roof are legally required to follow locally adopted code requirements.  And, of course, all metal roofs must be installed according to the manufacturer’s approved instructions.

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