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Measuring for a Metal Roof: Considerations and Tips

Posted on August 25, 2020March 29, 2022 by Michael Fuselier

Getting an accurate measurement for your metal roofing panels may seem like a no-brainer, but it’s not quite as simple as length x width. The many complexities of a roof must be taken into consideration in order to ensure your numbers add up. For instance, anything that intrudes upon a roof plane needs to be included in drawings with labeled measurements as these conditions will all affect the measurement but are sometimes overlooked.

Let’s look at some specific conditions to consider before getting out the measuring tape as well as some handy tips for installers.

Building Conditions to Consider Before Measuring

The type of roof system

Is it going to be a standing seam roof system or an exposed fastener system? Once you’ve decided on your roof type, we recommend reviewing all of the conditions/details on the roof. If it’s a standing seam roof, will the roof system need to float? If so, where will it be pinned, and what direction will it float?

At MBCI, we have published installation technical manuals for installers and erectors to utilize in order to familiarize themselves with how to adjust for ridge conditions or end lap conditions, for instance.

Is it a new or existing metal building?

If it is an existing building, are there new or updated building codes to consider? This could possibly dictate panel type, gauge, or width, or require additional framing members that could impact the final measurements.

What is the purlin spacing?

The panel break at the purlin for an endlap condition will need to be considered.

Are there extensions, overhangs or penetrations?

Include any roof extensions or overhangs that may not be apparent at first glance. Any and all roof conditions should be considered when calculating panel and trim length, including any roof penetrations such as pipes, roof curbs, skylight hatches, etc.

The manufacturer’s details will aid in determining such things as panel hold back at the ridge, or panel overhang at the eave or gutter. Also, roof or slope transitions, and panel hems should be considered.

Insulation

The thickness of the insulation could determine or dictate the fastener type used.

Measuring Tips

Field verify the roof slope. The contractor should gather the field dimensions so measure when the framing is in place. While you can measure off of a set of plans, it’s not a definitive way to do things because things change in the field.
The structure should be square while you’re measuring. Scaling from plans may get you close, but measuring erected framing that is plumb and square is the most accurate.
You should measure multiple spots.
It’s a good idea to use a plan view of the roof or sketch a bird’s eye view to record your measurements.
Record your measurements in the units of measure that your manufacturer uses, typically feet and inches, to avoid errors.
The erector may elect to add a few inches to the length of the panels at a hip or valley to remedy any cutting mishaps since these panels will be field cut to the hip or valley angle.
Some contractors include one or two extra panels at the longest length for any errors or jobsite damage.

Ultimately, the takeaway is that any differential when measuring metal panels for installation could affect a building’s performance, so it’s important to keep all potential scenarios that could affect measurement accuracy in mind—throughout the entire process. To find out more about the proper way to measure a roof for metal buildings or to schedule training, contact your local MBCI representative.

Tips for Selecting and Field Applying Touch-Up Paint

Posted on November 14, 2019 by kbuchinger

Metal roofing and wall panels routinely come from the factory pre-finished a durable, baked-on paint finish that covers the Galvalume^®-coated steel surface. This production occurs in a controlled environment, which helps create a consistent product, and allows metal panels to last decades with minimal maintenance. It turns out, however, that the biggest threat to a metal panel’s paint coating can happen during panel installation. Tools, fasteners and other installation-related items and activities can scratch or damage the finish, requiring touch-ups to the paint. If you experience this, here are some touch-up paint tips to keep in mind.

Assess the Damage

First, determine how noticeable the scratch is. Do you have to be close to see it, or can you see it easily from several feet away? Generally, if the scratch isn’t noticeable and has not penetrated the Galvalume coating, its best to refrain from doing a paint touch-up. This is because touch-up paint can’t match the fade resistance of the original baked-on pre-finish, and if the Galvalume is still intact, it will still protect the steel beneath the scratch.

On dark or bright colors in particular, the touch-up paint will fade much more quickly than the original paint. Often, the end result is that touch-up paint is more noticeable than if the scratch is left alone. On the other hand, if the scratch is noticeable and needs a touch-up, there are some best practices to follow. It’s important to note though, that if a large area of the panel is damaged (more than 10–15%), then it’s best to just replace the panel.

Getting the right touch-up paint

Metal panel manufacturers recognize that there may be a need for minor paint touch-ups in the field. So, most offer small containers of paint conducive to field work. These paints are specifically formulated to match standard color offerings, and have properties that make them compatible with the factory finish. Therefore, it’s important to always buy touch-up paint from the manufacturer that produced the original panels. Never ask a paint store to match colors based on a piece of panel or trim. Doing so may get a color match, but it won’t contain the other protective properties of the paint coating you receive from a manufacturer.

Choice of touch-up paint application

Touch-up paint for field application is often available in three types of containers: paint pens, small bottles and spray cans. Usually, the best choice for a scratch is a paint pen. Touch-up paint pens have small, precise tips that can fit into scratches, allowing it to only apply paint where needed. For larger scratches or scuffs, manufacturers offer bottles of paint (with a small brush) similar to those used for nail polish. Generally, these are best for dings on the panel.

Spray cans are also available, and are ideal for painting small accessories like plumbing vent pipes. Don’t use spray cans to conceal a scratch because they apply much more paint than necessary. This can cause unsatisfactory results as the paint weathers and fades differently than the original paint.

Using touch-up paint

When performing a paint touch-up, it’s important to make sure the area in and around the scratch is clean and dry. Wipe down the area as needed, then dry it completely before applying any paint. Afterward, paint the surface using the least amount of paint necessary. This eliminates excess paint on the pre-finished panel. Paint pens are ideal for this since they apply less paint than a nail polish-type bottle or spray can. Once the touch-up paint is on the panel, it will need time to dry. During drying, make sure that dust or other contaminants do not embed into the wet paint.

Consult the metal panel manufacturer

To ensure you or your maintenance professional properly select and apply touch-up paint, be sure to check all warranty and installation requirements and resources with the metal panel manufacturer. They can help ensure you get touch-up paint that matches the paint originally used on your panels and that you take the right steps to ensure warranties remain intact. MBCI offers metal panel touch-up paint for industries and applications including:

For more on metal roof and wall panel finishes, colors and touch-up paint techniques, contact your local MBCI representative.

Cutting Metal Panels Properly On Site

Posted on October 17, 2019 by kbuchinger

Cutting metal panels on site is an often-necessary part of installing metal roofing and wall panels. However, using the right tools and methods to ensure the panels remain damage-free is vital. Using the wrong tools can result in rust, rust stains, the voiding of warranties and diminished building service life. In this blog post, we’ll share several common field-cutting techniques and best practices that help ensure good results.

Maintaining Longevity When Cutting Metal Panels On Site

When metal panels are made in a manufacturing facility, the tools and methods used to cut the coated metal coil help protect the cut edge from deterioration like corrosion. When cutting metal panels on a jobsite or in the field, protecting any cut edges is just as important. To understand how to field-cut metal panels without sacrificing the quality and protection delivered from the manufacturing facility, you must first understand the what protects the panels. Most often, metal roof and wall panels are fabricated from Galvalume®-coated steel coil because of its proven longevity. Not only does the Galvalume coating protect the surface area of the metal panels, it has also been shown to be effective along the thin edges of the metal too, as long as those edges are cut properly.

During fabrication, the Galvalume metal panels are cut to length either by shearing while flat before entering the roll former, or by means of a profile shear as the panels exit the roll former. Either method tends to “wipe” the Galvalume coating across the cut edge of the metal panels. This provides superior cut-edge protection from corrosion.

Likewise, when panels arrive on site, any needed field cutting should address the same concerns of protecting the edge of the steel from corrosion. Of course, there are ways of doing the field cutting correctly. However, there are also poor strategies that can lead to real problems. The following are examples of common field cutting tools and the best practices for good results.

Common Tools and Methods for Cutting Metal Panels On Site:

Aviation Snips

Red and green aviation snips are a good choice for small cuts on metal panels, such as around pipe penetrations. These snips will wipe the Galvalume® coating in the same way as factory shears, making them a good choice.

Electric Shears

Electric shears are optimal when making lengthier cuts along the steel, such as cutting a wall panel at a corner or at a door opening. These shears take a ¼” strip of metal out of the panel during the cutting process, which tends to leave both sides of the panel smooth and flat along the cut. Like the aviation snips and factory shears, electric shears will wipe the Galvalume coating and protect the edges.

Mechanical Shears

Mechanical shears are an add-on tool that fit onto a battery-operated impact or screw gun. These shears do not take any metal out of the panel and will leave a slightly wavy edge. Mechanical shears are an excellent choice for bevel cutting standing-seam panels at hips and valleys, since they too wipe the Galvalume coating over the cut edges to offer protection.

Nibblers

A nibbler is a great tool for cutting across corrugations in wall panels to create openings for windows, doors and similar structural additions. A good nibbler typically costs $500-$700 (currently), but is well worth it if you often cut corrugated metal panels. The punch and die in the nibbler tends to wipe the Galvalume across the cut edge as it punches out small, half-moon shaped pieces of panel. However, because these little metal pieces will fall away from the cut, it’s important to contain them so no one walks on them. Otherwise, they can embed in the soles of installer’s shoes and create scratches in roof panels when they walk on the roof.

Skill Saw

Skill saws are an ideal tool for cutting metal panels because of their versatility. This tool can cut either across or parallel to corrugations, whether straight or at an angle. When using a skill saw, it is critical to use a saw blade that cuts cool. Otherwise, the Galvalume coating can melt along the cut edge and become ineffective. In particular, do not use an abrasive blade, which will generate heat and damage the coating.

Panels cut with abrasive blades corrode. A cool-cutting blade leaves a smooth edge.

Additionally, its vital to avoid cutting panels on the roof or above other panels. A skill saw blade will throw considerable amounts of steel debris into the air and down onto any panels below. This debris, called swarf, will quickly rust and ultimately cause rust spots in the panels. If enough swarf gathers in one spot, it can rust through the panel.

Steel swarf, like this collected at the ridge will rust through the panel.

Which Tools Should To Avoid When Cutting Metal Panels On Site:

Tools that should never be used include:

Torches
Cut-off saws
Reciprocating saws
Hacksaws
Grinders

All of these tools will melt the Galvalume^® coating, causing edge rust just like an abrasive blade would. These tools also throw a lot of steel debris (swarf) onto the panels they cut. This debris will be hot and will embed into the panel coating. This can cause rust spots and bigger problems down the road.

In conclusion, using the right tools and following metal panel manufacturer recommendations when cutting metal on site will help ensure that the panels remain damage-free and the final installation will be a fairly seamless process. Using the wrong tools can result in rust, rust stains, and the voiding of warranties. For more on best practices and recommendations for on-site cutting and installation of metal panels contact your local MBCI representative.

Metal Roof Seaming: Best Practices for Ensuring Weathertight Seams

Posted on June 27, 2019August 15, 2024 by Randy Tweedt

It would seem logical that the most important field installation process for a standing-seam metal roof is the actual process of creating the weathertight seams that connect the metal panels together and ensures the structural integrity of the roof. Perhaps for many different reasons, however, this critical seaming process is not always given the proper attention it deserves, nor are installers given the proper training required to ensure installation runs smoothly. This approach can cause some serious issues, not the least of which is the voiding of a manufacturers warranty or the discovery of roof leaks and the resulting damage.

To help, here are some best practices for readily and successfully carrying out the metal roofing seaming process:

Personnel

Because of the critical nature of seaming metal roofs, the crew members doing this work should be properly trained. Team members who will be performing this work should not perform the seaming without having participated in the appropriate installation training required to ensure the seaming process is appropriately managed. Most roofing manufacturers offer installation training that many installers take advantage of—and this training opportunity should be taken advantage of by the staff who will be doing the seaming.

Seaming Equipment

It is very important that the seaming equipment being used is matched to the specific roof panel system being installed. Manufacturers routinely rent out this equipment in order to be sure that the metal panel profiles are installed properly and are not compromised through the use of generic equipment or that of another manufacturer. Using the wrong equipment can end up being costly for everyone if panels and seams are ruined in the process.

Hand Crimper

As metal panels are set in place, they are often secured with metal clips, spaced according to engineering and construction needs. Hand crimpers are used to form the seams around the clips as well as any end laps. This process must not be overlooked as improper hand tooling is the number one cause of faulty seaming. To ensure costly mistakes aren’t made, follow the process described in the “Field Seaming Tool Manual”. This manual should be provided with the equipment and reviewed in training.

Electrical Sources

The next step will involve the use of an electric seamer which obviously needs a source of electricity to operate. However, not just any electrical power source will do. Almost all professional seamers have an AC/DC motor that will require 10 or 15 amps and 120 volts. A dedicated electrical circuit—preferably from a temporary electrical pole or an existing building electrical panel—is the best and most reliable way to go. A generator with 15 amp capacity dedicated to be used only for the seamer (in order to avoid power surging) may be acceptable as well. In either case, the power line to the seamer needs to be 10-gauge (minimum) cord. It should also be no more than 200 feet long (to avoid power drop).

Electrical power sources that are NOT acceptable include outlets from a powered man lift or a generator that is not dedicated to only the seamer. (This includes a generator that is part of a welding machine.) Check the manufacturer’s requirements for any other restrictions that can damage the seamer. Skipping this step can place the responsibility for repair or replacement onto the installer.

Electric Seamer

Once all panels are in place, the hand crimping is done and the power source is set. Then, electric seaming takes care of finishing the roofing system. Again, consult the seamer manual for proper procedures, including which direction the seaming should be done. (Seaming can either be done up or down the roof depending on direction of roof installation.) The electric seamer includes a switch for the operator to control the starting and stopping of the process.

On low-slope roofs, the operator should walk alongside the seamer to be sure nothing is in its path and that the seam is done properly. While stopping and re-starting is fine, the seamer should never be removed in the middle of a seam. Doing this makes it very difficult to set it back in exactly the same spot again. If something appears to be wrong with the seamer or the seams being produced, then don’t keep using it. There is no point in damaging multiple roof panels if any one panel indicates that things aren’t going right. In this case, contact the manufacturer right away for assistance or replacement of the seamer.

Safety

Electrical seamers are heavy and—if not used and secured properly—can cause harm or injury. Therefore, they should always be tied off with a safety line—the same type used for workers—not a common rope and definitely not the electrical cord. The safety line should be properly secured to the seamer and then attached to something rigid on the building. Never attach this to a person who could be pulled off of a roof by it.

Cleaning

Before use each day, check the electric seamer and remove any oils, debris or dirt. Make sure the seamer is unplugged from the electrical power source before you begin cleaning. Also, check the grease level in the machine daily and only add a little bit (2-3 pumps from a grease gun) as needed. Too much will cause the grease to leak out onto the roofing.

Following these pointers should help assure the safe and efficient use of the right seaming equipment when installing roofing panels. To find out more about proper seaming or to schedule training, contact your local MBCI representative.

Choosing Metal Roofing Types

Posted on November 29, 2018 by Bruce Green

All metal roofing is not the same. There are different profiles in different shapes for different reasons and to suit different performance needs. How to choose? Here’s the process that metal building engineers go through at MBCI to zero in on the most economical selection that will still meet the performance requirements of a particular metal roof project.

Snap Together Trapezoidal Panels

Offered by MBCI under the name Ultra-Dek®, the trapezoidal shape is among the best for channeling water off of the roof. However, because of this shape, it is most appropriate for typical sloped roofs with single plane roofs areas free of valleys or hips. It’s snap together installation makes it quick and easy to install economically with wind resistance capabilities adequate for many situations. It also carries basic air leakage and water penetration testing approvals.

Mechanically Seamed Trapezoidal Panels

For roofs that require a higher degree of performance than snap together systems can provide, MBCI Double-Lok® panels can be considered. The mechanically field-seamed, trapezoidal legs provide higher wind and water resistance with test results to satisfy UL-90, FM ratings, and Miami Dade County approvals. This makes them ideal for many industrial, commercial, and architectural roofs without hips and valleys that are subject to higher wind and rain demands. While the material cost for the panel is the same as for the Ultra-Dek®, there is more labor cost due to the mechanical field-seaming compared to the snap together installation. The Double-Lok® panel is also used often for retrofit installations over pre-existing metal roofs either to update the roof or to provide additional insulation. In either case, there is no need to disrupt the existing roofing or structure below allowing for a very cost-effective solution. Check with MBCI on the details of how to properly do a retrofit with these panels though to be sure things work out as intended.

Vertical Legs with Mechanical Seams

Regardless of which metal roofing type you choose, they all use high grade steel in standard gauge thicknesses and can be specified in many colors.

In cases where the trapezoidal legs aren’t appropriate or desired, then vertical leg, standing seam metal panels are the next logical choice. The MBCI BattenLok® HS system uses 2” tall legs that are mechanically field-seamed once along each panel joint to create a high strength, structural standing seam roof system that can be installed directly over purlins or bar joists – no additional solid substrate is required. It is also capable of transitioning from roof to fascia with the use of accessory seam covers.

Double Seamed Vertical Legs

In cases where very rigorous weather conditions may be encountered, the MBCI SuperLok® roof panels provide the highest degree of roof performance. While the manufactured SuperLok® roof panel is essentially the same as the single seamed BattenLok® panel, the profile is modified slightly to allow for standing seams to be rolled over twice, thus creating a stronger, thicker seal between adjacent panels. Once again, there is no difference in the material cost between the two, but the added field-seaming step will obviously add to the labor cost of this roof choice. Nonetheless, that can be a small price to pay for the higher performance and added peace of mind that the system offers.

While we have pointed out the differences between these four different metal roofing choices, note that there are some basic similarities too. They all use high grade steel in standard gauge thicknesses and they can all be specified in the same wide choice of colors. They are all offered in multiple panel widths, although check with the manufacturer to be sure the width you prefer is available for the specific panel selected. They all can be used for low slope applications down to ¼” per foot except for the retrofit solution which requires a 3:12 pitch. Finally, they all do have some minor variations in the profile which can help with the final desired appearance of the finished roof on the building.

To find out more about the differences in roof deck types and how to choose the best ones for on a metal roof that you are involved with, contact your local MBCI representative, and sign up for our newsletter to subscribe to our blog.

Appropriate Standing Seam Clips for Roof Panels

Posted on November 2, 2018 by Jason Allen

Part of the beauty and appeal of standing seam metal roofs is that the fasteners holding the metal panels in place are concealed. That gives the roof its clean, continuous appearance that is often desirable, but it also avoids the issue of potential roof leaks around exposed through-fasteners. Concealed fastening doesn’t mean that there aren’t any fasteners, though, it just means they are installed out of sight – underneath the panels. The industry standard approach is to use a metal clip that fits over the edge of a panel and that is secured with a screw type fastener to the structure or substrate below. Then it is covered by an adjacent panel or trim. The important thing to know is that not all panel clips are made the same – for good reasons.

What determines the type of panel clip to use? Here are the most common things to keep in mind:

The Manufacturer

Each manufacturer of metal roofing typically has a range of metal panel types, profiles, and brands that have their own traits and characteristics. As such, they need clips to match and fit with the manufactured panels. Hence, the first place to start with panel clip selection, is for the roofing manufacturer to be clear on the options and choices available that are compatible with their roofing products.

Building Size and Type

Fixed clips (left) and floating clips (right) are two commonly used types of clips.

Manufactured metal buildings that include metal roofing commonly use very predictable, coordinated systems. Accordingly, a standard, one piece, “utility clip” is commonly used, primarily for snap together roof panels, on metal buildings that do not exceed certain widths causing undue expansion and contraction. One piece clips allow the roofing panels to expand and contract within the clip profile, but there are limits based on the amount of movement tolerated. Alternatively, in projects where the roofing is attached to something other than a metal building frame or where standing seams are used to secure the panels together, it is advisable to use a two-piece or “floating” clip. In these cases, a base piece is secured to the structure or substrate and the clip fits both into the base and over the roofing panel where it is seamed or folded into the vertical leg of the panel. Using this approach, the clip expands and contracts directly with the metal panel thus moving across the base and keeping the roofing attached.

Insulation

Roof insulation comes in different thicknesses, appropriately so for different climate zones and different roof designs. Since energy codes require at least some of the insulation to fit between the underside of the metal roofing panel and the structure (i.e. above the metal roofing purlins), the metal panel clip needs to be the right height to reach the full height of the insulation up to the top of the roof panel. Hence, manufacturers offer different sizes and heights of panel clips designed to work with different heights of insulation. In many cases, they also recommend the use of a thermal spacer underneath the clip to separate it thermally from the steel structure below. Note that the thermal spacer thickness is dependent on the insulation thickness over the steel purlin only, not the thickness of any insulation under the purlin.

A certified installer should install your standing seam roof to ensure proper installation of clips.

Other Factors

The panel clips connect the roof panels to the roof structure, so they need to be installed in a manner that allows them to do that job under normal and demanding circumstances. The driving issue in this case is not keeping the panel down, but preventing it from blowing off in a strong wind. Therefore, a structural engineer or other design professional may need to determine the proper spacing of the clips, the type and size of fasteners (i.e. screws) to use, or similar important details. Similarly, the proper installation of clips so that they seat and nest the way they are intended, means that qualified and certified installers / erectors should be used. In this way, roofing crews with the needed experience and training can help assure that the whole roofing system, including the panel clips, are installed properly.

To find out more about the most appropriate panel clips to use on a metal roof that you are involved with, contact your local MBCI representative.

Preventing Roof Damage from Rusted Fasteners

Posted on August 10, 2018 by kbuchinger

These days, the majority of metal roofs are made from Galvalume coated steel, which typically carry a warranty against perforation due to rusting for a period of 20 years. A study on Galvalume standing seam roofs (SSR) conducted at the behest of the Metal Construction Association (MCA) showed that a properly installed Galvalume SSR can be expected to last 60 years or more. However, the caveat is “properly installed”. One of the major issues that will drastically reduce the service life of a Galvalume-coated roof is the use of non-long-life fasteners in exposed locations.

Anytime you have an exposed fastener on a metal roof, you risk rust—the term commonly used for the corrosion and oxidation of iron and its alloys. While a little rust might not seem like a big deal, its presence can actually be a harbinger of severe damage to your metal roof panels if not caught early, or ideally, stopped before it ever has a chance to start.

The issue is most prevalent on R-panel roofs due to the use of exposed fasteners. And even with standing seam roofs, which use clips and are typically referred to as a concealed fastener roofs, there are exposed fasteners as well, most often at the eave, the end laps and at trim, such as ridge flash, rake trim, and high-eave trim.

Prevention

The best recommendation for any exposed fasteners (meaning they are exposed to the weather and other harmful elements), is that they should be long-life fasteners. When you don’t use long-life fasteners, they start rusting with exposure to moisture and, over time, the rust virus stretches down to the roof, causing severe and often irreparable damage.

Suppose you have a metal roof that is 10 to 15 years old. Depending on the environment, the roof could be in excellent shape—except for where those screws are; you can have holes right through the roof at the fastener locations. More people than ever are starting to realize they’re supposed to use a long-life fastener, in a case like this. We see a lot of roofs when we inspect them for weathertightness warranties. What often happens is a worker on the roof may have just grabbed some screws that were handy without thinking about the kind of screw or the inevitable chemistry that could potentially cause rusting. Or, you may have a situation where there is some type of accessory put on the roof by another trade, perhaps a plumber or an HVAC installer—and maybe they didn’t use long-life fasteners.

The best recommendation to mitigate this potential problem is two-fold. First, make sure roofing installers know to use a long-life fastener at every exposed location. Secondly, make sure that every other contractor working on the roof that you’re responsible for knows to use long-life fasteners with whatever they’re doing.

A long-life fastener (left) can withstand the elements and prevent rust buildup longer than other fasteners. A regular fastener (right) will begin to rust upon exposure to moisture.

What if rust does occur?

One question frequently asked is: if the fasteners do become rusty, do you have to replace all the panels? If you catch the problem before the rust virus makes its way down to the roof itself, you can just change out the screws. However, if the rust has compromised the roof, you very likely would have to change out all the panels, at the least everything that has been affected—just because of one little spot. Truthfully, if the rust is in one spot, it’s probably all over.

Another thing worth mentioning is if aluminum panels are used along with typical long-life fasteners, it could still rust, especially if the roof is exposed to salt spray (think close to the coast). The answer in this case is to use a stainless steel screw, which are long-life fasteners (but not all long-life fasteners are stainless steel).

Be aware from the start.

It’s crucial for installers and contractors to take notice and order the right fasteners from the start so that problems can be avoided.

Also, after some wear and tear, if subsequent work is done on the roof, everyone involved should take note. For instance, you buy a building and somewhere down the road you decide to frame out a small office and add a bathroom. You’d need a water heater, so a plumber goes on the roof, puts in pipe penetration and doesn’t use long-life fasteners. The onus would be on the owner to ensure that everyone performing work on that roof—no matter when—is using long-life fasteners.

Conclusion

The best-case scenario with a metal roof is to get the right fasteners to begin with. However, if the roof is already installed, the next step is to be on the lookout for rust and if you notice it, consider that it might be because of the fastener.

If that’s the case and you catch it early—when it’s just the screws that are rusting but the rust virus hasn’t yet transferred down onto the roof, you can just change out the screws with the proper long-life fasteners. We recommend doing a roof inspection at least once a year. If you see any loose or rusty screws, replace as needed.

For more information on MBCI’s broad selection of metal roof and wall panels, contact your local MBCI representative.

Quality Control Accreditation Programs for Metal Roofing Products

Posted on April 11, 2018March 30, 2022 by Jason Allen

Performance-based building product testing and accreditation is a critical piece of just about every aspect of construction—affecting everyone from the manufacturer to the installer and ultimately to the owner and occupant. These certifications ensure real-world property loss will be prevented and provides protection when certified products are installed correctly.

With roofing being such a vital part of any building project, roofing manufacturers must take certifications for roofing products (in this case, metal roofing products) very seriously. Below, we’ll give a brief overview of the main certifications that we—and other metal roofing companies—test to and are audited for in order for the overseeing bodies to confirm that we’re producing what we’re testing it to. In the simplest terms, these specifications, such as UL or FM, will give the contractor peace of mind that he or she can provide what is spec’d.

At MBCI, we have several certifications through which we have ratings. These include:

1. UL (Underwriters Laboratories).

UL certifies roofing materials and roof assemblies for fire performance, hail resistance and/or resistance to wind uplift. Roof deck assemblies are investigated for performance under internal fire exposures and for uplift resistance. MBCI does a good deal of testing and we have UL constructions for many of our roofing products. We get the UL construction number, impact ratings and fire ratings. UL does quarterly audits in the manufacturing areas to make sure that we’re producing the panels the way we test.

2. IAS (International Accreditation Service) certification.

IAS accreditation programs are based on recognized national and international standards that ensure acceptance of its accreditations. To meet this standard, MBCI is “Part B” of the process, as we are responsible for the components. The auditor comes in to certify that we do what we say we do. Once IAS accreditation requirements are met, the company receives a certificate of accreditation.

3. FM (Factory Mutual) approvals.

MBCI has three roofing products that are FM approved for wind uplift standards, hail resistance, internal and external fire ratings. For each, we test the product and FM comes out yearly to do an audit.

This is an example of FM wind uplift testing.

4. Dade County roofing product approvals.

Miami-Dade and Broward Counties are classified as High Velocity Hurricane Zones (HVHZ), which are rated as 150 mph plus winds. It is Florida’s highest rating. An updated testing approval process has been instituted for building products and materials used in these counties. The purpose is to mitigate damage caused by wind-borne debris resulting from hurricane-force winds. MBCI does testing and this stringent certification is applicable for anything that ships into Dade County or Broward County in Florida. Product Notice of Acceptance can be located on the Miami-Dade website for roof and wall panel systems that are Dade County approved.

Safety and performance are the most important goals. All in all, these certifications ensure that we, the manufacturer, are doing our job and that customers are getting everything they’re paying for. For more information on MBCI’s product testing, please contact a sales representative.

Ventilated Metal Roofing Systems

Posted on January 25, 2018 by kbuchinger

Metal roofing is commonly installed on residential or light commercial buildings, where longevity and aesthetics are a priority. When those buildings are wood framed or use roof sheathing, the desired results can still be achieved, as long as some basic guidelines are followed. One of the most fundamental items to address is making sure that the roof system is properly ventilated in a manner that works with the rest of the building construction. Let’s take a look at the two most common means to achieve that.

Ventilated Attic:

Conventional residential roof construction typically involves a trussed or rafted roof system with insulation installed along the ceiling line and a ventilated attic above it. The premise here is that the ceiling is sealed tightly to prevent any conditioned air from entering the attic, but if it does, then any moisture in that air is ventilated out of the attic, preventing any build up and potential damage.

The most effective way to ventilate an attic is with continuous vents along the soffits and a corresponding continuous vent along the ridge. The International Residential Code (IRC) recognizes this approach and provides the formulas for determining the proper amount of net free vent area (NFVA) required for the total roof assembly. It then goes on to state that 50 percent should be split between the ridge vent and 50 percent along the total soffit area. Some building experts suggest, however, that 60 percent along the ridge and 40 percent along the soffits will provide a slight pressurization of the attic and help with the desired proper venting flow.

Either way, the overall intent is to create a situation where outdoor air is moving freely in through the soffit vents and up through the ridge vent. The continuously moving air then helps keep the roof sheathing, and the roof cooler than it would be when compared to sitting in the sun without the ventilation – on the order of at least 2-3 degrees Fahrenheit.

Ventilated Roofing:

Not every roof system is built with an attic and insulated ceilings. Sometimes, the roof deck defines the building enclosure either in the form of an upper floor ceiling or as a cathedral-style ceiling and roof system. In some of these cases, insulation may be installed between the roof framing which still requires ventilation between the roof sheathing and the insulation on the order of an inch minimum of air space (2 inches preferred), as in an attic.

In other cases, the insulation may be rigid foam that is installed above the roof deck or sheathing. Here, the insulation needs to be thick enough to keep the exposed ceiling warm and prevent any condensation inside the structure. The International Energy Conservation Code prescribes the minimum R-values of insulation based on climate zones, and typically, the required amounts for energy control also assure condensation control.

Above sheathing ventilation (ASV) is achieved by having continuous air flow between the roof sheathing and the metal panel system.

Nonetheless, if a layer of wood sheathing is placed directly on the insulation and then the metal roofing placed directly on top of that, the metal roofing will tend to get warmer in the sun than in a ventilated condition. Therefore, metal roofing manufacturers often recommend providing an air gap between the metal roofing and the sheathing. This is achieved with furring strips ran vertically to assure air flow, and then run horizontally to support the roof. The spacing and details of these supports should be determined by a structural engineer who can perform the needed analysis and calculations, taking into account the panel strength and imposed loads from snow, wind, etc.

Is this approach effective? A series of studies undertaken at Oak Ridge National Laboratory and sponsored by the Metal Construction Association has determined the answer is yes. These studies used a common asphalt-shingled roof without any ventilation above the sheathing as the control case. Then different versions of a metal roofing system with ventilation between the sheathing and the roofing were tested and compared to each other and the asphalt-shingled roof. The results found that “all test roofs were highly effective in reducing the heat flows through the roof and ceiling, and in reducing the diurnal attic temperature fluctuations.” (References below)

Clearly, paying attention to ventilating the roofing system, regardless of the type of construction, can make a difference in the overall performance of a roof. To find out more about ventilated roofing systems for a current or upcoming project, contact your local MBCI representative.

References:

Performance Evaluation of Advanced Retrofit Roof Technologies Using Field-Test Data – Phase Three Final Report

Authors: Kaushik Biswas, Phillip Childs, Jerald Atchley

Volume 1 Published: May, 2014 ORNL/TM-2014/141

Volume 2 Published: January 2015 ORNL/TM-2014/346

Prepared by OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee 37831-6283

Managed by UT-BATTELLE, LLC for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-00OR227

Proper Fastening Helps Prevent Leaks and Callbacks

Posted on December 18, 2017 by Randy Tweedt

Installing metal roofing and siding requires placing and aligning metal panels over the structural supports. But ultimately it requires installers to spend a fair bit of time fastening them in place, typically using a great many fasteners. It is easy to get complacent about this repetitive activity, but the reality is that every fastener plays a crucial role in the integrity and longevity of the installation. Properly selecting, installing, and using the right tools, allows for a proper fastening process that assures a weathertight installation. But if a few fasteners are installed poorly, causing water or air leaks, then the installer is called back to correct the condition. Do a lot wrong, and warranties can be void, with the durability of the building left compromised, possibly requiring a total do-over.

What’s the difference between a good fastening installation and a problematic one? Here are some of the things to pay attention to onsite:

Fastener Types:

The most common type of fasteners used in metal buildings are self drillers, which vary based on diameter, length, head shape, and material. They are also specifically designed for use in metal substrates. Different fasteners are also available for wood versus metal, and either type can be sized for different substrate and panel thicknesses. Zinc alloy or stainless steel fasteners are common choices for durability, longevity, and avoiding galvanic action with other metal products. Selecting and using the right fastener type for each of the different locations on a metal building begins with determining what is being attached and what is it attaching to.

Fasteners can also be colored to match the roof or wall panel.

Weathertightness:

Fasteners of any type cannot be relied upon by themselves to keep out the elements. Instead, a sealing washer is used that is compressed between the fastener head and the metal panel as the fastener is tightened to form the weathertight seal. High-performance or long-life fasteners may be required for a durable approach to weathertightness and/or may be required by the metal building manufacturer to receive a weathertightness warranty.

Installation Process:

With the right fasteners onsite, the success of the installation now rests with the field crews. A few minutes to review the different fasteners and match them with the right tools and settings for installation is time very well spent. Since electric screw guns with or without impact drivers are common on the jobsite, it’s easy to think any tool will do, when it probably won’t. The wrong tool at the wrong setting can place too much torque or other force on the fastener, causing it to crush or damage washers or even the metal panels. Impact drivers are rarely needed in most cases and, while the fastening needs to be tight, overtightening is never a good thing.

Fastener Locations:

In addition to weathertightness, fasteners provide a structural function as well. Their location and spacing will directly correlate to the ability of a panel to resist wind and other forces after installation. Therefore, it’s always best to use information prepared by a professional engineer on the proper fastening locations, spacing, and sizes. The calculations behind such information can prove to be the difference between a successful installation and one that creates problems.

Understanding the importance of fasteners and the role they play in the integrity of the building, and corresponding warranties, allows installers to see beyond the repetitive task of fastening and into the craft of assembling a durable, long-lasting building. To find out more about fasteners for metal products and systems for your next project, contact your local MBCI representative.