Steep Slope Metal Panel Roof Retrofitting Over An Existing Low-Slope Roof: Part 2
Metal Panel Roof Restoration & Installation
How to Avoid Common IMP Installation Mistakes
Insulated metal panels (IMPs) are ideal for many roofing and wall applications. They are considered a top-of-the-line choice known for their superior insulation value, high performance air barrier, design flexibility, and fast installation. The simplicity of installation creates a high-performance building envelope. The many design options provide a versatile building solution for commercial, industrial, and institutional projects.
Sounds great, doesn’t it? What’s the catch? Well, those benefits won’t mean much if proper care is not taken during the installation process to ensure you’re getting what you paid for. Potential consequences can span the gamut—from minor aesthetic headaches to extremely costly errors such as leaks and structural issues.
Here are some ways to avoid common pitfalls when installing IMP panels on your next metal wall or roof project.
1. Pay attention to the manufacturer’s product installation manuals.
Installation manuals are not just for show! Even the most experienced installer should read, review and understand the installation guide before installing IMPs, and the panels should always be installed in accordance with the project’s installation drawings.
Don’t simply rely on the “what-you’ve-done-before” mindset. Take the time to review the specifics for every individual project. In addition to providing the information needed to execute a successful install, it can also give installers an opportunity to build upon their own knowledge base. One of the most common errors is related to proper receipt and handling of the panels. Investing a few minutes before the project starts and at the start of each day to review key topics helps avoid costly errors and improves production.
If you have a question or something does not seem right stop and call the manufacturer. It is always best to address a problem up front than try and fix a problem after the building is in operation.
2. Equipment check. Do you have what you need?
To keep your IMP installation on track, it’s imperative to ensure you have the equipment you’ll need for the job. Does your project need one or two forklifts, is a crane a better option? Will your project include longer-length IMPs being installed in a vertical orientation? If so, you may need special lifting equipment so as not to damage the panels. Whatever the details, crews need to be prepared to receive a project’s specific materials on site. A little advance planning will ultimately save you time and money by reducing labor and avoiding costly mistakes.
3. Don’t assume every IMP application is the same.
All buildings are not created equal. Just because a construction crew has had experience installing insulated metal panels on past jobs, doesn’t mean they can assume the process will be exactly the same every time. There will always be specific conditions and variables that need to be taken into consideration. Techniques used for vertical industrial panels will be different for horizontal architectural panels.
The vapor barrier (a key function of an IMP) is a great example of how a miscalculation can be problematic. Depending on the panel, the vapor barrier may be applied either at the factory or at the jobsite. If the project calls for a cold storage environment, the “warm” side of the vapor barrier will be on the exterior. Alternatively, a commercial or industrial application generally calls for the vapor seal to be on the opposite side of the panel. Confuse placement of the seal and you’re bound to run into problems down the road.
4. Be on the lookout for creases, buckles and framing alignment.
A crease or buckle on the face of a panel might seem like no big deal, but that couldn’t be further from the truth. In fact, framing alignment is one of the most critical aspects to ensure a proper fit-up of the construction as a whole. In terms of the panels themselves, not only will a framing misalignment not LOOK right but can also cause numerous efficiency and performance issues. Installing inexpensive shims can avoid panels needing to be replaced.
Additionally, make sure the first panel is plum and square, if you start right it is much easier to finish right.
Purlins must be level and square and all framing and bracing should be installed before installing panels. (The IMP manufacturer should specify the amount of tolerances allowed.) Also, take care with caulking and taping, foam-to-foam connections (in order to mitigate potential vapor leaks), seaming, and lap joints.
Attention to detail will avoid costly mistakes.
5. Always think ahead.
Being proactive may be the most important piece of advice construction crews need to hear.
For one, be sure to have a panel surplus on hand. You may be of the mindset that ordering extra panels is at worst a waste or at best, not worth the effort. This is a common judgement error that often leads to installation delays. If a crew has only ordered the exact number of panels needed for a job and there is any damage to the product, whether prior to delivery, on-site or during the installation, there a risk to the project schedule. Waiting on replacement panels can wreak havoc on schedules, especially with panels that may need special manufacturing due to custom components, finishes or colors. What do you do with extra panels you don’t need on the initial installation? Building owners can hold on to any surplus panels to be used as replacements, as needed, over the lifecycle of the building. A little preparation today can go a long way.
Other best practices include understanding the project’s site conditions and ensuring crews remain crews up to date on proper installation techniques—including staying current with training and certifications.
By taking this advice to heart, you can exponentially increase your ability to enjoy the many benefits of IMPs and be confident in your investment. For more information on MBCI’s insulated metal panels and proper installation guidelines, we encourage you to contact your local MBCI representative or visit our website.
Insulation Considerations for Metal Building Projects
Once you’ve set your sights on metal panels for your next building project, insulation will be one of the first, and most important, considerations. There are so many variables, though, so how do you know what’s best?
When you’re trying to make a determination of the insulation type, you should first identify what’s driving your decision making. Are your insulation requirements based on external parameters, such as job specs or established code requirements, or is there some other self-proposed condition at play like the end-use function of your building? Do you require upfront cost savings or is long-term value what you’re after?
Here we’ll take a look at some of the most common determining factors and how they might affect your insulation choices.
Depending on whether you’re building in the commercial or residential arena, and what the physical location of your project is, you may have to adhere to strict energy/building codes that will be an unmovable goal post in your decision making.
Are there any local code or project-specific stipulations as far as minimum R-values for the roof or for the walls? What must you be in compliance with? There can be many different aspects of an energy or building code that you will need to research. For example, there may be an envelope solution where the whole building nets out “X” R-value. Or, a prescribed method could be mandated, where each individual component (i.e., windows, doors, walls, etc.) going into that building cannot exceed (or must meet) a particular requirement.
Let’s say, as an example, you have a code that requires you to have a continuous R-value at your structural attachment point. Depending on what that requirement is, it may be harder to achieve that by using a rolled or batt fiberglass systems. You might be able to achieve it much more easily with a componentized system using metal decking/liner and rigid board insulation, or perhaps an insulated metal panel (IMP) may be better suited. In that case, you could be looking at spending more money for that panel system while saving money on the labor … which brings us to the next variable: upfront costs.
Another critical factor is the cost associated with materials and labor of the system you’re going to install. Let’s say, for instance, your needs require a higher-end type installation in order to reach higher R-values or a code-prescribed method. How are you planning to achieve that?
In some instances, you may be looking toward an insulated panel system, which can readily give you those higher installed R-values. While these are extremely efficient systems, there can be a notable bump in the panel material price to get to that same level than if you choose a single-skin approach with a fiberglass or rigid board insulation system. You would, therefore, need to accurately compare the installed costs of the two systems versus just the material alone. Which will be less expensive/more efficient: the multiple components with lower individual costs plus more labor time and expense to assemble OR the potentially higher individual IMP panel price but with less time and expense to install? You will need to look at the project holistically to determine which is more cost-efficient for the specific situation.
Long-term costs, value and end-use functionality
Oftentimes, upfront material and labor costs need to be evaluated in terms of potential long-term savings and value. Some things to consider here are what your big picture needs are for the structure, including an assessment of how it will be used now and in the future. Unlike with dictated codes and regulations, here it may be more a question of wants vs. needs or owner-occupying vs. vendor leasing.
While you might want an R-30 building, for instance, is it economically beneficial for your end use of the building? Let’s use this example: If you’re a homeowner using a metal structure to store relatively non-valuable belongings, how well does it have to be insulated? Is it worth a high price point? In this case, perhaps single layer roof and wall insulation will be adequate for your needs.
If on the other hand, you’re a builder contracted to construct a structure for which interior climate control is critical for the end use—either because of the production to occur inside or perhaps due to food storage or other temperature-sensitive contents—then you might lean more toward an insulated panel system. In another example, if there’s going to be the potential for an abundance of heat or moisture in the building, as with paper products production or wastewater treatment, then you’ll want to be certain that the insulation system you use best resists such an interior climate and doesn’t permit condensation to form. In this example, it is critical that the structure is significantly protected so that moisture cannot become trapped in the roof or wall assemblies leading to reduced building efficiency or even formation of mold.
You should also consider how long it will take to recoup your initial investment. Obviously, for instance, you may spend less money upfront by only putting 4-inch blanket in your single layer metal walls as opposed to choosing to install an insulated metal panel (IMP) system, but long-term, is the money you save by going with the lesser insulation system going to be more than what the energy savings would be over the time that you’re the occupant of the building?
If you’re only going to be in the building for one or two years, or you’re not even occupying the building, you might be tempted to install a lesser expensive system, but then you might be risking not being able to retain tenants or impacting future resale value.
What Are the Insulation Options?
Once you’ve identified what the driving factors are for your insulation system choice, you can match up your needs with most popular options, which are:
Fiberglass insulation solutions, including over-the-purlin systems; cavity fill insulation systems; batt insulation; rigid board insulation via a composite system with metal decking and vapor barrier; or spray-on insulation systems. Alternatively, if a foam core insulation is preferred, it may be worth considering the use of insulated metal panels (IMPs) that are designed, engineered, and fabricated to be compatible with metal building construction as an envelope building solution.
For more specifics on the types of insulation systems that are available, check out this MBCI blog article: https://www.mbci.com/coordinating-roof-insulation-with-metal-building-construction/
Measuring for a Metal Roof: Considerations and Tips
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.
The thickness of the insulation could determine or dictate the fastener type used.
- 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.
Design and Performance Benefits of Insulated Metal Panels
In a prior post on insulated metal panels (IMPs) we reviewed some of the basic things everyone should know about this versatile and lightweight metal building component. In this posting, we will drill down a bit more on the benefits of incorporating IMPs into a new or retrofit construction project. Here are some of the top reasons they are so popularly used in both walls and roofs:
Energy Conserving, Space Saving Insulation
Foam plastic insulation is used between the metal skins of IMPs. Such insulation has been accepted for use by building codes for quite awhile provided it meets certain conditions. IMPs have been tested and shown to meet or exceed all code requirements for construction and for energy conservation too. Part of their appeal over other ways to insulate is that they can achieve high performance in a thinner wall or roof assembly than would be required with other types of insulation, such as fiberglass. IMPs are available in thicknesses that range from 2 to 6 inches and have corresponding R-values from R-14 to R-46 allowing design professionals to select the thickness that matches the energy performance level sought in a particular building. Other insulation types would require thicknesses of at least twice as much to approach the same R-values as IMPs. Further, the metal interior and exterior skins are the only finish material needed so the total panel thickness is very space efficient. Thinner IMPs in the walls and roofs can save space in the building or on the site all while achieving high energy performance.
Durability, Longevity, and Low Maintenance
The manufactured panels are rigid and quite strong. They have been tested for compression, tensile, and shear strength with impressive numbers that come about because of the combination of the rigid foam and steel properties. The surfaces are made from the same long-lasting galvanized and factory finished steel used in other metal wall and roof panels so their resistance to weather, abuse, and even harsh conditions has been proven, making them very easy to maintain. In locations where severe weather and storms are a concern, they can also be specified to meet requirements for heavy winds, hail, and similar concerns. Plus, since the skins of the IMPs are made of noncombustible steel, they provide an ignition barrier as part of an overall fire protection scheme for the building.
Cost Saving Construction
IMPs are an “all-in-one” product that takes the place of many other products and components used in traditional construction. Instead of requiring multiple trades and materials to be installed individually over some number of weeks, IMPs are installed by a metal building contractor and allow the walls and roof to be completely closed in with a single trade. The use of concealed fasteners in the side joint of the panels makes installation quick and easy. Unlike other construction systems, the inherent strength and resiliency of IMPs means that work doesn’t need to stop over weather concerns. All of this saves a considerable amount of labor costs and can also save a lot of time meaning buildings can be completed quicker and more economically. It could also mean that an owner is able to occupy and use the building sooner, thus reducing construction financing costs and allowing operations to begin more quickly.
Versatility for Use in Many Building Types
IMPs can be used in virtually any type of new construction and for many retrofit applications too. There is a range of modular panel sizes that can work successfully with different structural elements of the rest of the building. The finished profiles and colors can all be selected to match the design needs of the building with edges, corners, and trim details all based on simple, appealing aesthetics. There are even IMPs specially designed for cold storage or refrigerated space applications. These panels may be part of the building exterior or create an isolated space within a larger building. Either way, they are designed for the rigors of a high use installation.
With such a broad range of benefits and capabilities, you owe it to yourself to check them out for a building project that you may be involved in. The best place to start is by contacting your local MBCI representative, and by signing up for our newsletter to subscribe to our blog.
Appropriate Standing Seam Clips for Roof Panels
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:
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
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.
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.
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.
What You Need to Know About Insulated Metal Panels
Insulated metal panels (IMPs) are “lightweight, composite exterior wall and roof panels with metal skins and an insulating foam core” as defined by the Metal Construction Association (MCA). The outer skin serves as either metal wall siding or metal roofing using standard profiles, while the inner face serves as a metal interior finish or liner. The rigid insulation between the metal skins gives the panels their superior energy conservation properties and also provides a rigid core for extensive spanning capabilities across structural members.
With this basic make-up in mind, here are a few things you should know about using IMPs in a metal building project:
Virtually any building being designed as a metal building should consider the use of IMPs. This includes all types of commercial, industrial, institutional, recreational and government buildings. More specifically, IMPs have been used very successfully on manufacturing facilities, schools, retail centers, offices, warehouses, power plants and many other building types.
Insulated Roofing and Walls Assemblies
IMPs serve as a complete wall or roof assembly. That means they can provide cladding, insulation, a water-resistant barrier, an air barrier, and finished surfaces all in one panelized product – essentially everything but the building structure upon which they are installed. These characteristics are true for conventional buildings as well as for specialty construction types such as the climate controlled processing, storage, or distribution of perishable food or other items. With panel thicknesses commonly available from 3 inches to 6 inches, walls and roofs can be designed to meet the specific thermal performance requirements of virtually any building need.
IMPs are available in a wide variety of colors, widths, profiles and finishes, enabling virtually any aesthetic desired for walls and roofs. Further, architectural IMPs provide the freedom to address building-specific or unique circumstances with options such as custom shapes and widths, special custom colors and finishes, custom fabrication including, but not limited to bent corners, curved panels, and trimless ends. Architectural IMPs also offer options to integrate with windows, louvers, sunshades or other similar products to offer total building envelope solutions.
Most IMPs are fabricated with the intention of working together as a complete system. That means attention has been paid to the design of the edges so the panels can interlock and be sealed to form a continuous joint that is water tight and air tight. In some cases panels may need to overlap, such as on long roof runs over 50 feet, but manufacturers have worked out those details to help assure the roof or wall performs as intended. Based on this, properly-installed IMP systems generally come with a very long warranty period.
Ease of Installation
The fact that IMPs are a single, finished, rigid panel, makes them quicker to install than other multi-product and multi-step assemblies. This translates to obvious labor savings and some material cost savings compared to other systems. Further, the simplified installation process has been shown to limit exposure to accidents, helping create a safer, more efficient work flow. It can also mean that construction time schedules are easier to meet or even beat.
To find out more about IMPs and ways to use their full characteristics and capabilities on a building you are working on, contact your local MBCI representative.
Sealing the Deal: The Importance of Properly Sealing the Building Envelope Using IMPs and Single-Skin Panels
The primary purpose of a building’s envelope (roof and walls) is to protect the building’s interior spaces from the exterior environment and provide the desired exterior aesthetics. Whether choosing insulated metal panels (IMPs) for their superior performance or, instead, looking to the wide range of aesthetic choices available with single-skin panels—or some combination of the two—the common goal must always be to protect the building from the potential ravages of water, air, vapor, and thermal/heat. By ensuring proper installation of metal panels and, thereby, properly sealing the building envelope, problems can be mitigated, efficiencies maximized, and the integrity of the building protected.
Here, we’ll briefly consider the benefits of each panel, and some key considerations relative to their sealant needs and capabilities.
Insulated Metal Panels (IMPs)
IMPs are lightweight, composite exterior wall and roof panels that have metal skins and an insulating foam core. They have superior insulating properties, excellent spanning capabilities, and shorter installation time and cost savings due to the all-in-one insulation and cladding. In effect, IMPs serve as an all-in-one air and water barrier, and are an excellent option for retrofits and new construction. With their continuous insulation, roof and wall IMPs provide performance and durability, as well as many aesthetic benefits.
Generally speaking, because of the nature of the joinery, it is easier to get a good seal in place with IMPs given their relative simplicity (i.e., putting the two pieces together with the sealant). They require great attention, though, in terms of air and vapor sealing—aspects largely controlled by the installers on a given project. As an example, vapor sealing in cold climates or applications is critical to the overall soundness of a building. Consider the damage a building could incur if moisture seeps into a panel and becomes trapped; it if freezes, it could push panels out of alignment. This would result in not just an unattractive aesthetic, but a performance failure as well. In order to be effective, all sealant and caulking must be fully continuous.
Single-skin panels, alternatively, offer the advantage of an expansive array of colors, textures and profiles. They are also thought to have more “sophisticated” aesthetics than IMPs. Single-skin panels are available in both concealed fastener and exposed fastener varieties, and are part of an assembly. They can be used alone or in combination with IMPs, and as long as the needed insulation is incorporated, single-skin panels can meet technical and code requirements, depending on the application. Single-skin products offer a wide range of metal roof systems and wall systems as well.
Getting the proper seal on single-skin panels may require extra sealants or closures, and have more parts and pieces that have to come together to create the seal. However, when properly installed and sealed, they can provide excellent performance in their own right. Some key caveats include ensuring panel laps are properly sealed with either tape or gun butyl sealants, and carefully inspecting air and water barriers for proper installation as well as penetrations through the wall for sealing/fire caulking prior to panel.
In most cases, following the details for the most common conditions will give you a successful and high-performing outcome.
Regardless of the type of metal panel used, taking the time and effort to ensure the sealing and caulking details are properly handled, metal buildings can protect the built environment and provide long-lasting quality and performance.