July 10, 2019

Design Wind Speed and Warranty Wind Speed

We’ve already discussed wind uplift design in a previous SpecTopics post (FM 1-90 vs. ASCE 7); this post will help you understand how those wind speed numbers relate to wind speed warranties.  To calculate wind uplift for a roofing project, you’ll need to determine the building type and local wind speed. In gathering this information, some designers look at the American Society of Civil Engineers’ ASCE 7 Wind Maps for their area, see a number like 90- or 120-mph, and think that is the wind speed their building will encounter. Therefore, they specify the same speed for their warranty (i.e. 120 mph local speed means I need a 120-mph wind speed warranty). Rest assured, this is not the case. ASCE 7 maps have contours with the local speeds in 10 mph increments. ASCE 7-2005 and ASCE 7-2010 were relatively straightforward; most of the U.S. was in a 90-mph zone. However, in 2016 ASCE deemed it necessary to have separate maps for each building risk category (Category I, II, III, and IV). This increased the wind speeds for most of the country, especially for projects with increased risk categories. Naturally, designers saw this increase and thought that since the local wind speed was increasing, they needed to ask for increased wind speed warranties. (i.e. 130 mph or more). Again, this is not the case. It’s true that warranted wind speed is the limit of 3-second peak gust recorded at the weather station nearest your building project, measured at 10 meters above the ground, during a weather event that affects your building project. But to achieve wind speeds over 90 mph, a cyclonic windstorm (tornado, hurricane, etc.) is generally necessary. If your building experiences a cyclonic windstorm, there will be flying debris, broken glazing, and other envelope breaches that could cause roof failure (over-pressurizing the building, detachment of decking from structural components, etc.). This would not be covered under a roofing warranty, regardless of the wind speed coverage. Keep in mind that a roofing warranty assumes that the building remains intact, the decking remains solid, the inside pressure of the building is generally equalized, and foot traffic is limited to maintenance and inspection of rooftop equipment. It is not building insurance. Like fires and vandalism, critical weather events such as tornadoes and hurricanes are covered by the building owner’s insurance carrier. Choose a warranted wind speed that makes sense for you and your client, but you don’t need to match that with your local wind speed. You’ll just be paying more for something you don’t need. Always verify your need for increased warranty wind speed before inquiring about matching your local wind speed with the warranty. Contact Craig Tyler at [email protected] with questions.

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June 26, 2019

Moisture in Concrete - Part 1

This post focuses on the moisture phenomenon in concrete and the difference between lightweight and normal-weight structural concrete. Curing versus drying and the standards used to determine relative humidity levels are also addressed. Part II will address design recommendations and roof assembly selection. Moisture in Newly Poured Structural Concrete Roof Decks When investigating roofs for leaks, invariably, moisture is found beneath the roof membrane. However, the source of moisture is not always a roof leak. Newly poured structural concrete could be a contributor to the presence of moisture beneath a new or a replacement roof. Concrete is a mixture of several components that reaches its optimum strength through a chemical reaction induced by water. Concrete needs water to allow for flowability and workability, however, water also has adverse effects. Once the concrete has cured, the remaining water is considered “free water”, or moisture which is no longer consumed by the curing process. Rain and snow add moisture to exposed concrete roof decks and further prolong the drying. As an example, a 4” slab of structural concrete contains as much as 200 gallons of free water per 1,000 square feet. ​Structural Concrete Mix Ratio The ratio for both normal-weight and lightweight structural concrete (LWSC) is generally the same: •10-15% cement •60-75% aggregate (fine and coarse) •15-20% water The difference is in the aggregate; the lightweight aggregate is pre-saturated prior to mixing. The lightweight aggregate, which is made up of shale, slate slag, or clay, can absorb 5-25% of its mass. Normal-weight structural concrete, however, utilizes aggregates such as sand and stone, which are not as porous and do not need to be wetted before adding to the mix. The popularity of LWSC is increasing due to: •Lower building structural cost; •Lesser density for reduced dead loads; and •Environmental and sustainability claims. Drying Time To reach a 75% relative humidity for normal-weight structural concrete, it will take approximately three months. However, achieving the same 75% relative humidity for LWSC will take twice as long. According to the Portland Cement Association, the dry-down time for LWSC is more than normal-weight structural concrete. Standards for Moisture Testing For many years, the roofing industry has used a curing time of 28 days after the concrete is poured. However, there are test methods published by ASTM for determining the moisture content in concrete. Qualitative tests, such as the plastic sheet test and electrical resistance and/or impedance are good indicators of the presence of moisture in a given area but are not as accurate as quantitative tests. Quantitative tests, such as the moisture vapor emission rate test, surface humidity, or in-situ relative humidity tests demonstrate levels of moisture present in the concrete. The recommended quantitative test is the in-situ relative humidity test (ASTM F2170), in which a sleeved probe is placed in a drilled hole in the concrete and left in place for 24 hours. After the 24 hours, an electronic reader is attached, and the information is read directly from the sensor. The relative humidity reading should be less than 80% at a depth of approximately 40% of the thickness of the slab. The moisture values and test duration stated above have been slightly modified to better suit outdoor roof conditions.  Site Considerations The concrete pour schedule can affect moisture testing and provide inaccurate moisture values. Therefore, in phased construction, the field testing and the roofing installation should be aligned with the concrete pour schedule and ICRI-Certified Concrete Inspectors should be commissioned. For in-depth information, the International Concrete Repair Institute (ICRI) offers various resources that can aid with the proper steps required for testing and evaluation. Stay tuned for part II for recommendations on design and the selection of an appropriate roofing assembly.

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May 29, 2019

Building Envelope Educational Courses, Tools, and Materials

The demand for high-performance building envelope systems is on the rise. Energy codes such as ASHRAE 90.1 and the IECC continue to increase requirements aimed at creating more energy efficient and environmentally friendly designs. Some of these increasing code requirements involve the addition of continuous air barriers, as well as continuous insulation to wrap the entire building. Architects, specification writers, and designers have the almost impossible task of staying up-to-date on new code requirements, understanding how and why changes were made, and accurately and appropriately incorporating these changes into their designs. Over the last several decades, Carlisle Construction Materials (CCM) has become the premier single-source supplier of building envelope materials, including single-ply roofing, air and vapor barriers, waterproofing membranes, insulation, metal products, and more. Therefore, CCM is focused on educating and assisting design professionals through training courses, as well as helpful tools and materials, to minimize the learning curve experienced by architects when code changes occur. Here’s some information on CCM’s newest educational courses, tools, and materials to help you stay at the forefront of building envelope designs. Education is paramount to the success of building envelope projects, which is why CCM offers free courses to design professionals on various building envelope design considerations. CCM’s “Pushing the Envelope: Going Beyond Conceptual Design” is a 300-level, AIA-accredited course that explores proper product selection, material performance characteristics, test procedures, and best practices as they relate to building envelope systems. It is available online as a self-guided course here or you can request a face-to-face presentation here. CCM’s newest course, “Building Envelope Design – Understanding Codes, Best Practices, and Tie-in Detailing”, is a 400-level, AIA-accredited course available exclusively as a face-to-face presentation. This course helps raise awareness of code requirements as they relate to building envelope components and systems, with a focus on the all-important tie-in detailing needed to provide an air tight building. Common material misconceptions are also discussed. For more information on CCM’s Building Envelope Design course, or to request an face-to-face presentation, click here.  As energy code requirements increase the need for air barriers and continuous insulation, questions about fire safety may arise. In most cases, the International Building Code (IBC) requires compliance with NFPA 285, which is the Standard Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components. Carlisle Coatings and Waterproofing (CCW) offers both an online tool and mobile app that allow you to build an NFPA 285-approved assembly. When finished, a submittal document is created for the wall you designed, and this document can be provided to your building code official if your design is ever called into question. To build your NFPA 285 wall assembly, click here or download the app by searching “NFPA Guide” on the AppStore, GooglePlay, and Amazon. Since continuous air barriers became a requirement of energy codes, building designers have been given the difficult task of determining material compatibility and proper tie-in sequencing of dissimilar systems. CCM’s breadth of building envelope materials allows for the internal vetting of material compatibility, taking away the guesswork typically required from designers. CCM’s NVELOP details are easy to read and understand, illustrating the most common material combinations along with step-by-step installation instructions to create the continuous air seal required by energy codes. NVELOP details can be downloaded from the NVELOP website here. CCM is unique in its ability to provide a wide range of materials from a single source. Similarly, NVELOP is unique in its ability to provide a single-source warranty for the tie-ins between dissimilar CCM systems. However, the uniqueness of CCM and NVELOP can make specifying for public bid projects complicated. To address these difficulties, CCM developed the MasterFormat Specification Sell Sheet with instructions on how to write CCM and NVELOP as the basis of design in public bid project specifications, while keeping them open for competition. To download CCM’s NVELOP MasterFormat Specification Sell Sheet, click here. NVELOP is unique in its ability to provide warranty coverage for tie-ins between dissimilar CCM materials. Traditionally, applying for and receiving a warranty for tie-ins was either impossible or extremely difficult and involved lots of paperwork and time. NVELOP eliminates these issues with an easy online warranty application process. Once the individual CCM system warranties are purchased and received, visit NVELOP’s warranty application portal here and fill in the appropriate information. If you have questions about any of these building envelope tools, please contact Chris Kann at [email protected]

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May 15, 2019

FM 1-90 vs. ASCE 7

Wind uplift design for roofing can seem daunting to the uninitiated. But with a little help from online tools, it can be much more straightforward. Wind uplift is calculated for all buildings using formulas, tables, and wind maps developed by the American Society of Civil Engineers (ASCE) in their publication ASCE 7-2016. With a project’s location, building use/occupancy, building height, and roof plan, there are a number of online tools you can use to determine the wind uplift required for your building. The calculator used by the National Roofing Contractors Association (NRCA) can be found at http://www.roofwinddesigner.com/. Once the uplift pressures for your building are determined, you must choose a design for your building that meets these pressures. Roofing manufacturers list their system designs through the DORA Directory of Roof Assemblies https://www.dora-directory.com/ or through Factory Mutual Global’s RoofNav® https://www.roofnav.com/Account/Login. The DORA Directory lists roofing assemblies based on uplift testing that various manufacturers have received through third-party verification, while FM’s RoofNav lists roofing assemblies that have been tested through FM Global’s own testing facility. Roofing assemblies that meet the minimum uplift requirements per ASCE 7-16 will meet the International Building Code (IBC); however, FM Global ratings may require additional enhancements based on their own calculations. The more stringent guidelines are due to the fact that FM Global is an insurance company and they approve designs before they issue coverage for a particular building. While FM 1-90 is a rating used by FM Global-insured buildings as a standard for their insurance coverage, the calculation of wind load for a particular building using ASCE 7 calculations is the basis for designing a roof meeting the IBC for all buildings, whether or not they are insured by FM Global. Meeting the standard for FM 1-90 will result in higher pressures in the perimeter and corners than using the ASCE 7 method, thereby increasing the cost of the construction of the roof. Changing these requirements at a later date or finding out your project does not require FM ratings may cause confusion during the bidding process and could result in higher bids. Always verify your need for FM Global before proceeding with wind load design. Contact Craig Tyler at [email protected] with questions.

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May 1, 2019

Misconceptions About Permeance in Wall Air Barriers

In moderate climate regions, and especially in southern states, specifiers are often tasked with selecting an air barrier that is vapor permeable. In many cases, they are advised by product manufacturers’ reps that products with a higher perm rating will deliver better performance. Various manufacturers have used this tactic to drive the sale of their products and limit competition. To counter this misleading marketing technique, it is imperative to understand permeance, how it relates to vapor retarder classification, and what it all means in terms of building performance.  Permeance indicates the rate of water vapor transmission through a material and is dependent on the material’s thickness, much like R-value in heat transmission. Permeance is often abbreviated to “perm”, which is the unit of measure used for vapor retarder classifications. A material’s perm rating is also what is needed when comparing the water vapor transmission of different building products.  The table below shows vapor retarder classification as accepted by the International Building Code (IBC). It is important to note that the less permeable a material is, the greater its resistance to water vapor transmission. Classification Definition Permeance I Vapor Impermeable Greater than or equal to 0.1 perm II Vapor Semi-Impermeable Greater than 0.1 perm but less than or equal to 1.0 perm III Vapor Semi-Permeable Greater than 1.0 perm but less than or equal to 10 perms Vapor Permeable Greater than 10 perms As the table above illustrates, any material with a perm rating greater than 10 is classified as PERMEABLE. Selecting a product solely because it has a higher perm rating than the definition of permeable doesn’t add any meaningful benefits to the performance of the system. The most important thing to consider when comparing perm ratings of various products is the test in which the perm rating was determined. ASTM E96 is the Standard Test Method for Water Vapor Transmission of Materials. ASTM E96 contains two test methods to determine the perm rating of materials: Method A (the desiccant method) and Method B (the water method). Results from these two test methods vary considerably and cannot be compared in any way. Therefore, it is extremely important when comparing and choosing a vapor permeable or vapor impermeable air barrier that the results are from the same ASTM E96 test method. Method B is the most commonly used for classifying materials due to the higher results it yields, representing a worst-case situation with an excess presence of moisture. Please contact Chris Kann at [email protected] with questions.

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April 17, 2019

Do Building Codes Require Structural Enhancement for Re-roofing Work?

Today’s re-roofing market is going strong, making up 62% of all roofing work versus 38% for new construction. While most specifiers and roofers know the requirements for re-roofing to meet current building and energy codes, there is always a level of uncertainty when it comes to the structure of the roof itself. Can I tear off the old roof and start my new roof application with the existing deck? Or is something more required? Re-roofing work consisting of a complete tear-off is considered an Alteration – Level 1 for the International Existing Building Code (IEBC) 2015 and 2018 editions. In Chapter 5, an Alteration – Level 1 is described as, “includes the removal and replacement or the covering of existing materials, elements, equipment, or fixtures using new materials, elements, equipment, or fixtures that serve the same purpose”. Descriptions of the code requirements for Alteration – Level 1 are in Chapter 7 and include Section 707 – Structural, which describes two additional structural requirements for roof replacement: 1.(707.3.1) Where the re-roofing work is more than 25% of the roof area, and the building is assigned a seismic design category of D, E, or F (Chapter 20 of ASCE 7), unreinforced masonry wall parapets must be braced according to 301.1.4.2 of the International Building Code (IBC). 2.(707.3.2) If the existing roofing system is removed and the deck is exposed for more than 50% of the roof area and the building is located where the ultimate design wind speed is greater than 115 mph OR the project is located in a special wind region, all structural roof connections must be evaluated for the wind uplift, and if unable to support 75% of the wind load, they must be strengthened or replaced as defined in Chapter 16 of the IBC. These requirements will not affect all buildings. Checking with a structural engineer to determine the existing building’s seismic design category or evaluating wind uplift potential of existing structural components will increase the project’s cost. Additionally, more costs could be added if structural remediation is required. Always check with the Authority Having Jurisdiction (AHJ) for local requirements before proceeding with re-roofing work. Contact Craig Tyler at [email protected] with questions.

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April 3, 2019

A New Trend in Building Envelope Specifications

With the ever-increasing emphasis on airtightness in commercial buildings, many of today’s building envelope projects are taking an approach similar to that of the roofing industry, where products are sourced from and warranted by a single company. Traditionally, building envelope projects have used products supplied by multiple manufacturers for use in below-grade waterproofing, walls, and roofing systems. This poses several concerns for architects and designers, including product compatibility, system performance, and liability. Similar concerns are what led the roofing industry to shift to a single-source, “system” approach in the late 1980s. Today, most roofing systems are single source. These systems utilize materials designed to work together from the start, allowing suppliers to offer extended and unique warranty coverage and eliminate finger-pointing in the event of a leak. One of the biggest advantages of a single-source building envelope is the ability to avoid product incompatibility at tie-in junctions, which can lead to air barrier breaches. With its NVELOP Building Envelope Solutions program and wide breadth of manufacturing capabilities, Carlisle Construction Materials (CCM) is leading the way in the movement toward single-source building envelope systems. CCM’s NVELOP is the industry’s most comprehensive single-source building envelope solution, featuring a variety of waterproofing, wall, and roof system materials. NVELOP's ability to ensure the compatibility of dissimilar materials eliminates the guesswork architects have conventionally dealt with when designing a building envelope system, while still allowing for design flexibility. The program’s tie-in detail suite provides vetted tie-in options that have been tested for durability, compatibility, and constructability. Additionally, NVELOP’s unique single-source tie-in warranty, available for up to 15 years, significantly limits architect and specifier liability and provides peace of mind to the building owner. For more information, visit the NVELOP website at www.carlislenvelop.com. If you have questions, please contact Chris Kann at [email protected]

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March 20, 2019

Tectum Inc. Voluntarily De-Listed from the FM RoofNav Website

Carlisle Construction Materials (CCM) has learned that Tectum Inc. has voluntarily de-listed their decking products from the FM RoofNav site. Tectum Inc. produces structural acoustical roof decks made of wood fiber cement which absorb sound and are compatible with a wide variety of insulation and roofing materials. CCM’s roofing systems are compatible with Tectum decks and share many RoofNav-approved assemblies. Because of the de-listing by Tectum, the FM Approvals for wood fiber cement decks and all related RoofNav listings have been removed from the FM approval site for all roofing manufacturers, not just CCM. Consequently, all wood fiber cement deck ratings listed in Carlisle’s State of Florida Evaluation Reports have been added to the SPRI DORA (Directory of Roof Assemblies) listing website. These ratings will still be applicable and can be specified when using the SPRI DORA directory in lieu of specifying FM approved roof assemblies. Many specifiers use FM approval ratings as a general guide for design, but may be specifying them on buildings which are not insured by FM Global. When specifying for building projects that are not FM insured, the specifier may use SPRI DORA assemblies or UL assemblies. The SPRI DORA listing is a web application database of roof systems tested in accordance with standards referenced in Chapter 15 of the International Building Code (IBC). This service lists wind uplift load capacity on single-ply and modified bitumen roof systems. For more information on the listing, visit www.dora-directory.com or contact Brian Emert.     Brian Emert     Designer & Doc Dev Specialist     Design Services     [email protected]

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March 6, 2019

Welcome to SpecTopics!

Welcome to the first installment of SpecTopics, a bi-monthly blog about topics related to designing and specifying roofing and waterproofing systems using Carlisle’s products. Carlisle has been a recognized leader in the roofing industry for more than half a century, manufacturing high-performance EPDM, TPO, and PVC single-ply membranes. Carlisle also offers roof garden systems, a full line of polyiso and expanded polystyrene insulation, and a host of steep slope underlayments, duct sealants, adhesives, and hardware. In addition to roofing, Carlisle services the waterproofing, framing, and general construction industries. This blog-based format will allow us to answer the most frequently asked questions we receive from architects and specifiers, as well as to share technical information and industry news. Our goal is for SpecTopics to serve as a resource for roofing, waterproofing, and building envelope issues. The focus will be on industry-wide issues that affect building product specifications and code approvals for roofing and air and vapor barriers. In the next few installments, we’ll cover trends in building envelope specifications, FM 1-90 requirements versus ASCE 7 requirements, and code-related language regarding re-roofing. Stay tuned; another SpecTopic will be published in two weeks. Contact Brian Emert for further information.     Brian Emert     Designer & Doc Dev Specialist     Design Services     [email protected]

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