Ballasted Roofs – A New Look at an Old System
November 6, 2019
While ballasted roof systems aren't as popular today as they used to be, they are still being installed successfully across the country.
  
Stone-ballasted roof systems began appearing sometime in the early 1970s. While they appear superficially similar to built-up roofing (BUR), there are major differences between the two systems. Both are topped with rocks, but BUR uses a thin layer of pea gravel or crushed stone no larger than a quarter-inch diameter partially embedded into the asphalt topcoat to protect it from the sun's UV rays. In a ballasted roof, the stones are much larger - at least an inch in diameter - and applied much more heavily. In fact, the weight of the stone ballast is what holds the roof components in place. The weight can vary from 10 pounds per square foot (the minimum allowed by code) to 25 pounds or more. The most common ballasted assembly was a loose-laid EPDM membrane over a rigid insulation board.

By the 1980s, designers were integrating concrete pavers into ballasted roof designs, creating access paths, pedestrian walkways, and even rooftop plazas. When the green building movement came along in the late 1990s, it was natural to transition the ballast from stone to soil, creating vegetated or "green" roofs.

Ballasted roofs are loose-laid; this means the contractor can assemble all the components, including the roofing membrane and insulation, without fastening them to each other or the roof deck. Membrane seams are sealed, of course, and the waterproofing layer is secured to the parapet and at roof penetrations, but it isn't adhered to the roof deck or the layers beneath it.

By eliminating nearly all the adhesives and fasteners other assemblies require, ballasted roofs typically cost less and are quicker to install than other systems. EPDM is popular because it can be ordered in large sheet sizes, which minimizes seaming. TPO and PVC are also popular as single-ply roofing membranes under ballast.

For designers, ballasted roofs provide a natural-looking surface that blends well with a range of architectural styles. With paver-ballasted designs, the roof can become a plaza, patio, or other usable outdoor space suitable for recreation, walking, or relaxation.

 For the building owner, ballasted roofs are durable and long lasting. Stones or concrete pavers protect the waterproofing layer from UV rays, hail, and foot traffic. If repairs are needed, the loose-laid layers are easily taken up. And at the end of the roof's designed lifespan, the lack of adhesives ensures the membrane will be fully recyclable.

Advantages

Economy: Ballasted roofs use economical materials and are among the fastest to install. In fact, they have one of the lowest lifecycle costs of any roofing system on the market today.

Scheduling:
These roofs can be installed in a wide range of weather and temperature conditions, and close in the building envelope faster than most other systems. For occupied buildings, there are no offensive smells associated with the install.

Aesthetics:
Ballast can vary from large round cobblestones to pavers. This natural look is appealing to many building owners and architects. Rock can be combined with pavers to provide a variety of textures and utilitarian purposes.

Amenity Space:
With proper planning, ballasted roofs are suitable for plaza decks, walking paths, recreation areas, and other uses.

Energy Efficiency:
Ballasted roofs reduce heating and cooling loads. A system with a weight of 17 pounds per square foot saves as much energy as an ENERGY STAR-rated reflective roof.

Fireproof:
Stone and concrete are virtually fireproof, so ballasted roofs provide the highest fire rating available. Class-A fire resistance can be achieved without gypsum board underlayments or expensive fire-retardant chemicals.

Durable:
The stone or concrete pavers also provide protection from UV rays, hail, foot traffic, and extreme temperature fluctuations.

Ease of Repair:
Removal and re-installation of the ballast and insulation is easy, and both can be reused. No adhesives or fasteners are used, so it's easy to separate the components. Even in a complete replacement of the waterproofing membrane, the ballast stone or concrete pavers can be reinstalled.

Recyclable:
Most of the components are reusable and/or recyclable. Rocks, pavers, and rigid insulation board can be reused. The unadhered membrane is easy to remove and recycle.

Stormwater Management:
Green roofs and other options like Carlisle's Stormwater Retention Option can retain as much as 65% of the rainwater that falls during a storm. This can help owners and developers reduce fees.

 Consult the EPDM Specification on the Carlisle SynTec Website here or consult the Ballasted Stormwater Retention Brochure here or contact Craig Tyler at Craig.Tyler@CarlisleCCM.com for further questions.
March 4, 2020
ENERGY STAR Roofing Program Phaseout

The ENERGY STAR® Roofing Program will be phased out by June 1, 2022 The U.S. Environmental Protection Agency (EPA) has announced they are sunsetting the ENERGY STAR reflective roof program effective June 1, 2022. Program Partners must cease production of printed or electronic marketing material using the ENERGY STAR mark by June 1, 2021. All references to ENERGY STAR must cease by June 1, 2022. As a leader in the commercial roofing industry and the largest manufacturer of reflective and non-reflective roofing materials, Carlisle Construction Materials supports this change, as it eliminates one source of confusion regarding energy efficient roof design. As a rule of thumb for energy efficiency, reflective roofs are best suited for cooling-dominated climates where buildings' air conditioning demands or costs exceed their heating demands – typically, southern markets in ASHRAE Zones 1, 2, and parts of 3. In heating-dominated climates, a non-reflective roof covering is ideal to reduce heating costs (and the burning of fossil fuels) as well to as mitigate the risk of condensation-related issues within the roofing assembly. Carlisle continues to advocate for careful selection of complete roofing systems based on required performance attributes and considering the building's design, intended use, location, and climatic conditions. Additional Resources For more information on roof condensation, reference the November 2012 Design Advisory on how to avoid condensation issues from occupancy- or construction-generated moisture. November 2012 Design Advisory For more information on the condensation risks of cool roofs, check out this short animation. Condensation Risks of Cool Roofs For further reading, visit the Carlisle SynTec website for a white paper on Mechanically Attached Roof Systems in Cold Climate Zones. White Paper Contact Craig Tyler at Craig.Tyler@CarlisleCCM.com with questions.

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February 19, 2020
FM’s VSH Testing – Very Severe Hail

FM Global, a leading commercial building insurer, and its code-approved testing agency subsidiary, FM Approvals, have created a Very Severe Hail (VSH) impact resistance classification that could affect design professionals. FM Global Guidelines Traditionally, FM Global has recommended its insured building owners use moderate hail (MH) and severe hail (SH) classified roof systems for buildings located in areas FM Global considers to be susceptible to moderate or severe hail impacts. FM Loss Prevention Data Sheet 1-34 ("Hail Damage") provides a map identifying these regions. In recent years, the insurance industry in the United States has seen an uptick in losses from hail in terms of the number of claims experienced and costs of those claims. A majority of the hail damage occurs to roof systems and other rooftop components. In the latest version of FM 1-34 (April 2019), FM Global identified a new VSH region encompassing Oklahoma, Kansas, Nebraska, South Dakota, most of Texas, and parts of Montana, North Dakota, Minnesota, Iowa, Missouri, Arkansas, Wyoming, Colorado, and New Mexico.  Per FM Global, this area was classified as a VSH region based on data from the National Oceanic and Atmospheric Administration's National Weather Service and National Center for Environmental Protection's Storm Prediction Center. This data shows a concentration of reports of hail greater than 2 inches in diameter in this geographical region. Until recently, FM Approvals did not have VSH-classified roof systems available to satisfy its recommendation in the VSH region. In the interim, FM 1-34 recommended using assemblies tested to a Class 4 rating using FM 4473 ("Specification Test Standard for Impact Resistance Testing of Rigid Roofing Materials by Impacting with Freezer Ice Balls"). FM 1-34 indicates aggregate- and paver-ballasted roof systems can be substituted for MH- and SH-classified roof systems in the MH and SH regions. However, FM Global restricts the use of aggregate-ballasted roof systems on buildings taller than 150 feet, or in areas where the design wind speed is 100 miles per hour or greater. FM has indicated only paver-surfaced roof systems can be substituted for a VSH-classified roof system. FM 1-34 also contains recommendations for skylights, rooftop HVAC equipment, and other critical outdoor equipment in the MH, SH, and VSH regions. Hail Classifications FM Approvals traditionally has tested and classified membrane roof systems for MH and SH impact resistances using FM 4470 ("Approval Standard for Single-Ply, Polymer-Modified Bitumen Sheet, Built-Up Roofs (BUR) and Liquid Applied Roof Assemblies for use in Class 1 and Noncombustible Roof Deck Construction). This is the same test method on which many FM Approvals roof system classifications are based. Using FM 4470's procedure, MH-classified roof systems withstand a 2-inch-diameter steel ball weighing 1.19 pounds dropped from a height of 81 inches in a section of tubing. This results in an impact energy of about 8 foot-pounds (ft-lbs.) on the surface of the roof system test specimen. SH-classified roof systems withstand the same 2-inch-diameter steel ball dropped from a height of 141.5 inches, resulting in an impact energy of about 14 ft-lbs. on the surface of the roof system test specimen. FM Approvals recently updated its impact-resistance test method to include testing for the VSH classification. The new testing involves propelling 2-inch-diameter preformed ice balls at roof system test specimens using an ice ball launcher. The ice balls are propelled at 152 to 160 feet per second, resulting in an impact energy of 53 to 58 ft-lbs. on the surface of the roof system test specimen. With these higher test standards, new materials and assemblies are being developed and tested to meet the new ratings. Carlisle has introduced a new coverboard, EcoStorm, that can achieve the VSH rating. Carlisle currently has 133 approved VSH approved assemblies. For more information on EcoStorm VSH Coverboard, click here. Contact Brian Emert at Brian.Emert@CarlisleCCM.com with further questions.

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February 5, 2020
Spray Foam for Walls – The Perfect Wall

The challenge with every design is making sure that it will work in a specific environment. Through understanding the principles of a "perfect wall" - one which contains a water-shedding layer, an air control layer, a vapor control layer, and a thermal control layer - we can generate a wall solution that will work in every environment. The control layers are listed in order of importance. All are important, but not equally important. The ranking comes from historic experience and the underlying physics. Controlling water in the liquid form (rain and ground water) has been the focus of architects for generations. Controlling air is a much more recent focus - less than a century. The corollary, however, is too often true for many in the industry. There should be no doubt, the water control layer is much more important than the air control layer. Controlling vapor is even more recent - only a generation or two. Air movement transports significantly more water in vapor form than does vapor diffusion and therefore air control is more important than the control of molecular water vapor. "Air barriers" are more important than "vapor barriers". Thermal control dates back millennia - but getting it wrong has rarely led to durability failures. The thermal control layer failures have been typically limited to comfort issues and operating cost issues. Hence, thermal control layers are listed last on the control layer "priority" list. In the last decade we have been successful at combining the water control layer, air control layer, and vapor control layer into a single layer that can be a film, coating, membrane, or sheet goods. We have also had good success with wrapping the exterior of a building with all of these control layers and then enclosing those control layers with the fourth control layer - the thermal control layer. This configuration, with the thermal control layer outboard of the water, air, and vapor control layers, allows the assembly to be constructed in all climate zones: cold, mixed, hot and humid, or dry. Even better, this configuration allows this assembly to enclose virtually all interior environments in all climate zones: offices, commercial, residential, institutional, pools, museums, art galleries, and data processing centers. The sole exception being refrigerated buildings and cold storage facilities. In such assemblies the location of the thermal control layer is "flipped" with the other control layers - the thermal control layer now becomes located on the interior of the other three control layers. Utilizing spray foam technology, you can create the "perfect wall" with spray polyurethane (SPF) which meets; Water Control Layer - SPF is inherently moisture resistant. Air Control Layer - SPF has an Air Impermeability of <0.02 (L/s/m2) @ 1 inch of mercury. Vapor Control Layer - SPF has a water vapor permeability of 1.4 perm @ 1 inch of mercury. Thermal Control Layer - SPF has an R-Value per inch of 6.9. This also allows for thinner walls and continuous insulation without thermal breaks. Visit the Carlisle Spray Foam Insulation website at carlislesfi.com for more information on how your next project could utilize spray foam insulation as a "perfect wall" solution. Contact Brian Emert at Brian.Emert@CarlisleCCM.com with further questions.

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