Corrosion Issues in Roofing Systems Knowledge Area  

by Joseph C. Dean, P.E., and Steve Geusic, P.E., Lean-Miguel San Pedro Powers, NAVFAC EXWC, for Director, Corrosion Policy and Oversight (DCPO) (DASD (Materiel Readiness))

Updated: 01-28-2022

Introduction

"Corrosion" is most often associated with "rust" and the oxidation of other metals; 10 U.S.C. § 2228 defines corrosion as, "the deterioration of a material or its properties due to a reaction of that material with its chemical environment." It is inclusive of the deterioration of all materials, which can be caused through sun exposure (ultraviolet [UV] radiation and heat), moisture, mold, mildew, wind, and other environmental factors.

The term "weathering" is often used to describe roofing materials and roof condition and is used in several criteria documents. "Weathering" is "the process of wearing or being worn by long exposure to the atmosphere", which is very similar to the definition of corrosion. Merriam-Webster defines it as "the action of the weather conditions in altering the color, texture, composition, or form of exposed objects." Words related to "weathering" include depletion, depreciation, erosion, ablation, attrition, consumption, and dissipation. These words also can be associated with corrosion and appear in some of the articles discussing roofing deterioration. When UV, heat, temperature, and moisture are considered, "weathering" clearly describes the erosion (corrosion) of roofing materials.

Roofs and roofing systems corrosion and can be summarized as follows (see the Facilities Corrosion Impacts on Operations and Missions Table  which provides awareness into how facility categories can be affected by corrosion):

• Corrosion Deterioration Description: Material degradation (asphalt binder breakdown), loss of flexibility, cracking of roofing materials
• Factors Contributing to Corrosion: Humidity, rain, condensation, erosive forces, UV exposure (see Photo 1), heat, snow loads, freeze thaw actions, hail damage
• Operations and Mission: Barrier failure endangering structural integrity and interior safety (mold, mildew, water damage/flooding)

This Knowledge Page will focus on describing the corrosion and weathering risks in roofing systems, both new and existing.

Description

Facilities depend upon well-functioning roofing systems to prevent rainfall, wind, and snow/ice melt and moisture from invading interior spaces. Multiple roofing design types include asphalt shingles (typically found on residential properties), metal, built-up, and single ply membranes. The Roofing Systems information resource, which is part of the Whole Building Design Guide (WBDG) Building Envelope Design Guide, provides an excellent description of various roofing system types, composition, and associated issues. Roof structures must be designed to support the roof deadload as well as the roofing system and dynamic loads such as wind, snow, seismic, and rooftop equipment. For instance, if a roofing design includes the use of parapet walls, careful attention is needed to ensure that all moisture including rain and snow are fully and efficiently removed from the roof and building envelope through well-functioning roof drains, valleys, gutters and downspouts. When these components fail, water may pond on the roof creating additional load stress to the roof structure.

Roofs are located in a variety of different environments, each with their own unique challenges related to material degradation and corrosion. Roofs located in coastal zones, with their inherently higher Environmental Severity Classification (ESC), will likely experience higher levels of corrosive deterioration. In these varied and ever-changing environments, designers and maintainers must be vigilant to ensure that the best materials, construction processes and sustainment practices are utilized consistent with that ESC Zone. A facility's roofing design must be selected with life-cycle effectiveness and durability considerations to ensure that it meets the required availability for the operating forces and mission accomplishment.

The Corrosion Prevention and Control (CPC) that is related to the planning and design of roofs for facilities and supporting structures requires a thorough understanding of the many aspects of the area where they are to be installed and the associated unique design characteristics driven by the local Environmental Severity Classification (ESC). See also Unified Facilities Criteria (UFC) 1-200-01 DoD Building Code. Factors ato consider in the planning, design, construction, and sustainment of roofs include:

• Environmental Severity Classification (ESC)
• Sun exposure (ultraviolet [UV] radiation)
• Saltwater effects on materials and structures (depending on the proximity of the roof to saltwater and the coastal environment)
• Pressure sources (e.g., earthquakes, winds, snow loads; see Photo 2)
• Friction and material interactions, including the prevention of corrosion arising from dissimilar metals and incompatible materials
• Correct application and use of paints and coatings
• Ponding risks that can affect materials, interior spaces, and structural integrity (water accumulation without the ability to efficiently drain away from the roof structure and building envelope)
• Design geometry to prevent unnecessary corrosion situations (e.g., roof valleys allowing water access to building interiors, parapet walls, internal downspouts, dissimilar metal interaction, and failure to provide proper barriers and insulation between corrosive materials)
• Selection of materials and coatings to achieve the required life-cycle and service requirements
• Prevailing weather (rainfall amounts, hail, snow, wind)
• Proper design and installation of flashing at roof transitions, penetrations, and termination points.

Weathering of Roofing Materials—An Overview, by Berdahl et al., submitted to Construction and Building Materials, February 2006, is an excellent summary of environmental and chemical effects on roofs and roofing materials. It explains:

• The "degradation of materials initiated by ultraviolet radiation" causes changes in "plastics used in roofing, as well as wood and asphalt."

• "Elevated temperatures accelerate many deleterious chemical reactions and hasten diffusion of material components."

• "Effects of moisture include decay of wood, acceleration of corrosion of metals, staining of clay, and freeze-thaw damage."

• "Soiling of roofing materials causes objectionable stains and reduces the solar reflectance of reflective materials causing the roof to become a sunlight absorber accelerating roof materials degradation. (Soiling of non-reflective materials can also increase solar reflectance.) Soiling can be attributed to biological growth (e.g., cyanobacteria, fungi, algae), deposits of organic and mineral particles, and to the accumulation of fly ash, hydrocarbons and soot from combustion."

• Even the most durable of materials are modified by deposits of dust and debris and may encourage the growth of biological organisms, a condition often seen on residential roofs.

• "Temperature rise in sunlight can directly lead to materials degradation. Increased temperature can accelerate deleterious chemical reactions, cause loss of volatile constituents, and soften some polymers. Temperature changes, either gradual or sudden (rain shower on a hot day), cause stresses due to differential thermal expansion."

• Energetic "photons can break many chemical bonds, especially in organic materials. For example, plastics, wood and asphalt are all organic materials composed largely of carbon and hydrogen atoms linked into chains, rings, and more complex structures. Most such materials are altered by ultraviolet radiation, usually followed by oxidation."

• Wind can cause vibrations in roofing materials that result in material fatigue and cracking.

• Hail can be extremely damaging to roof materials. Moisture in all of its forms cause risks to building materials and, the building interior, when failures occur.

Weathering of Roofing Materials—An Overview, by Berdahl et al., also provides excellent insights into photodegradation (UV) exposure to polymeric and other organic materials, including explanations of the associated processes. Polymer coatings utilized in metal roofing coatings (polyester, silicone-modified polyester, and PVDF [polyvinylidene fluoride]) are discussed including the chalking (surface erosion) that occurs. Ceramic tiles, if free from reactive and water-soluble impurities, are very durable. Polymeric materials have greater flexibility and elasticity which helps in resisting tearing. Cold temperatures have the opposite effects on elasticity and can cause brittle failure. Moisture imposes an important negative result in the degradation process. Each of these materials and the atmospheric affects upon them are important in that when a designer selects a roofing material, it needs to be compatible with the environmental stresses that exist in the locale where the roof will be required to function.

The WBDG page Integrity Testing for Roofing and Waterproofing Membranes provides information on determining the extent of moisture intrusion through a roof, including explaining the different types of testing, limitations, and conditions, such as multiple roof penetrations, inexperienced technicians, and overburden in place, which affect testing results. Testing is best performed immediately after installation. The Residential Building Enclosure page discusses, in the "Roofing" section, the construction of valleys, dormers, chimneys, parallel roofs, eaves, gutters and downspouts to mitigate corrosion risk. Proper flashing to waterproof these roof transitions is critical. This short treatise on location and construction of these features extends to commercial structures as well. It emphasizes cleaning and locating these features.

Roof slopes play an important role in roof effectiveness and may present design challenges. Rain elimination through guttering and downspouts are a key design feature of a successful roof installation. Locations of gutters, valleys, downspouts, and the use of parapet walls can mean the difference between a dry interior and one that causes damage to the structure within. The maintenance of roofing throughout the life cycle can be a huge cost factor, especially if the roof has been poorly installed or designed. Roofing materials affect life cycle costs as well.

Preventing moisture intrusion (e.g., via leaks, humidity, condensation) is an essential function of the roof. Accomplishing that goal has been problematic over the years and served to challenge roof designers, manufacturers, contractors and facility managers. Ensuring that the condensation process is effectively managed will reduce the amount of corrosion. Here are some factors that will help reduce the intrusion of moisture into the building envelope:

• Installing snow and frost barriers
• Installing appropriately sized, located and installed guttering
• Inspecting and cleaning valleys, gutters and downspouts in a timely manner
• Minimizing the use of parapet walls
• Ensuring that parapet walls, if they are used, are well-designed to be able to be routinely cleared of debris
• Minimizing the use of interior down spouts; ensuring that they are well-maintained
• Conforming to good engineering practice for nail patterns and attachments
• Using fasteners that are consistent with the material type to ensure that dissimilar metal corrosion is prevented
• Ensuring construction quality that is consistent with the contracted design
• Ensuring the roofing design is appropriate for the environmental factors associated with that region (weather, wind, and precipitation)
• Considering, monitoring and correcting deficiencies associated with weathering, corrosion, UV, and heat
• Minimizing foot traffic over roof areas that can possibly cause damage to membranes
• Inspecting and correcting roofing undersides for possible leaks (see Photo 3)
• Minimizing roof penetrations to support roof-mounted equipment (these must be inspected and fully resealed over time, not just at construction turnover; see Photo 4)
• Designing and constructing well-constructed valleys
• Considering and addressing wind uplift in the roof design and construction
• Using light-colored roofing materials where possible to reduce heat and UV changes
• Ensure that rooftop mechanical equipment discharge, particularly condensate water, is piped directly into roof drains. Continuous condensate leaks can damage the roof membrane.

Environmental Severity Classifications (ESC) for the Department of Defense (DoD) are described in UFC 1-200-01 DoD Building Code and further described in the ESC CPC Resource Page. The Corrosion Prevention and Control (CPC) efforts to keep facilities located in ESC Zones 4 and 5 operationally ready are challenging and require sound planning, design, construction, and sustainment efforts commensurate with those conditions.

Specific corrosion references from the Roofing Systems information resource include (see Photo 5):

• "Exposed asphalt is susceptible to ultra-violet degradation, therefore, built up roofs (BUR) are surfaced with aggregate, a field-applied coating or a mineral surface cap sheet. Coatings include aluminum-pigmented asphalt, asphalt emulsion (reflective or non-reflective), urethane, and acrylic."

• "Atactic polypropylene (APP) membranes are generally resistant to high-temperature flow. To avoid surface cracking from ultra-violet radiation, a field-applied coating (such as aluminum-pigmented asphalt, asphalt emulsion, or acrylic) may be applied."

• "A protective surfacing is required for long-term performance of a Sprayed Polyurethane Foam (SPF) roof system. A protective coating must serve multiple functions in protecting the underlying SPF and should be selected from coatings that have been specifically designed for SPF and have a proven history of performance when used over SPF. Protective surfacings are a part of SPF roof systems to provide weatherproofing, ultraviolet (UV) protection, mechanical damage protection, and fire resistance." The top coating tends to deteriorate and fail before the foam and needs to be re-applied periodically.

• "Of the deck types used today, steel is the most common. Although prime-painted steel decks with welded connections are commonly specified, it is recommended that galvanized decks be specified in order to obtain greater corrosion protection in the event of roof leakage. It is also recommended that screw, pneumatic, or powder actuated-attachment be specified in lieu of welding, because screws provide more reliable attachment. Refer to the NRCA's Industry Issue Update, Moisture in Lightweight Structural Concrete Roof Decks."

• "For corrosion protection on steel panels, current practice is to specify 55% aluminum-zinc alloy. Until the late 1990s, unpainted aluminum-zinc alloy panels had a factory-applied lubricant to facilitate roll forming. The lubricant eventually weathers away, but installation smudges and fingerprints result in uneven appearance for a while. A thin clear acrylic coat can be specified to provide a more even appearance and show the effects of weathering more gradually, as the acrylic weathers away. Acrylic-coated Galvalume is sold under trade names such as Galvalume Plus and Acrylume."

Many DoD facilities are maintained by contracts. To ensure acceptable life-cycle results, these roofing contracts must include strong quality assurance (QA) and quality control (QC) programs. Contracts such as Design-Build, in which contractors hire architects and engineers of record, must include criteria that will identify material selection guidance by ESC Zone. See also the CPC Acquisition Issues Resource Page.

UFC 1-200-01 DoD Building Code provides very specific guidance for design, construction and sustainment actions related to CPC, especially in corrosion-prone locations. Corrosion-prone locations as defined in the UFC require a higher level of protection. Some of these areas apply to roofing systems as follows:

• Exterior exposed metallic elements at a location with an ESC of C3, C4, or C5.
• Exterior exposed nonmetallic elements at a location with an ESC of C4 or C5.
• Locations where microenvironmental factors (for example, prevailing winds, ventilation, waterfront environments, industrial emissions, deicing salt application, possible chemical splash/spillage, adverse weather events such as flooding or wind-driven rain, and penetrations of the building envelope) may create a locally corrosive environment regardless of ESC.
• Humid locations identified in ANSI/ASHRAE/IES 90.1 as climate zones 0A, 1A, 2A, 3A, 3C, 4C, and 5C.

By thoroughly understanding corrosion-prone location factors and their effects on materials and system performance, facility owners can achieve longer life cycles for their facilities. The UFC 1-200-01 Appendix ESC for DoD Locations, identifies the ESC Zone for each of the DoD installations around the world, which then drives the selection of the types of materials and processes that should be used for corrosion-prone locations. The UFC requires the use of "materials that are resistant to, or protected from, ultraviolet radiation. High ultraviolet exposure results in rapid deterioration of most nonmetallic roof materials, paints, sealants, elastomeric coatings, and wood." Products should be designed "to prevent corrosion in applications where elevated temperatures are present. Elevated temperatures have adverse effects on building materials such as paints, woods, and many asphalt-based products. High temperatures combined with high humidity cause severe deterioration."

The CPC highlights from several of the most relevant Unified Facilities Criteria (UFC) and Unified Facilities Guide Specifications (UFGS) documents for roofing systems are provided below:

• UFC 3-101-01 Architecture discusses vapor barriers, moisture, and similar building envelope requirements to ensure a dry interior. The basis of design for a roof system selection must include the construction of the roof, membrane selection, substrate, slope, drainage system, and justification for the use of parapets. Design drawings must include roof penetration details, surface termination and transitions, roof ridges, roof edges, and parapet and drainage details. This UFC also discusses sealing air leaks.

• UFC 3-190-06 Protective Coatings and Paints provides requirements and technical guidance for the effective use of paint-type coatings to protect common materials such as metal, concrete, pavements, gypsum board and wooden structures at military activities from deterioration. It requires paints and coatings that are durable and minimize the need for preventative and corrective maintenance over the expected service life of the component or system. It emphasizes the importance of ensuring that roofs are intact and functioning, with no leaks, prior to coating areas. Different materials shall be used based on local environmental conditions (see UFC 1-200-01 DoD Building Code as required in the UFC). Corrosive environments, which require additional corrosion protection, are those project locations that have an Environmental Severity Classification (ESC) of C3, C4 or C5. Humid locations are those in ASHRAE climate zones 0A, 1A, 2A, 3A, 3C, 4C, and 5C, as identified in ASHRAE 90.1. This UFC also defines coating systems for specific uses. The term "weathered" and "weather events" are mentioned and address surface treatment requirements. Repairing water-associated problems, such as deteriorated roofs and nonfunctioning drainage systems, is required prior to application of coatings. See Photo 1 for an example of the UV degradation of an organic coating system.

• UFC 3-110-03 Roofing describes the multiple roofing types, materials, roofer qualifications and sustainment options. The UFC must be used in conjunction with the current editions of the National Roofing Contractors Association (NRCA) Roofing Manuals (NRCA Manual), the NRCA technical bulletins, and the Metal Building Manufacturers Association (MBMA) Metal Roofing Systems Design Manual (MBMA Roofing Manual) to provide specific design guidance for military roofing projects. This UFC explains how to apply the NRCA Manual and the MBMA Roofing Manual to the design of military projects and the associated limitations and restrictions. Additional guidance includes:

  • Satisfactory roofing performance comes from careful system and material selection, design, contract document preparation, specification, installation, and maintenance.
  • Roofing systems are exposed to the full brunt of the weather and can allow moisture intrusion or fail prematurely if not properly designed, installed, and maintained.
  • Moisture intrusion can be costly, adversely impacts the functions within the building, and result in roof system failure. Since modern roofing systems contain considerable thermal insulation, moisture intrusion lowers thermal efficiency and hinders energy conservation.
  • Wet materials support fungus or mildew, cause deterioration of other roofing system components, and can emit odors leading to sick buildings and occupants.
  • Factors to consider include weathering, corrosion, ultraviolet radiation, durability, and life cycle.
  • The roof design must incorporate systems and details to meet environmental corrosivity conditions for the specific project location, as defined by Environmental Severity Classification (ESC) (See UFC 1-200-01 for ESC designations for DoD worldwide locations and the International Organization for Standardization [ISO] Corrosion Category Estimation Tool [ICCET]).
  • The humidity conditions must be considered during roof design; humid locations are those in ASHRAE climate zones 0A, 1A, 2A, 3A, 3C, 4C, and 5C, as identified in ASHRAE 90.1.
  • The UFC addresses the use of protective metal coatings, types of steel and aluminum and influenced by ESC Zone.
  • Roof asset management with the use of the DoD Sustainment Management System—BUILDER™ and Roofer™ SMS modules, is discussed.
  • The UFC discusses maintenance and the associated inspections required for the creation and sustainment of an effective sustainment program, as well as identifying, locating and addressing leaks.
  • According to the UFC, for roofs larger than 15,000 square feet or are classified as "critical use" or "mission critical", a registered roofing consultant (RRC), registered professional engineer (PE), or registered architect is required on the design team.

• UFC 4-440-01 Warehouses and Storage Facilities delineates design requirements for the roof structure and associated components and discusses corrosive-climatic-resistant finishes.

• UFC 4-750-07 Recreational Aquatic Facilities addresses moisture management for roofs, dew-point analysis, and structures to eliminate excess moisture and heat. Facility systems are to be moisture- and corrosion-resistant. Exposed metal surfaces must be coated appropriately to resist the corrosive environment within. It should be understood that corrosive chemicals in the moisture will affect the underside of the roof structure causing erosion of the metal surfaces and staining of ceilings; see photos 3 and 6. It states that "deterioration of materials from condensation should be anticipated and minimized with mechanical design and construction material selection resistant to chemical corrosion from the pool atmosphere."

• UFGS 07 32 14 Clay Tile Roofing Replacement or Repair requires the use of corrosion-resistant fasteners and mentions UV protection in the context of elastomeric roofs. (Note that this UFGS is being revised and combined with another UFGS. At the time of this posting, the newly revised UFGS had not been posted.)

• UFGS 07 41 13 Metal Roof Panels discusses considerations for corrosion protection from chemical and UV radiation including primers, factory finishes, abrasion resistance, and surface protection from damage. It also discusses corrosion-resistant fasteners and miscellaneous metal framing, screws and rivets. ESC requirements for aluminum sheet metals is delineated as well as for sheet steel panels. Excessive weathering during the warranty period is mentioned.

• UFGS 07 41 63 Fabricated Roof Panel Assemblies discusses excessive weathering during the warranty period and includes corrosion-resistant fasteners and screws.

• UFGS 07 51 13 Built-Up Asphalt Roofing addresses weathering, corrosion-resistant materials and installations. UV is mentioned in the context of designing cool roofs.

• UFGS 07 52 00 Modified Bituminous Membrane Roofing mentions weathering, corrosion resistant materials and installations and addresses UV in the context of designing cool roofs.

• UFGS 07 53 23 Ethylene-Propylene-Diene-Monomer Roofing requires the use of UV-resistant polypropylene as recommended by the manufacturer, requires corrosion-resistant fasteners and stress plates, and uses terms such as weathering, cracks, splits, tears, and delaminates.

• UFGS 07 54 19 Polyvinyl Chloride Roofing uses terms such as weathering, cracks, splits, tears, and delaminates, requires corrosion-resistant fasteners and stress plates, and requires the use of UV-resistant polypropylene as recommended by the manufacturer.

• UFGS 07 55 00 Protected Membrane Roofing (PMR) discusses tests, design reviews, construction meetings, quality control plans, quality assurance requirements, and submittals. It addresses actions associated with the membrane to protect and ensure proper performance.

• UFGS 07 57 13 Sprayed Polyurethane Foam (SPF) mentions weathering.

• UFGS 07 61 14.00 20 Steel Standing Seam Roofing delineates corrosion resistant construction requirements for materials, warranties, closures and fasteners.

• UFGS 07 61 15.00 20 Aluminum Standing Seam Roofing mentions corrosion, warranty, rust, and weathering.

• UFGS 13 34 19 Metal Building Systems has extensive coverage of roofs, rust, corrosion and corrosion-resistant materials and references ESC requirements.

• UFGS 33 56 21.17 Single Wall Aboveground Fixed Roof Steel POL Storage Tank addresses corrosion and corrosive environments.

The criteria listed above are not necessarily all-inclusive, but it does contain some insights into the magnitude of the challenges associated with designing, constructing and sustaining roofs found in ESC Zones 1 through 5. Evaluating and addressing these issues will assist in achieving a corrosion-resistant design that supports mission effectiveness and meets life-cycle expectations.

Non-Government Standards and UFC 3-110-03

UFC 3-110-03 Roofing describes the relationship between the National Roofing Contractors Association (NRCA) Roofing Manuals (NRCA Manual), the NRCA technical bulletins, and the Metal Building Manufacturers Association (MBMA) Metal Roofing Systems Design Manual (MBMA Roofing Manual). UFC 3-110-03 explains how to apply the specific design guidance for military roofing projects from the NRCA Manual and the MBMA Roofing Manual. The Sheet Metal and Air Conditioning Contractor's National Association (SMACNA) Architectural Sheet Metal Manual is to be used for technical information, specifications, and drawings related to replacement of sheet metal components. The Spray Polyurethane Foam Alliance (SPFA) document SPFA-127 Maintenance Manual for Spray Polyurethane Foam Roof Systems should also be followed.

Sustainment

CPC plays a significant role in installation facility Sustainment, Restoration and Modernization (SRM) and Operations and Maintenance (O&M) of DoD installations. SRM and O&M are complimentary efforts that leverage good engineering practice and requirement identification to ensure that the CPC program is robust and consistent with ensuring that each installation and its facilities are operationally ready. To determine the best course of action, it is essential to determine the cause and rate of corrosion.

There are numerous types of M&R methods for roofs, which include patching, crack sealing, surface treatments, roof-section replacement, roof cleaning, gutter and valley cleaning and repair, and surface recoating where appropriate. Mesh Reinforced Elastomeric Coating (MREC) is an effective roof sustainment strategy. Applying MREC when a roof has begun to degrade but still functions by 10–15 or more if done repeatedly, and avoid costly roof replacements. Keeping an accurate asset database and an associated condition summary facilitates timely M&R actions that will keep the roof in good operating condition and queued up for timely repairs or replacement. See Figures 1 and 2 for sustainment program flowcharts and considerations.

Figure 2 illustrates the Sustainment process and the associated work flow. Identifying and tracking roofing deficiencies through this process will ensure that the necessary work will be scheduled and accomplished in a timely process.

UFC 3-110-03 states: "Roof management involves an asset management approach, taking into account performance measures, periodic inspections, routine maintenance and repair, and correct application of quality roofing products." Creating and leveraging a roof-system database will help with tracking and scheduling roof actions, planning, replacement actions, and understanding and evaluating life cycle cost attributes. Using the BUILDER™ and Roofer™ SMS modules provides for creating a database, assessment and maintenance management of roofing assets. The Facilitiesnet.com article Roof Coatings Protect Against UV Light, Leaks, Corrosion, by Jeffrey J. Opel, discusses the importance of having an "aggressive" roof maintenance program that includes ensuring that roof coatings are kept intact and functioning well to extend the life cycle. Maintenance program steps are described such as items to inspect, frequency of walk-overs, and power washing of dirty areas (see Photos 7 and 8).

UFC 3-110-03 Roofing requires that all roofs (on the installation) be inspected at least once annually. NRCA recommends "twice annually inspection after storm events like high winds, hail, heavy rain, or snow accumulation." Housekeeping functions (gutter clearing, sealant replacement, along with inspections to identify further required actions) are required. Inspections should include attention to the condition of flashing (skylights, perimeters, walls, penetrations, equipment curbs, drains), condition of roof surfaces and junctions, and areas of weakness.

UFC 3-110-03 Roofing provides guidance on various approaches to roof sustainment. Re-roofing options, re-covering, elastomeric coatings, metal roof overbuilds, and roof replacement are discussed along with life-cycle considerations and the associated expected longevity. Installation of a new vapor barrier, retarder, air barrier or insulation is required. Wet insulation must be replaced. Per the UFC, "New slope built-up metal roofs will have a minimum of 2 inches (50 mm) of fiberglass batt insulation and continuous sealed vapor barrier installed directly underneath the roof panels to prevent corrosion from condensation." Recommendations for ASHRAE climate zones 4 and 5 are included. Identifying and locating leaks are discussed. Actions are described to ensure that roofs awaiting replacement or repair are functioning to ensure the elimination of moisture within the building envelope.

This UFC has an Appendix discussing roofing best practices and topics such as sustainability, long-term performance, improving roof thermal efficiency, and responsible use of materials. Factors contributing to corrosion control are mentioned, such as reduction of roof penetrations, providing effective drainage to avoid ponding, selecting appropriate roof color and texture, controlling roof access to prevent damage and punctures, and adopting preventive maintenance, including periodically inspecting roofs and implementing timely repairs. The UFC also discusses locating membrane breaches and addresses routine maintenance activities, such as keeping gutters and downspouts clear and providing design features such as downspout strainers and cleanouts.

For more insights into CPC sustainment management, see the CPC in Operations and Maintenance (O&M), and, Sustainment, Restoration, and Modernization (SRM) resource page, which provides additional information on the DoD SMS and BUILDER™, and CPC data collection.

Summary

These factors must be considered and addressed to ensure that a roof will meet life cycle requirements:

• Area weather and environmental severity
• Specific roofs that work well for the location and the building mission and function
• Material and corrosion science (effects of corrosive forces on materials)
• Building construction practices that will either impair or improve roofing performance
• Influence of UV, moisture, heat, wind, rain, hail, snow, biological organisms, and pollution on roofing materials and installations
• Roofing systems that address the risk factors associated with the area to be installed
• A sustainment program that includes roof inspections, penetration assessments, timely repairs, and interior inspections and testing for moisture intrusion
• A roof replacement plan (see Photos 9 and 10)
• A Sustainment Management System (SMS)

Controlling and managing corrosion and weathering of roofing assets to ensure building envelope integrity is a complex effort, made more successful with the use of a roofing sustainment management system (SMS) like BUILDER™ and the Roofer™ module. While some actions may not seem directly related to CPC, a properly functioning roof is, in fact, a corrosion-resistant membrane. If kept intact and maintained, then each element will serve to prevent corrosion and protect the building such that it can safely meet mission and operational objectives.

Additional Resources

Department of Defense—Whole Building Design Guide

Unified Facilities Criteria (UFC)

• UFC 1-200-01 DoD Building Code
• UFC 1-300-02 UFGS Format Standard
• UFC 3-101-01 Architecture
• UFC 3-190-06 Protective Coatings and Paints
• UFC 3-110-03 Roofing
• UFC 4-440-01 Warehouse and Storage Facilities
• UFC 4-750-07 Recreational Aquatic Facilities

Unified Facilities Guide Specifications (UFGS)

• UFGS 07 32 14 Clay Tile Roofing Replacement Or Repair
• UFGS 07 41 13 Metal Roof Panels
• UFGS 07 41 13.16 Copper Roof Panels
• UFGS 07 41 63 Fabricated Roof Panel Assemblies
• UFGS 07 51 13 Built-Up Asphalt Roofing
• UFGS 07 54 19 Polyvinyl Chloride Roofing
• UFGS 07 53 23 Ethylene-Propylene-Diene-Monomer Roofing
• UFGS 07 55 00 Protected Membrane Roofing (PMR)
• UFGS 07 57 13 Sprayed Polyurethane Foam (SPF)
• UFGS 07 61 14.00 20 Steel Standing Seam Roofing
• UFGS 07 61 15.00 20 Aluminum Standing Seam Roofing
• UFGS 09 97 13.27 High Performance Coating for Steel Structures
• UFGS 13 34 19 Metal Building Systems
• UFGS 33 56 21.17 Single Wall Aboveground Fixed Roof Steel POL Storage Tank

Whole Building Design Guide (WBDG) Resources

• CPC Source—Corrosion Science Knowledge Area
• CPC Source—Paints and Coatings Knowledge Area
• CPC Source—Environmental Severity Classification (ESC)
• CPC Source—Facilities Corrosion Impacts on Operations and Mission 
• CPC Source—CPC in Operations and Maintenance (O&M), and, Sustainment, Restoration, and Modernization (SRM)
• Roofing Systems
• Aviation
• CPC—Acquisition Issues Resource Page
• Warehouse
• Integrity Testing for Roofing and Waterproofing Membranes
• Residential Building Enclosure

Whole Building Design Guide (WBDG) Tools

• Corrosion Toolbox (ICCET)
• CPC Checklists Tool

Training

• CPC Source—Training
• Corrosion Fundamentals
• Coating Fundamentals

DoD Installations Organizations

• Office of the Deputy Assistant Secretary of Defense (Construction)
• Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL)
• Air Force Civil Engineer Center (AFCEC)
• Naval Facilities Engineering and Expeditionary Warfare Center (NAVFAC EXWC)

Organizations / Associations

• ICC IBC International Building Code
• Metal Building Manufacturers Association (MBMA)
• Sheet Metal and Air Conditioning Contractor's National Association (SMACNA)
• The National Association of Roofing Contractors (NRCA)
• Spray Polyurethane Foam Alliance (SPFA)

Publications

• Demonstration of The Corrosion-Resistant Sustainable Roofing Systems, CERL Final Report for DCPO Project F08-AR02, June 2013.
• Metal Roofing Systems Performance Guide Specification , MBMA, January 2012.
• Weathering of Roofing Materials—An Overview . Berdahl, Akbari, Levinson, Miller, Construction and Building Materials, February 2006.
• Roof Coatings Protect Against UV Light, Leaks, Corrosion, by Jeffrey J. Opel, FacilitiesNet.com