ORN THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO   ONTARIO ROOFING NEWS – WINTER 2017  11 warranty. Therefore, periodic main- tenance often may be required for accessories and all other materials that interact with the roof system. For instance, open pitch pans (metal boxes applied around supports) typically need to be refilled every two to three years. The fill material dissipates over time, and movement from the supports creates openings. Roof coatings, depending on their grade, may require maintenance ev- ery three to five years. Areas of maintenance can also be found at intersections of differ- ent building components or mate- rials, particularly where sealants are applied. Sealants require periodic maintenance because they have an average service life span of five to seven years. These areas experi- ence differential movement of the materials, and openings and splits commonly occur. Points such as separate elevations, adjoining walls, and joints at metal terminations and skylights are all maintenance items. RoofDesignforMaintenance To effectively control roof maintenance, there must be an un- derstanding of the design aspects of repair and reroofing specifica- tions, which may ultimately impact maintenance requirements. This paper is intended to provide best practices to assist designers of no/ low maintenance roof systems at each component. The degree of maintenance re- quired for any roof is often deter- mined at the time of its construc- tion, whether it be the original installation or at reroofing. The need for maintenance can be unwittingly “built in” to the original roof system by certain elements of the design. Some of these design elements can be corrected during repair or re- roofing; others will continue to be constant maintenance items. It is necessary for those charged with the design of roof systems to become familiar with the effect of mainte- nance requirements of the system and strive to design a low-mainte- nance system. In new construction, a designer has more control over the building configuration, such as wall heights, perimeter treatments, and slope and drainage facilities, all of which can be designed in an optimum fashion. In addition, the designer will also have a larger selection of membrane systems to choose from, further giving them control over the design of the roof. When existing construction requires reroofing, a designer is faced with modifying pre-existing conditions to maintain technically sound treatment approaches, a de- sign task often more difficult than new construction design. After its original construction, a roof, in addition to aging and weathering, may undergo other changes. A new drain may be installed to improve drainage, a roof-mounted HVAC unit may need replacement, or entire areas may need repair or re- roofing. The manner in which such activities are conducted may dras- tically impact maintenance. Such modifications are often attempted without design guidelines and by individuals not familiar with, or unconcerned with, the technical efficiency of their activity. When designing a roof system, the emphasis begins at the roof deck and continues up through the mem- brane surfacing. Each component of the roof must be carefully integrated to ensure complete compatibility throughout the system. It is the roof designer’s job to develop a system of many separate components that, once assembled, will serve as a single system. The designer should also provide design that eliminates ex- tensive maintenance requirements. The roof system that is designed in this manner will provide a long wa- terproofing service life. The typical roof system compo- nents are as follows: •  Underlayment (depends on deck type) •  Insulation System • Membrane • Surfacing • Flashings •  Metal Terminations • Accessories Insulation Insulation serves two primary functions in a roof system. It pro- vides thermal resistance and a sub- strate for the roofing system. Insula- tion can also be used to create slope for positive drainage. All of these functions are critical to the success of the system. The most important function of insulation is to provide thermal re- sistance. This is an economic asset to the building owner, as it prevents heat loss and reduces energy (heat- ing and cooling) costs. Insulation’s heat flow resistance is measured by its thermal resistance, which is known as R-value, and increases with the thickness of the insulation. In addition to providing thermal resistance, insulation also reduces deck component temperatures, which reduces expansion and con- traction. This is an important char- acteristic that can prevent premature roof failures due to membrane splits. Insulation also serves as a sub- strate and may increase the strength of the roof system. Insulation, es- pecially applied over a metal deck, provides a firm base to which the membrane is to be adhered. The insulation should have the com- pressive strength to enable it to re- sist normal traffic loads and most weather elements. Insulation with a high compressive strength will help to prevent the breakdown of both the insulation and the membrane. It will also increase the membrane’s re- sistancetopunctures,whichwilllead to a longer service life of the system. A best design practice for roofs that will experience heavy and/or consis- tent traffic is to specify an insulation high density cover board. Roof insulation can also be used to create an artificial slope on a roof with the application of a tapered insulation system. Tapered insula- tion systems are primarily used on reroofing applications where the initial deck construction was not applied with sufficient slope. It can also be used on new construc- tion where slope is not built into the structure. This should eliminate ponding water, which occurs after a rainfall when proper slope is not present. Positive slope has a substan- tial impact on roof system longevity and maintenance requirements. The proper design elements for insulation are as follows: •  Insulation must be kept dry; wet insulation should be re- moved and replaced; •  No more insulation shall be ap- plied than can be covered the same day; •  Insulation boards shall be butt- ed and aligned; •  Secure insulation to the sub- strate with fastening or adhesive patterns to meet the specific building requirements; •  Ensure that board joints are supported on metal decks; and •  When installing multiple lay- ers of insulation all joints shall be staggered. Membrane The roof membrane is the wa- terproofing component of the roof system. Most designers base the roof system design on the selection of the membrane. The manufac- turer, the warranty, and application methods are all determined during this design phase. If the designer is to provide the owner with a no/low-maintenance type roof system, the membrane selection must be completed by review- ing the potential site-specific re- quirements that may occur over the life span of the roof system. For instance, membrane selec- tion will be different if the owner plans on staying in the facil- ity over the life span (15 to 20+ years) of the roof as opposed to selling or vacating the building after a shorter duration. Membrane selection is typi- cally determined by building use and the required durability of the membrane. The designer should be aware of the anticipated level of traffic. Durable membranes are required on roofs that will experience heavy foot traffic; some large manufacturing facili- ties may require protection from motorized vehicles or carts, as opposed to buildings where roof access is minimal. Some determining factors are types, sizes and amount of required rooftop equipment be- cause more equipment means more traffic and more poten- tial problems (roof leaks). The other determining factor regard- ing rooftop equipment is future modification. Buildings with constant tenant change – such as offices, restaurants and shops – may require continual changes (additions and deletions) of roof- top equipment. This will have an impact on membrane mainte- nance, validation of the warran- ty, and life span of the system. Two ways to prevent roof-traffic damage include: Walkway Pads. The best de- sign practice to eliminate con- cerns of traffic is to install walk- way pads over the completed membrane surface. The walkway pads should be applied in all heavy-traffic areas, at entrances and ladders. They should also be applied around all service- able mechanical units to guard against dropped tools. The grade of the pads should be determined based on the extent of traffic. In extreme cases, steel walkways are recommended instead of wooden walkways, which can deterio- rate over time and may require