THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN 12  ONTARIO ROOFING NEWS – WINTER 2017 Roof Design maintenance to resolve safety concerns from trip hazards. On roof systems with heavy equipment or motorized traffic, the traffic area should include an overlayment that will protect the insulation. Entry Points. Entry points to the roof system typically experi- ence heavier loads than other walkway locations. To eliminate membrane damage at these points, it is recommended that in addi- tion to a coverboard, membrane protection such as concrete pavers be used. Another building usage condi- tion that has an effect on roof sys- tems is chemical output or debris. Interior activity from restaurants or heavy industrial operations may dis- charge chemicals or byproduct de- bris on the roof membrane that will require maintenance/repair and/or replacement. Some membrane ma- terials are better suited for these con- ditions. For instance, PVC mem- branes are better suited to reduce damage from greases and oils that will be discharged through vents on restaurants or kitchen areas. On war- rantied systems, make certain that the manufacturer provides coverage for chemical and debris discharge present at the facility. Roof systems that will experience continual output due to interior op- erations require permanent design requirements to eliminate mem- brane deterioration in these areas. There are two common methods of dealing with discharge. Application of a discharge containment acces- sory, available from a number of sources, that is applied around the exhaust vent is recommended. Fil- ters used in these systems to collect contaminants require regular main- tenance. The other type of applica- tion is to apply an additional layer of membrane to match the system in discharge areas. This creates a sacrificial layer that, if it deteriorates over time, will not contribute to roof leaks. The key design elements for membranes are as follows: •  Comply with the manufactur- er’s requirements; •  Specify required adhesive ap- plication temperatures – most products on the market require ambient outside temperatures to be above 40 degrees °F; •  Specify adhesive coverage rates based on manufacturers re- quirements – too much or too little may lead to premature fail- ures and/or loss of adhesion; •  Specify material be applied in an even application; and •  All roll materials shall be set in a straight line. Surfacing The use of surfacing materials has changed significantly in the past de- cade. The old Built-up Roof Systems used aggregate to shield the bitu- men from ultraviolet exposure that would cause damage to the bitumen surface. Surfacing materials are now used to provide energy savings and comfort to building occupants. The most prevalent surfacing material is a light-colored coating material that reflects the sun’s heat from entering the interior of the building. In some areas, coating materials are now re- quired on roof membrane systems and must meet reflectivity and emis- sivity regulations. (Note: some light-colored mem- branes have the inherent ability to meet reflectivity and emissivity re- quirements without the use of sur- facing materials.) Properly applied coating materi- als can extend the service life of a membrane. However, similar to all materials, there are higher-grade and lower-grade coatings. The designer should evaluate the coating material and choose one that best suits the requirements of the building. Coatings are not maintenance- free materials. Over time they will degrade and require repair and/or replacement. Rapid deterioration occurs from heavy levels of airborne pollutants, extensive ponding of water, chemicals, and debris. The designer should inform the coating manufacturer if these conditions are prevalent at the building and discuss design options, such as use of primers, specific coating material to apply in these areas, and required coverage rates. Most coating manu- facturers offer material warranties that range from two to 10 years. Extended labour and performance warranties may also be available. Itshouldbenotedthatforreroof applications a moisture analysis of the existing roof system will be required. Coating materials should not be applied over moisture-laden systems because they do not thor- oughly cure and are susceptible to premature failure through blister- ing, peeling and displacement. The designer should comply with the manufacturer’s applica- tion rates and ambient tempera- ture constraints. The application rate and temperature have a direct impact on the performance of the coating. The theory that “more is better” does not apply in these ap- plications. Too much material will slow down the curing rate of the coating material and could lead to runoff if precipitation occurs prior to complete cure. Drainage A common cause of roof dete- rioration is from improperly de- signed drainage. Treatments that do not allow for rapid runoff of water will result in ponded conditions, which accelerate deterioration of the membrane or coating in the ponded areas. Improper drainage that leads to the continual presence of ponding water 48 to 72 hours af- ter a rainfall may also affect the roof warranty coverage. The designer must design the drainage system in accordance with applicable code and design require- ments. The following are some items to be considered: •  Determine if using primary (in- terior drains) or secondary (ex- terior, i.e. gutter, scupper) drain- age is necessary. •  Ensure adequate deck slope; per IBC code the minimum slope is ¼” per foot. •  Place drains at mid-span (low points). •  Forbestresults,drainsshouldbe installed to meet local codes as a minimum. Individual building construction may require more than the code minimum. •  In geographically complex buildings at least one drain is required in each area. •  Position more drains as required in areas where excessive penetra- tions impede flow. •  Drains should be installed per code requirements for building locations, but additional drains may be required where exces- sive penetrations impede flow. •  Taper the roof system to drain. •  Water should be off the roof in 48 to 72 hours after a rainfall If the deck slope is not suffi- cient, then artificial slope will be required. This is common on re- roof applications that were origi- nally designed for BUR systems and/or systems where the deck has settled over the years. Drainage design for low/no maintenance should include: •  Slope to drain structural design; •  Full tapered insulation system; and/or •  Tapered insulation saddles (or crickets) at drains and the back side of curbs. Tapered insulation increases in- sulation thickness and may not be practical in areas where flashing heights are at a minimum. In some cases new drains can be installed at the ponded areas to increase water flow off the roof. This can only be accomplished if there is access to the interior area for installation of new pipes. These elements will help to reduce ponding water, but some annual maintenance may still be required. The absence of ponding water will minimize debris collected on the roof; however, roof debris may still form from overhanging trees, chemicals, or byproduct discharge and debris. All of these contaminants could plug the roof drains and impede water flow. In severe instances, impeded wa- ter can back up and infiltrate the building. Therefore, all roof drains should be inspected (and cleaned) an average of two times a year to make certain there are no clogged drains. Inspections should take place in the spring to evaluate the effects of the winter and in the fall to prepare for the winter. Flashings,MetalTerminationsand Accessories Industry statistics indicate that the vast majority of roof leaks occur at flashings, metal terminations and accessories. Improper design, poor workmanship and need of mainte- nance are all contributing factors to active roof leaks in these areas. In addition, the materials applied in these areas may have life spans that are shorter than other roof system components, and these materials are typically not covered in the manu- facturer’s roof system warranty. These conditions are often unique to each building and the designer should place more emphasis in the design of these components by se- lecting no/low maintenance materi- als and details. However, designers often build maintenance require- ments into these locations rather than designing them out. Properly draining roofing sys- tems, redundant flashing details and minimizing penetrations are all design items that can eliminate de- pendency on products that are not designed to last as long as the roof system components. Flashings The flashing component is the most vulnerable part of any roof system because it is at the point where the horizontal roof deck and vertical surface join. It is also the intersection of two different materi- als, such as parapet walls. Flashings are also vulnerable because they are applied around all roof penetra- tions, such as skylights, mechanical equipment, exhaust vents, expan- sion joints and other areas where the membrane is terminated and interrupted. The primary purpose of the flashing component is to seal the membrane at all edges. The flashing material should have a life expectancy that meets or exceeds that of the membrane. This is an important characteristic because the flashing generally has to perform under more-severe condi- tions. In addition, the flashing ma- terial should be compatible with all adjoining materials and must have the capability and durability to last the lifetime of the roof system. It is well documented that most roof leaks occur at flashing loca- tions. The designer can eliminate most of these problems by follow- ing industry-recommended best practices. Flashings should be pro- vided with a minimum eight-inch height if possible, or otherwise de- tailed in a manner that keeps the top edge of the flashing out of the water line. Flashing installed at less than eight inches may place the flashing in the water line, inviting problems. Further, flashings that are inadequately attached at their top edge (due to lack of nailing) may slump below their counter flashing, allowing for direct access of water into the building. Comply with the manufacturer’s flashing requirements for material and application requirements. Flash- ing materials must be from the roof membrane manufacturer, especially when they are used for repair/main- tenance activities. Using a different manufacturer’s materials may affect the warranty and could create more long-term problems for the system. Implementing the following de- sign elements at the different types of flashing conditions can help cre- ate a no/low maintenance system: •  Parapet Walls, Expansion Joints and Area Dividers: Ex- tend flashing material over the top of the horizontal substrate and down the outside face, un- der the sheet metal capping, to protect interior elements from water that enters from sheet metal openings (joints, ends etc.) over time. Without added flashing material water could enter into the building. •  Counterflashings: Sheet metal counterflashings can be ap- plied as a termination to verti- cal flashings and are typically applied over the flashing ma- terial at walls and curbs. A termination bar (1/8” x 1”) is typically secured near the top of the flashing material to hold it in place and eliminate slippage.