Tile Talk: Attention to Detail

Improving Roof Performance Through Call Outs

by Richard K Olson, president & technical director, Tile Roofing Industry Alliance

(Editor’s Note:  Richard K. Olson is president and technical director for the Tile Roofing Industry Alliance.   The association represents industry professionals involved in the manufacturing and installation of concrete and clay tile roofs in the United States and Canada, and works with national, state, and local building officials to develop installation techniques, codes, and standards for better roofing systems.   Olson can be reached at rolson@tileroofing.org.)

For steep slope roofing, it is important for a design professional to create specific itemized requirements and call outs in project plans.  This will require increased knowledge in materials and codes that pertain to the specific project location.  When confronted with uncertainty in aspects of the roof design, we often use the terminology of contractor to field adjust or contractor to field adjust in compliance with local building codes and best practices.  These two terms allow flexibility for the roofing professional to address issues and jobsite challenges that are not covered in call outs, or the exact information is not known.  

         As the tile roofing industry, we have seen some interesting uses of the field adjust that we have addressed over the years, which might be worth revisiting as specific call outs.

         The fastening of any roof cladding is prescribed by code and included in code issued installation guides by the manufacturer.  In our manuals we have reference resources for determining the proper selection and fastening requirements for meeting the code designated wind speeds.  These tables provide design aids for mean roof height, exposure, wind speed, and roofing tile application method.  We have seen when not called out by the design professional, the contractor will use the fastener that happens to be in their truck at the jobsite and then ask our producing members or industry for a get out of jail letter after installation.  As a rule, we will not be able to comment beyond the actual code minimums or requirements set by the local building officials.  This is true for the attachment of field, hip, and ridge attachments.  By providing specific call outs, it removes the potential lack of proper fastening on your project.

         The selection of underlayment is another job specific call out.  Field adjusting to alternatives that are not equal or better can lead to the loss of the secondary barrier to perform as designed.  We are seeing the increased use of synthetics as equivalent to organics.  The underlayment manufacturers code issued product approval needs to be reviewed for fit for use for the roofing system you are calling out. 

         The design professional should allow the roofing professional latitude in considering an upgraded system that can help increase the life cycle of the roofing assembly.  As an industry, we generally provide the basic minimum code requirements to help ensure that all installations have met at least the code minimum.  With numerous upgrades for radiant barriers, underlayment’s, and fastening options, the project plans should acknowledge such upgrades can be considered.  When the roofing profession makes such choices, a review for equivalency should be performed.  We have seen proposed upgrades that are not actual upgrades when code resources are reviewed. 

         Roof layout is one of those areas that often allows for field adjustment.  With the increase of more complex roof designs utilizing multiple roof levels and planes, there will be the need to field adjust to meet the dimensions encountered.  Proper roof coursing is an area that we encounter on a regular basis.  The ability to provide proper roof layout directions is important to achieve a fully functional and aesthetically looking final appearance.  Too often we will see coursing up a roof and then a catch up with a short course at the ridge.  This requires additional cutting of tiles in the highly visible short course.  With proper layout the entire roof plane can have the required minimum head lap and equal coursing. 

         Proper flashing provides the ability to move anticipated tributary water off a roof.  For our concrete and clay roofing tiles this can be achieved using a pan or step flashing that will either keep the water on the tile surface or daylight to the eave.  With complex roof designs, this can often require moving water from one plane to another, or steep slopes re-directing water downslope.  Field adjustments are often needed to meet the intent of the flashing requirements.  Valley metal configurations, height of metals, kickouts at the end of eaves where walls continue, and roof penetrations should be reviewed with the contractor for water flow design needs.  One area of particular focus should be the valley designs.  The use of increased multi ribbed metals can help increase the downslope path for the water.

         With steep slope applications there are numerous eave treatments that can achieve the desired effect and code requirements.  For concrete and clay tiles we have design considerations for direct deck, raised batten, and increased ventilation for cold and snow regions, or increased energy efficiency.  For raised fascias, the need for anti-ponding is required to avoid water being trapped behind the fascia.

         Roof penetrations come in many forms that require additional call outs to properly flash.  Chimneys, skylights, soil, and accessories will each have different flashing needs to either direct water through step flashing or transition via pan metals as the water travels downslope.

         Solar installations are becoming more common for new construction.  How to properly mount, install wiring and integrate into the roofing system while meeting the codes is challenging to the roof professional.  As the TRI Alliance, we continue to meet with the solar industry in identifying proper installations and flashing requirements when used with our roofing tiles, or the use of a drop deck area to reduce the height of the panel. 

         By adding additional callouts to address the above topics, we can help improve the quality and long-term performance of future roof installations.

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