Tile roofs provide a bold aesthetic appeal like no other roof system. Combined with tile’s natural insulation properties and lifelong protection from the elements, it’s no wonder that they are the system of choice for discerning customers who want to combine beauty, prestige, protection and, ultimately, value to cover their home or professional building.
Most professional roofing contractors are creatures of habit: applying the skills and knowledge gained from previous experience to choose the components for each new roof tile assembly. However, we must also remember that each project – its location, neighborhood constraints, potential hazards, budget and more – is unique and requires our ingenuity as we design the system.
A roofing contractor can design roof systems? Yes. Designing a roof system best suited to each project falls under the scope of a Florida-licensed roofing contractor. In order to design systems that will meet code requirements, match customer expectations and perform well during Florida’s common high wind events, licensed contractors must be careful to pay attention to the array of options available, choosing components that play well together and are code-approved.
Since the statewide enforcement of the initial Florida Building Code (FBC) in March 2002, South Florida (Miami-Dade and Broward counties) has maintained its own version of the code in that region, which is referred to as the High Velocity Hurricane Zone (HVHZ). The HVHZ code is often perceived as being more robust and providing greater protection to its residents. However, recent articles in Florida Roofing (see Florida May Have a Flaw in its Roofing Code Armor, May 2021 and FRSA Tile Underlayment Testing Confirms Concerns, October 2021) have questioned the appropriateness of such a perception, specifically in response to Miami-Dade officials’ ongoing exclusion of a tile roof system that uses a direct to deck, self-adhered tile underlayment that offers the highest wind uplift resistance values and a proven secondary water barrier. This system is permitted in the rest of the state, but not in the HVHZ. FRSA continues to hope that South Florida officials will “see the light” and permit its citizens this option but, as of now, they remain entrenched against the system.
For the rest of this article, I will use “standard FBC region” to refer to the code applicable in 65 counties throughout Florida (but not in the HVHZ) and “HVHZ” to refer to the code enforced in Miami-Dade and Broward counties. Keep in mind that both of these regions fall under the Florida Building Code.
In the 65 counties included in the standard FBC region, the Florida Building Commission has adopted the FRSA-TRI Florida High Wind Concrete and Clay Tile Installation Manual, currently in its sixth edition, as a reference standard. This manual provides a flowchart to guide a roofing professional who is designing a roof tile assembly. It also includes a series of tables that allow the contractor to find ASCE 7 values depending on mean roof height, exposure category, roof slope, roof zone and local wind speed requirements that are needed for the flow chart. The roof tile system will include an underlayment system, metal flashing and attachment options.
Step 1: Underlayment System – The first step is to determine if you are going to use:
1. Two-ply hot mop underlayment with a mechanically- attached anchor (or base) sheet. This is a prescriptive method. If you choose this option, you will need to follow the methods spelled out in the tile manual for the system that matches the specifications (mean roof height, exposure category, etc.) of the roof assembly that you are designing. Or,
2. Direct to deck or other underlayment system. These assemblies require a Florida Product Approval and include the self-adhered direct to deck system that currently offers the highest resistance to uplift. As noted previously, these systems are permitted in the standard FBC region, but are not an option in the HVHZ.
Step 2: Metal Flashing – Depending upon whether or not you will be using battens, which are optional in
the standard FBC region, you will select metal flashings either with returns (when using battens) or metal flashings without returns (when battens are not being used).
Step 3: Tile Attachment – Finally, tile attachment options include either mechanical fasteners or an approved roof tile adhesive. There are also product approvals that combine mechanical fasteners and roof tile adhesive. These hybrid systems allow contractors
to design a system with higher uplift resistance values.
For Miami-Dade and Broward counties, a roofing professional’s choices for a roof tile assembly are spelled out in roofing application standards (RAS). This method is also available as an option in most Florida municipalities outside the HVHZ. The standards include
RAS 127, 118, 119 and 120. The roof tile system will include an anchor sheet and underlayment, metal flashing and attachment options.
Step 1: Anchor Sheet – The anchor sheet will be an ASTM D226 Type II (30#) sheet. The nailing pattern requires one row at the lap 6” o.c. and, in the field, two rows staggered at 12” o.c.
Step 2: Underlayment – There are two options available:
1. A “two-ply hot mop,” which traditionally refers to a 30/90 hot mop but has been expanded to include certain modified granule-surfaced membranes that are also usually applied in hot asphalt.
Or,
2. An approved self-adhered tile underlayment product that is applied over the asphaltic surface of the ASTM D226 anchor sheet.
Step 3: Metal Flashing Options – Similar to the standard FBC region specifications, the HVHZ has options for metal flashings either with or without returns depending upon whether or not battens are being used. Unlike the rest of the state, however, the HVHZ does require battens for roofs with a higher pitch (see RAS 118 and 119). For lower-pitched roofs, battens are optional.
Step 4: Tile Attachment – Like the standard FBC region, HVHZ has options for mechanically fastened, roof tile adhesive and, for systems that require higher uplift resistance values, hybrid systems.
Installation parameters, product approvals and Miami-Dade notices of acceptance (NOA) have been established to help contractors design systems using compatible components. When properly applied to each unique project, the resulting roof tile assemblies
will perform well during high wind events such as hurricanes and other storms. They will also handle the day-to-day demands of the Florida sun, high relative humidity and other environmental challenges: all while providing a beautiful roof that adds value and vigilantly protects its residents. FRSA member roof tile manufacturers, who are all also TRI members, are ready to help you navigate the design process with a knowledge of approved roof assemblies and real-world feedback from the roofing professionals they support.
Manuel “ Manny” Oyola, Jr., Eagle Roofing Products, holds a roofing contractor’s license and is an active member of the Tile Roofing Industry Alliance (TRI) and the Palm Beach County Roofing & Sheet Metal Contractors Association, his local FRSA Affiliate. He is also an active member of FRSA’s Codes Committee and Codes Subcommittee, serves as the Secretary- Treasurer on FRSA’s Executive Committee and participates on the FRSA-TRI Manual Reformatting Committee. Manny teaches roof tile courses for TRI
and FRSA.
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