Manny Oyola, Jr, Eagle Roofing Products, Technical Manager Eastern Region/FL
Wood battens have been used for many years. Lately their use in roof tile installations in Florida is becoming more popular. Battens raise the tile off the roof and create additional air space. The resulting increase in air flow under the tile can provide a significant energy cost reduction. However, due to concerns about wind uplift, there are a few additional considerations that come into play in Florida.
The roof tile industry worked hand-in-hand with the FRSA to develop the FRSA-TRI Florida High Wind Concrete and Clay Tile Installation Manual, Revised 5th Edition. The wind tables in the manual provide uplift resistance values for the mechanical fastening options, screws or ring shanked nails.
When battens are fastened to the roof sheathing, they become part of the roof deck for fastening purposes. This means that mechanically fastened tile roof systems installed over battens meet the requirements of the FRSA-TRI Manual and Florida Building Code. To meet these requirements, Table 1A in the FRSA-TRI Manual must be consulted. The batten references in the fastening attachment section provide the required number of fasteners to meet the given uplift requirement.
Also, the FRSA-TRI Manual points out that the installation of battens on slopes above 4:12 is now optional. That being said, installing battens on steeper slopes is a safe practice, as it allows installers to have better footing during installation. Battens can also provide for an easier installation due to the ability to hang multiple tiles on the battens before fastening. Without the battens in a direct deck application, the tile would be installed one at a time.
The committee that decided to make this change in the 5th Edition of the FRSA-TRI Manual did so to address the different types of metal flashings that are used during the installation of a tile roof. Because of the choice between metal with returns or without returns and the possibility of mixing these types on one roof with multiple slopes, the committee wanted to leave the choice to use battens up to the roofing professional.
As an important note: The High Velocity Hurricane Zone (HVHZ) requirements for the use of battens have not changed and caution should be taken when working on projects within the HVHZ area. In these areas, the use of formal NOA’s are required, but in areas outside of Miami-Dade County the roofing professional should be using FBC for tile installations.
The FRSA-TRI Manual states that battens shall be “decay resistant exterior grade. Battens should not be bowed or twisted. Horizontal battens shall be a nominal 1” x 2” x 4’.” Eight foot battens without weep holes at least every four feet or battens made with untreated wood must not be used.
The manual then goes further to state that in a single ply underlayment system, such as one layer of self-adhered underlayment,
“When using battens, back-nailing the underlayment and priming of the deck are optional. Additionally, when using battens, pre-formed metals and transitional flashing are required.”
“Battens must be fastened and secured a maximum of 24 inches on center. The fasteners must be of sufficient length to penetrate a minimum of 3/4-inch into or through the sheathing, whichever is less. If utilizing staples, the battens must be fastened at 12 inches on center. The staples must be a minimum 7/16-inch crown, number 16-gauge corrosion-resistant, and they must penetrate 3/4-inch into or through the sheathing, whichever is less. Importantly, staples cannot be used with adhesive set tile. Battens must be installed leaving a 1/2-inch space between batten ends and between the batten and any metal edge returns. Fasteners shall be compatible with batten material.”
While standard battens do create an air space, maximizing the passive movement of air under the tile is possible using elevated/raised battens or a counter batten system. This has been proven to lower attic temperatures and there are studies that there is an associated R Value to such systems. However, such systems require FBC product approval and interested roofing professionals should contact their roof tile manufacturer for product approval and installation instructions.
The energy benefits from batten and raised batten installations are worth consideration. As the roofing professional, you will need to review the above information and check with the tile manufacturer and the appropriate code to make sure you are installing the battens correctly to meet the codes and the wind uplift requirements.
Manuel “Manny” Oyola, Jr., is the Technical Manager Eastern Region/FL, Eagle Roofing Products. Manny holds a roofing contractors
license and is an active member of the Tile Roofing Institute (TRI). He is also an active member of FRSA’s Codes and Regulatory Compliance and Roof Tile Committees, and on the Codes Subcommittee, as well as participating on the FRSA-TRI Manual Reformatting Committee. Manny teaches roof tile courses for TRI and FRSA.
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