Mike Fulton, National Manager of Technical Training and Compliance, O’Hagin
Fasteners for roofing applications vary greatly depending on the type of roof covering being applied. In the below segment we will look at several different applications where these fasteners have different requirements for both uplift and corrosion resistance.
The Roofing Fastener Requirements for the 2017 Florida Building Code are referenced below, including HVHZ sections, depending on which counties and municipalities the roof is being applied. Chapter 15 contains these requirements, which also references Roof Tile
Applications as set forth in the FRSA/TRI Florida High Wind Concrete and Clay Roof Tile Installation Manual, Fifth Edition.
1506.5 Nails.
Nails shall be corrosion-resistant nails conforming to ASTM F1667 or an equal corrosion resistance by coating, electro galvanization, mechanical galvanization, hot-dipped galvanization, stainless steel, nonferrous metal and alloys or other suitable corrosion-resistant
material, or corrosion resistance shall be demonstrated in accordance with TAS114, Appendix E (HVHZ).
1506.6 Screws.
Wood screws conform to ANSI/ASME B18.6.1. Screws shall be corrosion resistant by coating, galvanization, stainless steel, nonferrous metal or other suitable corrosion-resistant material. The corrosion resistance shall be demonstrated through one of the following methods:
1. Corrosion resistance equivalent to ASTM A641, Class 1;
2. Corrosion resistance in accordance with TAS114, Appendix E; or
3. Corrosion-resistant coating exhibiting not more than 5 percent red rust after 1,000 hours exposure in accordance with ASTM B117.
1507.2.6 Fasteners.
Fasteners for asphalt shingles shall be galvanized, stainless steel, aluminum or copper roofing nails, minimum 12-gage [0.105" (2.67 mm)] shank with a minimum 3/8" diameter (9.5 mm) head, of a length to penetrate through the roofing materials and a minimum of 3/4" (19.1 mm) into the roof sheathing. Where the roof sheathing is less than 3/4" (19.1 mm) thick, the nails shall penetrate through the sheathing. Fasteners shall comply with ASTM F1667.
1507.3.8 Application.
Tile shall be applied according to the manufacturer’s installation instructions or recommendations of the FRSA/TRI Florida High Wind Concrete and Clay Roof Tile Installation Manual, Fifth Edition where the basic wind speed, Vasd, is determined in accordance with Section 1609.3.1 or the recommendation of RAS 118, 119 or 120.
Fasteners for roof tile applications are held to a slightly higher standard than most roofing fasteners.
Underlayment Fasteners – nails or cap nails shall be of sufficient length to properly penetrate 1" into or through the thickness of the deck, whichever is less. Minimum 12 gauge.
Tin tags – Shall be not less than 1-5/8” or greater than 2" in diameter and a minimum 32 gauge steel sheet metal.
Rake Fasteners – For trim tile, fastener shall be of sufficient length to penetrate a minimum of 3/4” into the substrate or rafter. Nails shall be a minimum 10d nail, 11 gauge. Screw shall be a minimum #8 screw.
When using horizontal battens, fasteners must be compatible with the batten treatment. Battens treated with ACQ chemical for example, are highly corrosive and typically need special treatment. Some nail manufacturers will allow certain galvanized fasteners to be used with pressure-treated/ACQ battens, but most have disclaimers that only recommend stainless steel.
Fasteners for roof tile attachment must conform to ASTM 641 Class 1 corrosion resistant standards. Note: (as stated in the FRSA/TRI Florida High Wind Concrete and Clay Tile Installation Manual 5th Edition) “ASTM 641 Class 1 is a nail specification that can be converted to screw fasteners through performance-based testing (ASTM B 117). Each manufacturer is responsible for supplying this support data. Minimum #8 course thread.” Not all have been tested to this standard, but use the Miami-Dade county specification TAS 114 Appendix E testing standard. This TAS 114 Appendix E has been accepted by most municipalities as an equal to the B117 testing. This test uses a pristine, non-driven fasteners, but again, is acceptable. It’s noteworthy that the uplift resistance values of ring shank nails in 19/32 plywood requires an 18 to 22 ring per inch pattern. FRSA/TRI Florida High Wind Concrete and Clay Tile
Installation Manual 5th Edition Table 3. Also notable is TAS 114 Appendix E (Less Than 1,000 hours [Typical 280 hours] in the ASTM G85 salt spray), where the TAS 114 Appendix E requires 1,000 hours in the ASTM G85 Salt Spray. These products are listed on the Miami-Dade site, http://www.miamidade.gov/building/control-forms.asp
1507.4.4 Attachment.
Metal roof panels shall be secured to the supports in accordance with the approved manufacturer’s fasteners. In the absence of manufacturer recommendations, the following fasteners shall be used:
1. Galvanized fasteners shall be used for steel roofs.
2. Copper, brass, bronze, copper alloy or 300 series stainless-steel fasteners shall be used for copper roofs.
3. Stainless-steel fasteners are acceptable for all types of metal roofs.
4. Aluminum fasteners are acceptable for aluminum roofs attached to aluminum supports.
1507.9.7.1 Nails.
Fasteners to attach wood shakes shall be Type 304 (Type 316 for coastal areas) stainless steel ring-shank nails with a minimum penetration of 3/4" (19.1 mm) into the sheathing. Each shake shall be attached with a minimum of two fasteners.
1517.5 Fasteners.
1517.5.1
Nails shall be minimum 12 gauge, annular ring shank nails having not less than 20 rings per inch, heads not less than 3/8" (9.5 mm) in diameter; and lengths sufficient to penetrate through the thickness of plywood panel or wood plank decking not less than 3/16" (4.8 mm), or to penetrate into a 1" (25 mm) or greater thickness of lumber not less than 1". Nails or wood screws shall be hot-dipped electro-or mechanically galvanized to a thickness sufficient to resist corrosion in compliance with TAS 114, Appendix E,
Section 2 (ASTM G85). All nails shall be listed by a certification agency. All nail cartons or carton labels shall be labeled to note compliance with the corrosion-resistance requirements. No roofing material shall be fully or partially adhered directly to a nailable deck, unless otherwise noted in the roof assembly product approval.
1517.5.2
Such fasteners shall be applied through “Tin caps” no less than 1-5/8" (41 mm) and not more than 2" (51 mm) in diameter and of not less than 32 gage (0.010") sheet metal. “Cap nails” or prefabricated fasteners with integral heads complying with this section shall be an acceptable substitute. All “tin caps,” “cap nails” or prefabricated fasteners with integral heads shall be tested for corrosion resistance in compliance with TAS 114 Appendix E, Section 2 (ASTM G85), and shall be product control listed. All of cartons or carton labels “tin caps,” “cap nails” or prefabricated fasteners with integral heads shall be labeled to note compliance with the corrosion-resistance requirements.
A list of approved fasteners (HVHZ) is available at http://www.miamidade.gov/building/control-forms.asp.
In conclusion, there are a few things to remember. One, be sure the fastener you choose meets both corrosion resistance and uplift resistance requirements for the application. Two, metal roofing manufacturers and manufacturers of low slope roofing have specified
fasteners that comply with their warranties and product approvals. And three, when in doubt, always verify with the local code jurisdiction. Happy Roofing!
Mike has worked with O’Hagin for 20 years and has been the National Manager of Technical Training and Compliance for the past 12 years. He is a member of FRSA’s Roof Tile and Codes and Regulatory Compliance Committees, as well as the TRI Southeast Technical Committee.
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