Performance of FAST FELT® Tabs vs. Plastic Caps
OVERVIEW OF THE RELATIVE RUPTURE STRENGTHS:
COMPARATIVE "TEAR" TEST RESULTS: Performed by Two (2) Independent Laboratories
The following test results were the "simple average mean" values from designated tear tests performed according to the standards of one of the world's largest voluntary standards development organizations, a trusted source for technical standards for materials and products. All "values" in this section are in foot-pounds ("lbf") units of measurement. In all of the Teat test results described below, the heads of the roofing nails were seated firmly but without crushing the sheet. Results of other tests show that if the roofing nail is either (a) seated loosely or (b) crushes into the felt underlayment, the resulting Tear values are significantly less than when the roofing nails are seated firmly. (For "loosely", the Tear tests were performed with a gap of only 4/100ths of an inch (0.04"), almost immeasurable to the unaided eye.)
Please Note: Plastic Caps are not an approved product in the Florida Building Code, "High Velocity Hurricane Zones". See the Florida Building Code, Section 15 "Roof Assemblies and Rooftop Structures".
At one of the above described laboratories, an additional set of these same Tear tests were performed on the Tin Caps. The resulting "simple average mean" values for the Tin Caps were as follows:
Machine Direction Specimens: 66.3
Cross-Machine Direction Specimens: 60.1
Brief Description of the Tin Cap Tear Failure Observed: In almost all of these Tear tests with the tin caps, the felt underlayment tore at the shank of the roofing nail, with the effect being that the felt underlayment slid under the tin cap. This tear in the felt underlayment, at the nail shank, lengthened until all potential anchoring of the felt underlayment ("tar paper") by the tin cap failed. The felt underlayment is a relatively weak sheet and the tin cap is not adhered to the felt underlayment. (Note the notebook sheet in a 3-ring binder analogy.)
Suggested FAST FELT® Tab Pattern: U. S. (Except Florida) + Canada
FAST FELT® tabs, on ASTM D 226, ASTM D 4869 and/or No 15 and No 30 asphalt saturated felt underlayments, are designed as shown below, and so that, after proper installation, no FAST FELT® tab is further than 18" from another FAST FELT® tab.