The lenght of the tip required on a drilling fastener is determined by adding up the thickness of the top material, any insulation or void between the top material and bottom material, and the thickness of the bottom material. If a hole is larger than the screw thread has been pre-drilled or punched into the top material, only the thickness of the bottom material needs to be considered. The theaded portion of the shank must be long enough to extend into and through the bottom material.

Independent test results available upon request. Lumber for these tests is typical of the woods used in post frame construction. All lumber is constructiongrade with the exception of “economy fir” which is unrated. This lumber was not kiln dried. Tighter grain structure would provide a substantial increase in pullout values. Values with 1” penetration can vary from 240 lbs. to 1150 lbs., depending on wood density. We believe these are typical values found in field applications. These values are ultimate with no safety factors. Recommended minimum penetration is 1”, except for plywood.