The standard blue screw comes in two diameters of 3/16” and 1/4” while large diameter Tapcons comes in of 3/8”, 1/2”, 5/8” and 3/4”. The diameter of the blue screw to use for any application is determined by the holding values required, by the diameter of the hole in the fixture or if an engineer has specified it. The blue screw - Tapcons or duplicates - are designed for use in solid concrete, brick or block (CMU) base materials.
The blue screws come in different lengths ranging from 1-1/4” to 6”. The length of the blue screw to use for any application depends on the thickness of the material being fastened and the embedment depth. To determine the minimum length of blue screws to use, add the thickness of the material to the minimum embedment depth of 1”. To calculate the longest blue screw’s length, add the thickness of the material being fastened to the maximum embedment of 1-3/4”. The hex head blue screw’s length is measured from underneath the head, while the flat-headed blue screw is measured as an overall length including the head.
Each diameter of blue screw requires a specific diameter hole be drilled into the base material. Holes size is critical for the blue screw to have holding values and must be drilled using a hammer drill with a carbide-tipped drill bit that meets ANSI standards.
|Diameter Tapcon||Diameter of Bit|
The hole must be drilled to a depth of 1/4” deeper than the blue screw will penetrate the base material. This leaves space for any dust to fall into that is created during the installation process. As the blue screw is inserted into the hole, the lead threads tap threads into the base material. This tapping process creates dust and must have a place to go or it will interfere with the proper installation.
The size of the head determines the size of the socket that must be used to install the blue screw. Both diameters of blue screw have a different head size and socket size. The flat head Phillips tapcon requires a #2-bit tip for the 3/16” diameter and a #3-bit tip for the 1/4”. The 3/16” diameter blue screw needs a 1/4” nut driver or socket, and the 1/4” blue screw uses a 5/16” nut driver or socket
As with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications. This article is meant to serve only as a basic explanation of concrete fasteners. Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.