The Crete-Flex screw is manufactured from a 410 stainless steel for added rust resistance in moist atmospheres. It is used for attaching an item to masonry surfaces such as block CMU, brick or concrete.
The Crete-Flex screw is manufactured in a flat head countersunk with a #3 Phillips drive for use where the head must sit below the surface of the item being attached. The flat-headed screw is measured as an overall length including the head. There is also a head style of a slotted hex washer head which requires the use of a 5/16”driver and for use in applications where the head will protrude above the surface of the item being attached. The length of the hex head is measured from underneath the head.
The Crete-Flex masonry screw comes in only one diameter of 1/4”. When reading the description of the screw, the first number refers to the diameter.
Crete-Flex screws come in nine different lengths with the shortest length of 1-1/4” and the longest length of 6”. When reading the description of the screw, the second number refers to the length.
A 7/32” diameter hole must be drilled into the base material using a hammer drill and a carbide tipped masonry bit that meets ANSI standards. Hole size is critical for ensuring proper tolerance and for obtaining minimum holding values of the screw in the masonry material.
The depth of the hole in the base material must be a minimum of 1/4” deeper than the Crete-Flex screw will penetrate (see minimum embedment requirements below). This will ensure that the minimum embedment requirements are met, as well as providing space for dust created during the installation process to fall and remain out of the way.
Each length of Crete-Flex masonry screw is designed to fasten a range of thicknesses of materials. The minimum length screw used for any application is determined by adding the minimum embedment depth of 1” to the thickness of the material being fastened. The maximum length of screw is equal to the maximum embedment of 1-3/4” plus the thickness of the material being fastened.
To install a Crete-Flex through a predrilled hole in the item being attached, it is important that the hole is 5/16” in diameter.
All Crete-Flex screws are packaged 100 pieces per box with one 7/32” carbide tipped bit included.
Use this link to obtain technical information on Crete-Flex stainless steel masonry screws.
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.