Masonry screw anchors are screws that tap threads in a pre-drilled hole in masonry. The common name for these screws is Tapcon®. Masonry screws manufactured by ITW Redhead are made in America and sold by Concrete Fastening Systems, Inc.
Masonry refers to the material used in the construction of buildings made up of individual units bound together with mortar. Masonry usually refers to brick or block, but can also include stone, marble, and granite.
Screw anchors are screws made from steel. They are plated with hardened threads that allow the threads to tap hard, abrasive material such as masonry. The screw anchors’ threads are specially designed not only to tap the masonry but also to remove the dust created during the tapping operation. The thread design of the Tapcon® brand screw alternates high and low with notches cut into them to allow removal of dust.
Tapcon® brand masonry screw anchors are the original masonry screw anchor developed and manufactured in the United States since 1978. Many of the masonry screws sold are manufactured overseas and do not meet the same standards as the Tapcon® brand masonry screw anchor. As an indication of the importance of the blue Tapcon® masonry screw, off brand masonry screws are manufactured to resemble them by copying their blue color. The original and current Tapcon® masonry screw anchors are blue with a special rust-resistant coating called Climaseal®.
The standard Tapcon® brand masonry screw anchor is available in two diameters of a 3/16” and a 1/4”. Large Diameter Tapcon masonry screw anchors are sold in 3/8”, 1/2”, 5/8, and 3/4” diameters. Stainless Steel Tapcon® brand masonry screws are also available in a 3/16” and 1/4 ” diameter as well as the large diameter stainless steel in 3/8” and 1/2”diameters.
The diameter of the hole that needs to be drilled into the masonry is smaller than the designated diameter of the masonry screw anchor being installed. The 3/16” diameter requires a 5/32” hole, the 1/4” diameter requires a 3/16” hole and the large diameter tapcon with a 3/8” diameter requires a 5/16” hole, the 1/2” diameter requires a 7/16” hole, the 5/8” diameter requires a 1/2” hole and the 3/4” diameter requires a 5/8” hole.
When drilling a hole in the masonry to install masonry screw anchors, the hole must be drilled a minimum of 1/4” deeper than the masonry screw will penetrate the masonry. The extra depth will allow space for any dust that is created during the tapping operation to fall, which could negatively affect the installation process.
Adding the thickness of the material being fastened plus the minimum embedment of 1” will determine the minimum length of the masonry screw anchor used. The maximum length of masonry screw anchor to be used is calculated by adding the maximum embedment of 1-3/4” plus the thickness of the fixture being fastened.
The masonry screw anchor can be installed in the masonry unit itself or the mortar joint between the masonry units. The holding value of a masonry screw anchor is dependent on the quality of the masonry unit as well as on the quality and quantity of mortar in the mortar joint.
Step 1: Using the correct diameter drill bit for the masonry screw being installed, drill a hole with a hammer drill a minimum of 1/4” deeper than the depth the masonry screw will penetrate the masonry.
Step 2: Position hole in the fixture over a hole drilled in masonry and insert masonry screw through the fixture and into the hole in the masonry.
Step 3: Turn the masonry screw clockwise until the masonry screw is flush and tight against the surface of the fixture being fastened.
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.