How They Work
Tapcon masonry screws work by tapping threads into the side wall of a predrilled hole in masonry as they are screwed into the material. The hole in the masonry must first be drilled using a matched tolerance carbide tipped masonry bit, used in a hammer drill that is set in the hammer and rotation mode. Once the proper size hole is drilled the Tapcon screw is installed using a straight rotation drill. As the Tapcon is driven into the hole the lead thread taps threads, by cutting away and then removing the material until the screw is embedded to the proper embedment depth.
Diameters of Tapcon Screws
The Tapcon brand masonry screw comes in two diameters of 3/16” and 1/4”. Large diameter tapcon are available in diameters ranging from 3/8” to 3/4”.
Matched Tolerance Hole
To insure minimum holding values, the hole in the masonry must be drilled using a bit that matches the hole tolerance required for the Tapcon screw. Using an ANSI standard carbide tipped bit will insure proper hole tolerance. The bit diameter required for all tapcon screws is slightly smaller than the designated diameter of the screw being installed. For example, a 3/16’ requires a 5/32” hole. Using a bit that does not match the tolerance required may decrease the holding values, may provide no holding values or will not allow the tapcon to be installed.
Critical Hole Depth
The depth of the hole required is critical to insure that the Tapcon screw is installed to the proper embedment depth. The hole must be drilled a minimum of 1/2” deeper than the screw will penetrate the masonry. This extra room allows space for debris created during the installation process to fall into and out of the way. This extra hole depth also insures that the screw will not bottom out in the hole before it reaches the embedment depth required. If the hole is drilled too shallow then the screw will bottom out and continued torque will shear the tapcon off in the hole.
Tapcon masonry fasteners can work well in most masonry materials, such as mortar, brick, block or concrete. If used properly, a Tapcon screw works very well and is a reliable method for attaching an item to masonry material. Occasionally, the Tapcon may not be the best fastener for the job depending on several conditions. If the base material is abrasive and/or very hard, then the lead thread that taps the threads in the concrete may wear down before the screw reaches minimum embedment of 1”. Sometimes the screw may become stuck in the hole and can no longer be inserted any deeper or be removed, and continued torqueing may shear the screw shank. In these cases, an expansion type masonry fastener must be used to allow the fastener to expand against the masonry.
Reusing Tapcon Screws
The Tapcon masonry screw can be reused as long as the lead thread is intact and able to tap threads. Tapcons should never be reused in the same hole because the holing values will be reduced. A Tapcon can be taken out of one hole and then be reinstalled in another, but should never be installed in the same hole. A new screw should never be installed in a hole from which another Tapcon screw was removed. A Tapcon should not be reused in the same hole because the base material in the hole where the threads were tapped may crumble during removal and/or reinsertion.
Two head styles are available: the hex washer and the flat countersunk phillips. The hex headed Tapcon is used when the head of the fasteners sits on top of the surface of the item being fastened. The flat countersunk headed screw is used when the head is countersunk in the material being attached if the top of the screw sits flush with the surface.
The size of the driver is dependent on the diameter and head type of Tapcon being installed. A 3/16” Tapcon uses a 1/4” hex and a #2 phillips driver; the 1/4” requires a 5/16” and a #3 phillips driver.
Required Length of Screw
To determine the minimum length of screw needed for any application, add minimum embedment depth of 1” to the thickness of the material being fastened. Maximum length of screw is calculated by adding the maximum embedment depth of 1-3/4” to the thickness of material being fastened. The hex headed screw is measured from underneath the head
Installing the Tapcon Screw into Masonry Materials
- Using a hammer drill and a carbide tipped masonry bit meeting ANSI standards, drill a hole with the required diameter of Tapcon masonry screw being installed. Make sure that the depth of the hole will be a minimum of 1/2” deeper than the tapcon concrete screw will penetrate.
- The hole must be cleaned of all dust and debris by using a wire brush, compressed air or vacuum. Move the item being fastened and align the hole over the hole in the base material.
- Insert your Tapcon concrete screw through the hole in the fixture and into the hole in the base material.
- Using a wrench or drill, rotate the screw until the head of the Tapcon concrete screw is tight against the surface of the fixture. Make sure that the Tapcon is not over-torqued because this may strip the threads in the base material and cause the Tapcon concrete screw to spin in the hole.
Blue Hex Head Tapcon Concrete Screw
Blue Flat Head Tapcon Concrete Screw
Hex Head Stainless Steel Tapcon Screw
Flat Head Stainless Steel Tapcon Screw
Large Diameter Tapcon Zinc Plated - LDT
Large Diameter Tapcon Stainless - LDTS
Please remember with all fastening jobs to keep safety in mind. Always follow safety instructions on all tools, and refer to manufacturer's installation instructions when available and always remember to wear safety goggles!
Article written by: Bob Carlisle, President Concrete Fastening Systems, Inc