Cement anchor screws are screws designed to anchor an item to cement. The cement anchor screws can tap threads into a predrilled hole in the cement. Cement anchors screws can be purchased at the local hardware store. Concrete Fastening Systems, Inc. sells the American made Tapcon® brand cement anchor screws online at www.confast.com.
The following information refers to the Tapcon brand cement anchor screw:
Standard Sizes
- Diameter - the cement anchor screw comes in two standard diameters of 3/16” or 1/4”.
- Length – the 3/16” diameter comes in 7 standard lengths of 1-1/4”, 1-3/4”, 2-1/4”, 2-3/4”, 3-1/4”,3-3/4” and 4” the 1/4” comes in 9 lengths of 1-1/4”, 1-3/4”, 2-1/4”, 2-3/4”, 3-1/4”,3-3/4”, 4’, 5” and 6”.
Large Diameter Sizes
- Diameter- the large diameter cement anchor screws come in four diameters: 3/8”, 1/2”, 5/8” and 3/4”.
- Length – each large diameter cement anchor screw comes in different lengths.
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Diameter
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Length
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3/8”
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1-3/4”
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2-1/2”
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3”
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4”
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5”
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1/2”
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2-1/2”
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3”
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4”
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5”
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6”
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5/8”
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3”
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4”
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5”
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6”
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3/4”
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4-1/2”
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5-1/2”
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6-1/4”
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Coatings
The standard diameter cement anchor screw is coated with a blue Climaseal® coating to help rust resistance. The large diameter cement anchor screws are coated with a silver Climaseal® coating.
Head Types
The 3/16” and 1/4” come in both a hex washer head and a flat phillip countersunk head while the large diameter dement anchor screws come only in a hex washer head.
Hole Diameter
The diameter of the hole that needs to be drilled into the base material is slightly smaller than the designated diameter of the cement anchor screw being installed. The hole must be drilled with a carbide tipped bit that meets ANSI standards and is used in a hammer drill. The hammer drill must be set in the hammer and rotation mode. The hole tolerance is critical for the cement anchor screw to obtain minimum holding values in the cement.
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Diameter of Cement Screw Anchor
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Diameter of Hole in Base Material
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3/16”
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5/32”
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1/4”
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3/16”
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3/8”
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5/16”
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1/2”
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7/16”
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5/8”
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1/2”
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3/4”
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5/8”
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Hole in Fixture
The hole in the fixture must be larger than the designated diameter of the cement screw anchor being installed to insure clearance before the tapping threads in the cement.
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Diameter of Cement Screw Anchor
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Hole Size Fixture
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3/16”
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1/4”
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1/4”
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3/8”
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3/8”
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1/2”
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1/2”
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5/8”
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5/8”
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3/4”
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3/4”
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7/8”
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Depth of Hole
The hole must be drilled to a depth that is 1/4” deeper than the screw will penetrate the base material and is deep enough to meet minimum embedment requirements. This extra space at the bottom of the hole is important because it allows space for the dust created during the tapping process to fall into and out of the way to insure proper installation.
Minimum Embedment
The cement anchor screw must be embedded into the concrete a minimum of 1” in order to reach minimum holding values.
Maximum Embedment
Cement anchor screws must not be embedded into the base material further than 1-3/4”. Deeper embedments will create installation problems as well as fastener failure. Installation in hard abrasive base material may create installation problem at embedments less then maximum embedments.
Determining Length of Screw
The minimum length of cement anchor screw to use for any particular application is determined by adding the thickness of the material being fastened to the minimum embedment depth of 1”. The maximum screw that should be considered is determined by adding the thickness of the material being fastened plus the maximum embedment of 1-3/4”.
How to Install
- Drill proper size hole in cement using an ANSI standard carbide drill bit in a hammer drill set in the hammer and rotation mode.
- Clean the hole in the cement using a wire brush, compressed air or vacuum.
- Insert cement anchor screw through the hole in the fixture and into the hole in the cement.
- With the proper sized driver for the type of head on the cement anchor screw being installed, turn the screw clockwise until the head of the screw is tight against the material being fastened.
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: Michael Pistorino, Concrete Fastener Specialist