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Concrete Anchors & Fasteners is Our Specialty   Questions? Contact Mike   

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1/2" Double Expansion Anchor, 25/Box

   Availability: In Stock
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$48.75 per Box of 25
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Customer Reviews

CONFAST® - 1/2" Double Expansion Anchor

The 1/2" Double Expansion Anchors are preassembled into a single unit and are packaged with 25 pieces per box. Their expansion for the entire length provides the optimal opportunity for successful fastening in masonry material of questionable strength. Whether it is one box or a full pallet, all orders over $25.00 ship with free freight.

  • Bit size 7/8"
  • Minimum embedment 2-1/2"
  • Bolt diameter is anchor size
  • Bolt must be purchased separately
  • Requires a bolt with national coarse threads
  • Rust resistant Zamac
  • Ready to install
  • Threaded cone is inserted first into the hole
  • Do not use in overhead applications
  • Do not expand anchor before installation
  • Free freight on all orders over $25.00
Products specifications
Bit Size 7/8"
Minimum Embedment 2-1/2"
Thread Type 1/2" - 13
2000 PSI Concrete - Pull-Out (lbs.) * 1942
Type Female
Diameter 1/2"
Length 2-1/2"
Material Zamac
Environment Moist
Box Qty 25
Minimum Spacing 8-3/4"
Minimum Edge Distance 4-3/8"
Minimum Fixture Hole Diameter (In Place) 1"
Minimum Fixture Hole Diameter (Hole Spotted) 1/2"
Inside Anchor Diameter-Bolt Diameter 1/2"
Outside Anchor Diameter 7/8"
Length Measurement End to End
Bolt Length Fixture Thickness + Embedment Depth
Brand Name CONFAST®

The 1/2" Double Expansion Anchor is made from Zamac Alloy. This anchor is designed for use in concrete, block, and brick.

The anchor is designed for use in an outdoor, moist environment.

Hole Diameter/Bit Diameter
The 1/2" Double Expansion Anchor requires a 7/8" hole to be drilled in the base material (concrete, block, and brick). The hole should be drilled with carbide tipped bit that meets ANSI standards and used in a hammer drill.

Designated Size
The designated size of the anchor refers to the inside diameter 1/2" of the anchor or the diameter of the threaded rod or bolt that can be inserted into it.

Diameter of Anchor
The diameter of the 1/2" Double Expansion Anchor is 1/2".

Length Anchor
The length of the anchor is 2-1/2", and is measured from underneath the head.

Thread Type
The threads on the 1/2" Double Expansion Anchor are national coarse threads that measures 1/2" with 13 threads per inch, commonly referred to as 1/2"-13.

The anchor is packaged with 25 pieces per box and one (1) correct sized carbide bit.

Minimum Embedment
The 1/2" Double Expansion Anchor minimum embedment into the concrete is 2-1/2". Therefore, the 1/2" Double Expansion Anchor must be installed so that a minimum of 2-1/2" of the anchor is embedded into the concrete.

Fixture Hole Diameter
The hole in the fixture or material being fastened must be larger than the designated diameter of the anchor . The 1/2" diameter anchor requires the hole in the fixture to be 1".

Torque Value
The maximum torque that can be applied to the 1/2" Double Expansion Anchor once installed is 20 ft. lbs.

Spacing between Anchors
Each anchor must be spaced a minimum distance of 8-3/4" from each other when measured center to center.

Edge Distance
It is very important not to install the 1/2" Double Expansion Anchor any closer than 4-3/8" from an unsupported edge of concrete.

Bolt Length
When a bolt is used in conjunction with the anchor , the length of the bolt needed is determined by considering these factors:

  • Flush With Concrete - when the anchor is set flush with the surface of the concrete, add the thickness of the material being fastened to the thread and then add the space for any washers used.
  • Below Surface of Concrete - add the depth below the surface of the concrete to the thickness of the material being fastened, then add the space for the washer, and, finally, add for the thread engagement.

Holding Values - Ultimate Load Values in 2000 PSI Concrete

1/2" Double Expansion Anchor Size

Minimum Embedment

Pull-Out (lbs.)

Shear (lbs.)

1/2" x 2-1/2"




Product Information


Part number

Quantity per Box

1/2" Double Expansion Anchor



Installing a 1/2" Double Expansion Anchor
  1. Drill a 7/8" hole into the concrete using a carbide-tipped bit that meets ANSI Standards B212.15.
  2. The depth of the hole can be deeper or equal to the minimum embedment depth of 2-1/2" which is equal to the length of the anchor .
  3. Clean the hole with a wire brush, vacuum, compressed air, or a blow-out bulb.
  4. Insert the anchor with its threaded end first into the hole.
  5. Place the fixture over the 1/2" Double Expansion Anchor, insert a 1/2" diameter bolt through the fixture and into the 1/2" Double Expansion Anchor.
  6. Use a wrench to turn the anchor clockwise until tight or maximum torque value 20 ft. lbs. is reached.
  7. Always use proper personal protective equipment per manufacturer's and OSHA instructions.

1/2" double expansion anchor - block - building gutter


* The figures above indicate average ultimate tension and shear failure values. A safety factor of 4:1 or 25% of ultimate value is generally accepted as a safe working load. Reference should always be made to applicable codes.

These bits work with the selected anchor
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