Anchoring to Concrete, Brick or Block — Concrete

Anchoring to Concrete, Brick or Block - Concrete

Anchoring Guidelines for Concrete, Brick or Block

Choosing the concrete anchor best suited to your needs requires consideration of many project specifics, including the characteristics of the base material, such as quality, density and thickness; the type of fixture being fastened, the location of the project and the stresses that will be applied to the anchor.

Considerations:

What are the characteristics of the base material?

Every type of base material has its own limitations and advantages. Determining the properties of your base material will allow you to safely and successfully anchor your fixture.

Brick or Mortar: Like stone, brick and mortar range from hard (brittle) to soft. In hard brick anchors with low-impact and/or low-torque are recommended. In soft brick, a draw-up anchor, such as a sleeve anchor or machine screw anchor, is recommended.

What is the density of the base material?

There are three degrees of density and strength of base materials:

  • Low Density - weak resistance to stress, i.e. drywall and cinder block.
  • Medium Density - moderate resistance to stress, i.e. plaster, tile fiber board and particle board.
  • High Density - significant resistance to stress, i.e. concrete, brick, concrete block and stone.

Resistance to stress will vary based on the density and thickness of the base material. Age and manufacturing standards for material will result in different failure points for each anchor.

What is the thickness of base material?

Measuring the thickness of the base material will help you to determine the length of the anchor needed for your project.

NOTE: For Hollow Core base material it is critical to have the right length anchor so as to be able to secure tightly. For Solid Core base material it is recommended that the thickness of the base material be at least 125% of the anchor embedment depth.

What type of fixture will you be fastening?

Once the characteristics of the base material have been determined, the next step is to address the properties of the fixture.

  1. Weight and Size of the Fixture
  2. Location of the Fixture
  3. Stresses Applied to the Fixture

What is the size and weight of the fixture to be fastened?

Size and weight of the fixture (or what is to be the load on the fixture, as in shelving) are critical in determining not only the type of anchor needed, but the number of anchors needed per application.

Example: If a fixture weighing 100 pounds needs to be anchored and the safe working load of the anchor selected is 50 pounds, then at least 2 anchors will be needed to safely secure the fixture. Additional anchors may be warranted, not because of weight, but because of the size of the fixture. When in doubt, it is best to use more anchors. Be careful, however, that the anchors are not placed to close together. It is typical within the industry to leave at least 10 anchor diameters between anchors.

What is the location of the fixture to be fastened?

Location plays a critical role in determining the type and material of the anchor used.

Considerations include:

  • Will the fixture be indoors, outdoors or subjected to chemical elements?
    • Zinc is acceptable for indoor use where there is no risk of chemicals.
    • Galvanized and Stainless Steel are acceptable for outdoor use.
    • Stainless Steel should be utilized for areas subject to possible contact with chemicals.
  • Will the fixture be fastened to a floor, wall or ceiling?
    • Different stresses are applied to a fixture in different applications. When fastening to a wall, shear strength must be considered in addition to tension strength. When fastening to a ceiling be sure to consider if there will be movement to consider.
  • Will the fixture be close to an unsupported edge?
    • The expansion anchor industry has established a minimum standard of ten (10) anchor diameters for spacing between anchors and five (5) anchor diameters from any unsupported edge. When vibration or sudden impact are part of the load conditions, spacing between anchors should be increased.

What types of stresses will be applied to the fixture?

Concrete fasteners are designed differently, accommodating different types of loads they are meant to secure. The following stresses are type of stresses that may be exerted on the fixture. These stresses are critical factors in selecting the right anchor.

Will your fixture be exposed to:


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