Banding, Columns, Door & Window Surrounds Columns & Arches Medallions, Coping, Arches, Columns, & Banding Balustrades, Newel Piers, Sphere Finials, & Planters Pool & Wall Coping Garden Elements Pier Caps Commercial Signage
jQuery Horizontal Image Slider by WOWSlider.com v1.7m

REINFORCEMENTS—COLUMNS

 

Although columns were originally designed as structural support in the Roman and Greek architectural structures, they are used today as decorative sophistication for your grand entrance, whether residential or commercial, your landscaping applications, or inside elegant accent and beauty.

 

Cast stone columns are not structural; they are deliberately decorative architectural design elements. They are designed with the idea that a support structure has been manufactured inside that they encase to complete with the base, column shaft, and capital.

 

Column shafts, bases, and capitals are made in two-piece vertical sections. Each of the pieces have been designed with dowel holes, usually two, to assist with alignment during installation and three-eighths inch joints between the base, shaft, and capital pieces. The column shaft is usually hollowed out to fit the diameter of the support beam that the shaft pieces wrap around.

 

When designing the columns, one must keep in mind that the dynamics of the diameter of the support beam, and the diameter of the column shaft has to present themselves as structurally strong and sound. The column shaft pieces are hollowed out to fit the support beam. There needs to be sufficient width of the cast stone column shaft material to ensure that it is structurally sound and strong enough to maintain the weight of the uppermost pieces of the column, including the capital.

 

Rebar reinforcements must be placed at least one and one-half inch from the face of the column pieces. There needs to be at least four inches width in cast stone material so one inch dowel holes can be formed at the ends of each piece when manufacturing the material or later drilled on-site. The dowel holes must not compromise the strength of the individual pieces by being too close to the outermost or innermost walls of the column shaft pieces. Therefore, the diameter of the inner support beam plus the width of both sides of the column shaft pieces must be mathematically correct to ensure safety and support.

 

Tapered columns are designed, based upon the earliest architectural designs, whereby the lower third shaft portion is a straight column shaft with the tapering of the columns seen in the upper two-thirds of the column shafts. As the column tapers inward, it becomes even more critical to secure enough material in the cast stone column shaft so dowel holes can be successfully inserted when manufactured or drilled on site. The decreasing width of the column cannot compromise its integrity; strength, and support with cast stone pieces too narrow at the top of the column shaft.

 

The two halves of the shaft, base, and capital are connected with the dowels on each side as well as with a stainless steel strap with Tapcon® concrete screws at each joint to ensure the sturdiness of the connection. As we stated, cast stone material is not designed as a load-bearing, structural support item. Yet, there is not much that can hold the column pieces in place, on top of one another, than itself. Therefore, the columns must be constructed to withstand the pressure of the cast stone piece(s) on top of one another.

 

Additionally, there is usually a beam that travels horizontally above the columns that they tie into. Depending on what that beam is constructed of, and how the columns are tied, jointed, or reinforced together, makes a difference on how they withstand movement in the future. Securing the column to a support beam that has been welded into place, does not allow for expansion and movement, thus one will see cracking over time. Skid plates may be an alternative to allow the support beam to rest on the columns while allowing movement in the columns due to expansion and contraction within the structure itself.

 

Weather conditions also play a role in movement, expansion, and contraction. Soft Sealant joints must be checked periodically to ensure there is no void resulting from shrinkage and cracking of the joints.

 

You will usually find three sections per column structure, but it is also based upon individual design and specifications. Interior creations can be created using a vertical half of a column, called a pilaster, to decorate a corner piece of a staircase, room divisions as they butt up against a wall or an entranceway through a foyer. One must consider the overall height of the column half, or pilaster, as it is strongly recommended that the individual pieces not be over eight feet in length or one risks cracking during manufacturing, handling, installing, or movement of the connecting wall.

 

A standard Tuscan capital image portrays how a simple capital and upper shaft piece are assembled. A base and lower shaft combination are provided to demonstrate how the pieces form around the steel column support within the column itself. An overhead view demonstrates how reinforcements are placed to ensure that the column shaft, base, and capital pieces align properly. Dowel holes are strategically placed so each aligns with the next providing reinforcement and conformity as the column is being erected. Additionally, at each juncture, the strapping has been secured to ensure no movement or twisting of the pieces takes place as the next section is placed on top. (Refer to our bulletins on Mortar, Sealants, Cleaning, Allowances for Movement, Basic Design Considerations, Basic Installation Guidelines, and Weather Considerations, and Tips for more ideas.)

 

REINFORCEMENTS — COLUMNS (PDF)

 

The information within this and all our bulletins has been provided as a guideline and based upon statistical data and prior uses. We always suggest that you consult with your engineer, architect or contractor for the best design and use of cast stone for your project. Our design team is always available to answer any of your questions. We do not accept any liability from damages resulting from your interpretation of the data contained within.