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DESIGN TIPS—BASIC INSTALLATION

 

Cast stone is a molded masonry product, architecturally designed for decorative purposes. It is well suited for full veneer wall facings, columns, balustrades, coping trim, banding, fireplaces, window sills and surrounds, door surrounds, decorative medallions, and more. It is excellent for providing color, contrast, decoration, and elegance to both interior and exterior areas for any residential and commercial project.

 

The advantage to using cast stone as opposed to natural stone is that it can be formed to meet your specifications. Designing molds to fit your needs, the material can be vibrant dry-tamped, cured, packaged, and transported to your project location.

 

Additionally, cast stone material is consistent in color and texture. You can control the desired result of cast stone material, whereas you are subject to natural color variations in natural cut stone.

 

Additionally, should you wish creative, intricate, decorative patterns in your stone, cast stone molds are designed for repetitive manufacturing ensuring consistency of material. Natural stone requires the carving of intricate designs by hand where the CNC technology cannot go. Thus, each piece is subject to a variance as it is made individually.

 

Espinoza Cast Stone, Inc., has a team of experienced cast stone designers that can offer you a wide range of project designing tips and cast stone from their state-of-the-art batch plant facility.

 

We have compiled a couple of recommendations for the basic preparation and installation of cast stone material. Please consult with your design team for further recommendations and the additional bulletins found within our web site or the Cast Stone Institute website.

 

PREPARE THE SITE LOCATION

 

As the day approaches the delivery of the cast stone material, the mason or contractor should clean and prepare the project area. Cast stone is porous and should be stored on non-staining materials, above ground, from moisture, and allowed to air. It should be protected from high traffic areas so it is not chipped or cracked by equipment, men and flying debris of passing vehicles.

 

ENVIRONMENT

 

The mason or contractor should ensure that weather and environmental conditions are considered when installing cast stone and masonry material. Grout, chalking and mortar should not be used when temperatures are lower than 46 degrees Fahrenheit, if freezing temperature is expected within 24 hours of installation, or if temperatures are expected to be higher than 90 degrees Fahrenheit.

 

If weather conditions are hot, verify you have made applicable provisions for keeping the installed material moist so it does not dry too quickly. Moist cloths (spray bottles with water) and plastic covers should be considered in extremely hot conditions to prevent quick drying and shrinkage of cast stone materials as well as the mortar, sealants and chalking.

 

DRAWING AND SETTING PLANS

 

The mason or contractor should have a set of drawings and setting plans so they can piece together the multiple sizes and shapes of cast stone material, similar to putting together a puzzle.

 

The mason or contractor should ensure that all material has been shipped and matched to the setting plans. Any chipped, cracked, or damaged material should be reported immediately to the manufacturing plant so replacement material can be manufactured and shipped as quickly as possible.

 

The door surrounds, window surrounds and sills, and the like, should be matched together on a safe surface to ensure that one is working with the correct pieces and profiles for each section of the project.

 

The mason or contractor should make sure that all dowel holes, anchors, lifting inserts and the like that were installed at the time of manufacturing, are correct and accurate. Columns should be designed with dowel holes for alignment. Dowel holes, in the column’s shaft pieces, the capital and the base, ensure that the column halves will be securely aligned properly. The support system of the column (usually a square or circular tube or an “I” beam) should be properly constructed (and supported) so the cast stone column pieces can mount around the support and be secured to it with L clips and brackets, pins, wire, or plates.

 

Proper upper support and bracing must be in place for the breath of expansion between the columns and for the upper portion of the columns before installation. Proper lifting measures must in place to hoist the material as well as support of the cast stone material from the bottom.

 

Banding, coping, and trim pieces should have been manufactured with the appropriate lip for placement on steel lintels or dowel holes. Dowels can be appropriately applied when manufacturing thus the banding, coping or trim pieces will align perfectly throughout, and around the project. Dowels with wires can be installed so the wires can anchor the material securely to the structure while the dowel holes align to the material during installation.

 

Longer pieces for balustrade bases and rails, bandings, coping, and trims may have been manufactured with the concept that field cutting will happen on the job site. Building molds to manufacture pieces in twenty–four to forty–eight inch pieces is a cost savings principle as rapid manufacturing of the same mold can transpire and will turn out more pieces per hour than if the tampers are required to make multiple changes and blocking to the molds as they tamp each piece individually.

 

Once on the job site, it is important to line up the trim, coping, banding, balustrade rails and bases, water tables, veneer pieces and such, before installing with mortar. This will ensure that the mason has the appropriate amount of material before the final install and will prevent over cutting in the field. Right and left returns and corner pieces should be accounted for, and not field cut until all straight pieces has been aligned and ready for install.

 

It is important that the architects and designers consider the size and weight of the cast stone pieces from the start of the planning and designing stages. Prior planning regarding the lifting inserts to assist in lifting the giant pieces into place is a must. This must be coupled with the technology to also provide proper anchoring of the pieces while aligning them perfectly. These large pieces can be attached directly to a steel beam or suspended by metal straps supported by the uppermost support system already in place.

 

When one is installing an archway, where large cast stone pieces will be lifted into place, one must also have both the lifting inserts secured in the stone as well as a means of anchoring the piece to the uppermost part of the archway. Both of these mechanisms must be creatively designed so they are not visible after installation. Proper support from the ground up must be available to insure proper installation, alignment, and protection for the masons installing heavy pieces.

 

A wooden form of the archway or uppermost header section may be required to support the stone that is being fitted, aligned and installed. A plumb line is helpful for ensuring proper placement and alignment of the pieces including any veneer that surrounds any arch, header, window, or doorway.

 

Proper crane or lifting systems must be in place for heavy pieces such as wall caps and pier caps. Some of the pieces can weigh up to one-thousand pounds, and would require too much manpower to lift and install safely. A hoist crane with protective measures along the holding edges is a must for the lifting and placing of heavier stones.

 

TOOLS, PREPARATION AND INSTALLATION

 

The mason should have all the tools required to install the cast stone material. Depending on the type of structure and the pieces being installed the supplies will vary. Cast stone pieces should be separated in order of installation and into the different areas, layers, or elevations that it will be applied. Start at ground up. Mark and drill holes for setting pins, L brackets, anchors, and dowels before starting with each piece of the project. Anchors, masonry ties, L and Z clips, brackets, screws, lintels, and eye bolts for lifting are some of the hardware required to lift and anchor the cast stone material to the structure. Small hand tools, wrenches, screwdrivers, drills, grinders and saws should all be items that are easily accessible.

 

Proper mortar and sealants, as well as all the masonry tools used to apply each, should be considered before beginning with the installation. Deciding which type of mortar or sealant is important. Our bulletin on each should be reviewed. Below is a brief overview of the types of pieces that require the different mortars and sealants and the materials that should be used with them.

 

Be sure to include masking tape, preferably blue painter’s tape, for masking off the stone so it is not stained with any mortar spillage. Protect the profiles that extend out and the corners from damage during the installation and throughout the continued progress of the project.

 

Grey mortar is usually used for installation of cast stone material. Color matched mortar mix should be used for the top one inch of the joint.

 

Mortar joints are usually three-eighths inch for exterior applications; mortar joints are anywhere between an eighth to a quarter inch for interior applications. Verify that you have spacers so you have the same distance between each piece for symmetry.

 

Mortar joints are recommended for masonry-bound trim such as keystones, quoins, date stones, inscription blocks, window surrounds, lintels, and belt courses. It is recommended that one always rake joints back approximately one inch from the cast stone edge and point mortar joints instead of full-bed setting and finishing in one operation. Place a mixture of mortar mix grouting that has been color matched in the top portion. Do not use the grey mortar for pointing. (Refer to our bulletin on recommendations for pointing.)

 

Soft Sealant Joints are recommended for conventional masonry units, head joints at coping stones, joints at column covers, cornices, soffits, window sills, platforms, and all stone sections with projecting profiles, exposed top joints, rigid suspension connections to the supporting structure, and when piece sizes are larger than conventional masonry units (one foot, six inches tall by two feet, six inches long for vertical applications).

Sealant joints are not designed to bear weight, use plastic setting pads, or lead shims when setting the stone on a soft bed joint. It is not intended to adhere to the foam backer rod. Sealant joints will be designed to adhere to parallel surfaces only.

 

There are two most common types of sealants, specified under section 07920; one-part moisture cure and air cure. There are two-part systems available that require mixing of materials to allow for and chemically induce proper curing.

 

Silicone Sealants are excellent sealant materials providing superior weather resistance over a range of temperatures, are easy to apply, are flexible and durable, have a low shrinkage rate and can accommodate movement.

 

Two-part component polyurethane sealants are tough, durable, flexible, and elastic in nature, allowing movement up to fifty percent of the joint width. They form a watertight bond with most building materials.

 

PATCHING

 

If patching is required, confirm that you have wooden or plastic tools for applying the patch material. Your cast stone manufacturer can provide you with patch kits that will assist you in maintaining a color match. Keep in mind that sand colors are in consistent flux because they are mined from the ground. Getting a Patch Kit immediately after manufacturing will ensure that you have the same sand that your cast stone was made from.

 

If you have any stone left over or cracked stone, you do have the option of grinding it up and using the material for patching. Wet the area to be patched thoroughly, place a little bit of white acrylic bonding agent on the chipped piece, making sure you do not get too close to the edges, apply the patching material, leaving just a little extra on top. Once the material has begun to set, use an old clean rag, carpet piece, or a soft brush, to brush the area so it blends with the cast stone and mortar.

 

Cast stone material is decorative and not typically designed for load bearing purposes. After it has cured, it becomes quite strong but proper support systems should be in place to ensure proper anchoring throughout each level of the project.

 

We cannot stress how important it is that careful planning at the start will assist in eliminating disappointment for any homeowner or commercial designer at the completion of the project. There is so little one can do to change the appearance of cast stone after installation; therefore, we strongly suggest that careful consideration and planning are executed from the start.

 

DESIGN TIPS — BASIC INSTALLATION (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.