III.  Preparing the Surface for Installation

            1.  Rigid Backwall Installation:  Cover the entire surface area where OCS veneer will be applied with a weather resistant barrier and install all necessary flashing. 

            2.  Clean and Untreated Concrete, Masonry, and Stucco:  Check poured concrete closely, to see if the finished surface contains any release agents such as form oil.  If it does, acid etch the area and rinse thoroughly as this will prepare the surface for an adequate bond.  No further preparation needed.

            3.  Dirty, Painted, or Sealed Concrete,  Masonry and Stucco:  For the stone to bond, the surface area needs to be free of any foreign substance such as paint, dirt, or sealers.  If these substances are present, sandblast or water blast until the area is clean and free of these foreign substances.  If the area cannot be cleaned completely, metal lath can be nailed to the concrete, masonry, or stucco using galvanized concrete nails.

            4.  Metal Buildings:  Apply paper backed metal lath using adequate galvanized screws over a primary weather resistant barrier.

IV. Installation Procedures

            1.  Lay Out the Stones:  It is recommended that prior to installation a quantity of stone should be laid out giving you a good idea of the shapes, sizes, depths and color pattern.  This allows you to visualize the desired pattern and give you a selection of stone to choose from.  Thick stones should be place beside thin stone,   wide beside narrow, smooth beside textured.  Mix stones from several boxes to ensure a good blend of sizes and color.

            2.  Mixing Mortar:  Mortar can be mixed in a mechanical mixer or by hand.  Mortar for OCS stone veneer is mixed very similar to brick or block mortar, the only difference is the amount of sand.   Mortar for stone has less sand which gives the mix more Portland cement per unit.  This gives more bonding power to the  mortar.  The mortar should be mixed 2 parts sand to 1 part type S mortar mix, water should be added to obtain the proper slump.

            3. Appling Metal Lath:  The weather resistant barrier, flashing and metal lath should be applied according to the directions outlined in section II.

            4.  Appling the Scratch Coat:  A ½ inch coat of mortar should be applied to the   metal lath using a mason’s or plaster trowel and allowed to dry.   Scratch the surface area to allow for a good bond when setting the stone.

            5.  Setting the Stones:   OCS stone veneer can be installed from the top down, but the most common method is from the bottom up.  A masons level should be used periodically to ensure the stones are installed level and plumb.  Level chalk line can be applied to the scratch coat to assist in proper installation.  Completely cover the back surface of the stone with  ¾ inch of mortar and firmly press onto the prepared wall allowing mortar to squeeze out around the stones edges.  Use trowel to strike off excess mortar before installing the next piece.  All corners have a long and short side, these should be alternated in opposite directions as you apply them.  To simplify installation, stone around windows, doors and corner stones should be installed first.

            6.  Consistent Joints:  Whether you are doing a dry stack or a mortar joint application, all joints should be consistent.  Cutting and trimming the stones may be necessary to achieve the consistent and desired joint.

            7.  Cutting and Trimming Stones:   Stones can be cut to obtain the desired fit, by using a hatchet, nippers or an electric saw with a diamond blade.  Cutting should be done outside using safety glasses and a dust mask.  Cut edge should be hidden from sight.  To conceal the raw edges cover with mortar when installing.    Cut edges should be position up when above eye level and down when below eye level.

V. Joints and Grouting

Grouting may be necessary or desired after stone is set in place.  Grouting technique can give the stone many different appearances.  If mortar smears when grouting , allow to dry and brush with a soft bristled brush.  Never use a wet or a wire brush to remove a mortar smear.

            1.  Drystack:  Drystacked stone installation is achieved by stacking the stone with little or no joint at all.  When setting the stone mortar will seep between the stone, once the mortar is set, striking the joint with a sharp object will give the appearance of no joint at all.

            2. Standard Joint:  This is achieved by laying each stone approximately ½ to ¾ inch apart.  Once stone is laid, fill grout bag ½ full of mortar and squeeze mortar into joint area filling any voids.  When the mortar becomes firm or thumb print   dry, it should be pointed up with a wooden stick or a metal jointing tool.  Rake out  mortar to the depth desired.  Even joints will give a professional looking finish.

            3.  Over Jointing:  This technique is becoming more popular, giving the stone an old world rustic appearance.   The stone is set similar to the standard joint, however grouting should overlap the stone, widening the joints and making them irregular.  This technique is used in the OCS cobble and field stone profiles.