Stone Installation – A more detailed guide at the bottom of the ‘About Us’ Page
I. Surface Preparation
A. Wood, Wallboard, Paneling, Plywood
On an exterior surface, two layers of weather resistant barrier of 15 lb felt or better must be applied before installing metal lath. The barrier should be applied horizontally with the top layer overlapping the lower layer not less than 4 inches. If vertical joints occur, the barrier should be lapped a minimum of 6 inches. Cover entire surface area with a 2.5 lb. diamond wire mesh. Exterior applications require a galvanized metal lath. Metal lath should be attached using galvanized nails or staples overlapping sides by not less than 1/2” on sides and no less than 1” on ends. Nails or staples should be 6” on center vertically and 16” on center horizontally into studs a minimum of 1”. Metal lath should be kept flat against the surface and the pockets of the mesh pointing upwards.
No surface preparation is necessary if the masonry surface (brick, block, concrete) is clean. Painted, sealed or treated surfaces that are permanently bonded can be coated with a bonding agent or covered with metal lath using corrosion resistant concrete nails.
Surface preparation is the same as for wood related preparation except use self-tapping screws on the metal lath that penetrates a minimum of 3/8” beyond the inside surface.
II. Scratch Coat
Use Type S mortar mix for installation. Follow mixing instructions on bag to blend to a creamy paste. For small projects, a polymer tile mortar may be used. Apply a thin coat of mortar to completely cover the metal lath or masonry surface. Scratch the surface with a rake or masonry tool to prevent having a smooth surface. A helpful tip: mark level lines 6” to 12” apart in mortar, using a level and trowel, a string, or a chalk line to ensure the stone will be straight and level. The coating will provide a firm bonding surface for the stone veneer. Some local codes require the scratch coat dry for 48 hours before applying the stone. Check the local building codes prior to installation.
Depending on the job and type of stone, installation may begin at the top or bottom of the wall. Starting at the top will aid in keeping the stone clean. Lay out stones randomly near work area. If applicable, corners should be installed first alternating short and long legs. The back of the stone should be brushed to remove dust prior to applying mortar. Apply a 1/2” thick layer of mortar to the back of the stone and press the stone firmly against the substrate using a wiggling action to insure a good bond. The mortar should squeeze out around the edges of the stone. Remove any excess mortar with a trowel and fill any voids on the stone’s exposed edges. Stagger the joint lines both horizontally and vertically for a finished appearance. If needed, stones may be cut or shaped with a diamond or carbide blade, mason’s trowel, hatchet or nippers. If mortar should get on the stone face, wait until it dries and clean with a stiff brush. NEVER USE A WIRE BRUSH OR ACID TO CLEAN STONE. Do not use a sponge to wipe or remove the mortar as it may stain the surface of the stone.
If a grout line is employed in the laying of the stone, typically one half (1/2) inch spacing between the stones, a grout bag is used to fill in the joints. Fill the grout bag with the mortar mixture, creamy paste desired, and squeeze the small end into the joint area to be filled. Try to avoid getting grout on the face of the stone. If this occurs, allow to dry and brush off with a stiff brush.
IV. Finish Joints
Allow the mortar to start becoming firm and using a striking tool, scrape away all excess grout in the joint and also to force the mortar into any voids. After working the joints use a hand broom to clean loose mortar from the joints and the stone face. NEVER USE A WIRE BRUSH OR ACID TO CLEAN STONE.
V. Clean Stone
Use a non-etching concrete cleaner to remove clay, dirt, mortar residue, or other stains on stone. A pressure washer may be used to clean stone as long as it does not exceed 3000 psi, a yellow tip (wide fan) is used, and a minimum distance of 18” is kept back from the stone.
Thin Brick Veneer
Follow same surface preparation and installation steps as stone. To establish a 50/50 bond some bricks may have to be cut.