Start by making sure you have the right amount (square footage) of stone veneer to complete your entire project, and you have the correct layout of your stone design. When laying out your design, mix together the stones from multiple boxes and lots to ensure all the colors and stone sizes are randomly but evenly dispersed across the entire project. Failure to do this may result in large sections with areas that appear not to match the rest of the project. This is actually a common error for an inexperienced installer.
Mason’s Mark Stone Veneer can be applied directly to any unpainted or unsealed masonry surface, and can even be applied over a wood or drywall surface with a little surface preparation. Be sure to download a copy of the Masonry Veneer Manufacturers Association Installation Guide (4th Edition) for a detailed explanation of the recommended building code requirements you will need to follow in order to ensure a long lasting and weather proof installation.
If the stone veneer is to be installed to an exterior non-masonry surface, two layers of a water resistant vapor barrier (WRB or House Wrap) must be laid in accordance with generally accepted building practices before installing your stone veneer. A metal lath is installed over the House wrap using 1″ roofing nails approximately every 6″, being sure to secure the metal lathe to wall studs as often as possible.
Prepare a masonry scratch coat by covering the entire metal lath surface with the mortar mixture. Failure to complete this simple step can result in adhesive failure of the stones. The mixture should be squeezed into the lath and be about ½ inch thick. It is recommended that a Type-S Cement or Type-N mortar with a bonding agent be used. Once the surface of your scratch coat is firm and dry enough to leave a thumbprint, scrape horizontal grooves into the coat, using a metal stucco or masonry scarifier. The scratch coat should be allowed to dry and harden, at least 24 hours, before applying the stone veneer.
Prepare the stone veneer mortar mix. The mix should be a mix of about 2 parts sand and 1 part Portland Type-S mortar. Mix thoroughly until a paste consistency similar to a smooth peanut butter is obtained. Make sure there is enough water in the mix to achieve a smooth and workable consistency.
Apply a ½ inch thick mortar layer to the back of the stone and place the stone on the wall using a slow back and forth rotating motion and some firm pressure for about 5-7 seconds. This will cause some of the mortar to ooze out from behind the stone and a weak bond will be created. Be sure to immediately check your level and make any adjustments the stone because in just few minutes the stone can no longer be moved without breaking its bond to the wall. Many styles of ledge or stack stone require a tight fitting installation but other styles like limestone or fieldstone look best with a mortar joint. Be sure to leave a consistent and appropriate space between your stones as you move along the wall.
It is recommended that your stone veneer be installed first on all corners alternating the short and long sides back and forth from bottom to top. Once the corners are completed you may continue with the flat stone by installing them into the corners and working simultaneously up and across the wall as if building a pyramid. Be sure to minimize the use of and hide any trimmed edges as much as possible by placing them in areas where they will not receive focal attention. Always start at the bottom and work your way up and across. Be extra careful not to drop any wet mortar onto installed stones as this may create a stain that will be hard to remove.
It is very important NOT to attempt to remove any wet mortar accidentally dropped onto your stone immediately. Wait until the mortar is dry but soft and gently brush it away. Attempting to clean off wet mortar with any liquid will result in the mortar spreading and badly staining the surface of your stone veneer. Be patient and allow it to dry out a little bit before you brush it away with a dry brush or cloth.
If your new stone veneer wall requires a mortar joint, it should be allowed to dry for 24 hours before the mortar joint is applied. Begin by overfilling all of the mortar joints using a masonry mortar bag. It is critical that the mortar used be very smooth and have no clumps or rocks in the mix. Once the mortar is dry but still soft use a masonry pointing tool to push the mortar into the joint and smooth it out. You can then use a straw masonry brush to smooth out the joints even more by gently sweeping them clean.