Stone veneer is a building material designed to replicate natural stone. It is comprised of a lightweight concrete, and is cast in a mold that mimics the features of natural stone. Stone veneer is typically installed on top of wood surfaces with metal laths (a mesh foundation similar to a window screen) filled with mortar beneath. This ensures there will be a tight bond when you cement individual veneer sections in place. With this finish comes occassional repairs. You can easily do these yourself with a little preparation and know-how.
The amount of preparation required for stone veneer repair varies with the type damage. If a veneer section has broken loose--and the underlying metal lath has been ripped or pulled out--you're looking at complete replacement. According to ThisOldHouse.com, one tip for ensuring that the lath is installed correctly is by running a gloved hand along its surfaces. The surface that should face outward on a wall will be rough to the touch, and produce a cheese grater-like effect. The same source recommends chipping away old mortar with a hammer and chisel, and then scrubbing it with a sturdy wire brush. Once a space has been cleared, a new section of lath can be nailed into the underlying wall. The lath then needs to be covered with mortar and spread with a trowel. It's best to spread a layer of mortar a half-inch thick. Once dry, this mortar can be scored, or given ridges, by running over it with a notched trowel. It will then be ready for a new stone veneer section. If only the stone veneer section is damaged (and not the underlying lath), it's still beneficial to chisel and brush out a little bit of underlying mortar, according to HomeTips.com. This will create space for the adhesive mortar that's used on the back of new veneer sections being installed.
Once the installation area is prepped, a new stone veneer section can be fitted, shaped, and put in place. According to ThisOldHouse.com, it's always beneficial to dry fit (put in place without an adhesive) the veneer sections first, to ensure they fit securely. According to the same source, the mortar used on the back of the replacement stone veneer should be applied with a pointed trowel. The trowel can also be used to make V-shaped pockets in the mortar, which will help the veneer section bond when it's put in place. HomeTips.com recommends individuals use a Type N, weather-resistant mortar that is sold dry and mixed at home. It's available at most hardware and home improvement stores. According to the same source, once stone veneer replacement pieces are secured, a jointer (or other small pointed tool) can be run over the seams. This will give the joints surrounding the replacement section a concave appearance.