Natural Thin Stone Veneer Surface Preparation

Natural Stone Veneer Installation and Surface Preparation
Preparing the exterior of your home for installation of natural stone veneer starts with preparing the surface over which the stone will be installed. Any installation must begin with a solid, clean wall capable of bearing the load, or weight, of the stone and materials.

Exterior Surface Preparation
A new home installation typically involves installing the stone over wood or metal studs that have been covered with sheathing, moisture barrier, wire mesh, and a scratch coat of mortar. Existing structures with vinyl or wood siding may require the siding be removed down to the sheathing before installation. Sheathing materials include cement board or plywood and provide a durable surface to which all other layers will attach. Moisture barriers can be made of plastic or a composite material, but the most popular is installing one or more barriers of felt paper, similar to what is used under roofing shingles. The requirement and specifications for a moisture barrier are typically defined by local or national building code. Installing wire mesh with a scratch coat of mortar creates the next layer. After drying, another layer of mortar and the stone veneer will be installed.

If these exterior surfaces have been painted, treated, or sealed they may need to be sand-blasted or etched with muriatic acid. Sand blasters are available for rent at many tool rental facilities, requiring the purchase of the sand and personal protective equipment. Sand blasting can take off a lot of material very quickly, so a little practice will be required to remove the right amount of material. Practice on an inconspicuous area to perfect your technique. You should start with a fine grade or grit of sand. It’s graded just like sandpaper, so the higher the number, the finer the sand. Depending upon the surface, you may start with a fine grit in the 100-120 range. Rough surfaces that have been painted will require more effort than smooth surface that have only been sealed. The surface should be free of any glossy sheens when finished. Clean up after sandblasting can take some time, so be sure to allow plenty. Etching the surface with muriatic acid doesn’t require as much finesse, but you will need to take time to prep the area. You need to cover and protect yourself, all vegetation, and any metal items. Muriatic acid will cause serious injury to skin and eyes if it comes in contact with them. Once you have properly prepared yourself and the area, begin by wetting down the surface you intend to etch. Then dilute the muriatic acid to a 10% mixture in a plastic bucket (or as recommended on the packaging – too strong a mixture could damage the surface structurally). DO NOT USE A METAL BUCKET. Scrub small areas of the surface with a nylon or plastic brush. NO METAL BRISTLE BRUSHES. Allow it to sit for about 5 minutes and rinse the area. The surface should be free of any glossy sheens, just like sandblasting. Be sure to rinse and saturate the ground and any vegetation that can into contact with the muriatic acid to dilute the solution further and possibly prevent damage.

Interior Surface Preparation
Most interior installations require, at a minimum, a wire mesh layer with a scratch coat over drywall, plywood, or cement board. Moisture prone areas, such as a shower or bathroom may require a moisture barrier one or two layers thick.