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NATURAL THIN STONE VENEER INSTALLATION GUIDE

 

PREPARATION

 

General Surface Preparation:

If there is a chemical film on the wall it needs to be removed. In many instances, the film may be removed with sandblasting or etching with masonry detergents. The use of acid to remove the film is also a consideration however, in all cases you should check with the manufacturer of the product(s) to make sure it will not damage the underlying surface. The removal process will also make the wall surface less smooth which will aid in the installation process.

 

Concrete Block or Brick:

Natural Thin Stone Veneer can be applied directly to any new or existing concrete block or brick surface. It is important to make sure that the existing surface and wall is sound and without defects, and that the surface has not been painted or sealed. In the case of a poured concrete wall, all form release chemicals should be either sandblasted or removed with a masonry detergent before the application of the natural thin stone veneer.

 

Framed Exterior Walls:

For exterior walls a non-corrosive paper-backed lath is applied. All wood surfaces require the application of non-corrosive wire lath and a setting mix (between one-half to one inch thick) before applying natural thin stone veneer. Studs in walls are covered with exterior grade wood sheathing or cement mesh mortar units as chosen by builder. Minimum thickness of one-half inch is recommended.

 

Metal Lath:

For applications that involve installing paper-backed corrosion resistant wire lath: After the first piece of lath is correctly placed at the bottom of the wall, continue up the wall overlapping a minimum of three inches for each piece of lath from the bottom to the top. Wrap metal lath around and overlap at corners a minimum of sixteen inches. use self-furring, non-corrosive, expanded metal lath, 3.4 pounds per yard weight. Use Galvanized, barbed nails (or another quality anchor system such as galvanized screws and washers) at six inch vertical centers, in line with wall stud horizontal spacing. Place nails in furring groove or dimples to preserve quarter-inch furring away from wall of metal lath. Overlap horizontal joints of lath a minimum of one inch and vertical joints a minimum of one inch. A paper-backed metal lath can be utilized to avoid the need for a separate moisture control barrier being applied prior to the metal lath.

 

Thin Stone Veneer Installation Illustration

 

INSTALLATION PROCEDURES

 

Mortar Type:

Type N or S mortar is used for installing Natural Thin Stone Veneer depending upon the type of stone being installed. Either mortar type is compatiible with Capitol Products, Inc., natural thin stone veneer products. Our sister company, ESI Masonry Supply carries both types, as well as a great variety of masonry products and equipment.

 

Bonding Admixtures:

The use of a bonding admixture with the mortar may be recommended to add bonding strength (check with your stone dealer for recommendation). Please refer to the selected bonding agent instructions for recommended mixture quantities. Extra care should be taken when using bonding agents since dropping can be difficult to remove once they cure. The use of an epoxy, thin set and/or construction adhesives should only be used in interior applications. Admixtures are necessary for all soffit or overhead conditions.

 

Setting Natural Thin Stone Veneer:

Now that the metal lath and the scratch coat have been applied, installation of the natural thin stone can proceed.

  • If corner pieces are required for the application, it will be best to start with the corners first. This will provide a better guide for your pattern to continue around the corner.

  • Most corner pieces will have a long end and a short end. These pieces should alternate in opposite directions, as they are stacked, one upon the other.

  • The back of each stone should be covered 100% with a thickness of at least half inch of mortar. A bit more mortar can be added towards the center of the back of each stone.

  • The stone should be pressed firmly against the scratch coat wall to ensure a sound bond.

  • Extra mortar will ooze out around the edges as each stone is set in place. This extra mortar will fill in around the stone creating your grout joints.

  • If you choose not to use this method to fill the joints, then the joints can be filled with grout using a grout bag and/or a tuck pointing tool.

  • Make sure to create control and movement joints in the veneer in the same places that they exist in the structure. These control and movement joints serve to allow for the movement of the structure as it settles and moves from environmental changes. Consult a local contractor, your builder, or structural engineering professional to determine the need for these special joints.

Surface Preparation, Illustrations and Installation Guidelines courtesy Building Stone Institute (BSI).