Scratch Coat:
When required, a sand and cement mortar mix will then be applied over the metal lath, as thin as possible, but making sure that the lath is completely covered and SURFACE IS LEVEL. Scratch up the plastered surface while it is still wet using a leaf rake, hand rake or mason’s scratcher, so that the surface is not too slick or smooth. Most codes require the coat to dry 48 hours before applying stone.

Remember: Too much mortar can cause slipping!

NOTE: When installing Random shaped stones (as in River Rock or Split Fieldstone) apply approximately 3/8″ to �” of mortar to the entire back of stone. Another option is to apply enough mortar to middle of stone so that when pressed in to position you will have approximately 5/16″ to 3/16″ of mortar on back side. Slipping and sliding of stones occurs when too much mortar is used. This is acceptable as long as you work stone into place pushing out excess mortar.

Applying the Stone to the Wall
Depending on the type of stone, you will begin at either the top or bottom of the wall.

Push the stone firmly into place and “wiggle” the stone slightly to set the bond. YOU SHOULD PUSH FIRMLY ENOUGH SO THAT THE MORTAR IS SQUEEZED OUT AROUND THE EDGES OF THE STONE. If sliding or slipping occurs, the mortar may be too thin, you may be using too little mortar, or you may be using too much mortar. Also, if your are using thin-set, you could be using too much.

Applying Mortar to Large Stones – When Slipping or Sliding Occurs
If sliding or slipping occurs the mortar may be too thin or you may be using to little or too much. Larger stones will hold better if mortar is placed on all edges and a spot in the middle. This technique creates a vacuum which holds the stone in place until mortar sets which will  for better adhesion.

In general, if you have the right mortar consistency and the surface is properly prepared, you should only need 3/8″ to 1/2″ of mortar covering the entire back side of stone.

There are several methods of applying mortar to back of stones, but the end result should enough to have some mortar squeezing out of grout  3/16″ to a 5/16″ of mortar on back of stones if you checked it.

Deciding how to PLACE THE STONES ON THE WALL:
When applying stone with a grout joint, place it on the wall 1″ away from the grout joint and wiggle it back and forth sliding it into the desired �” grout joint. Click here for Grouting.

Grouted vs. Drystacked
Most of Coronado’s products can be either Dry Stacked (no grout joints) or Grouted.

Products such as Country Castle (that are recommended to be grouted) are manufactured in modular sizes to compensate a �” grout joint.

Example of actual height sizes of Country Castle are: 1�”, 3�”, 5�” 7�”

Coronado recommends applying the stones using a 2 stones off of one stone ratio rule for the “ashlar pattern.” as shown below:

Coronado’s Belgian Castle is made to be Drystacked (containing no grout joint). These stones are manufactured with even numbered heights including 1″  2″  3″  4″ etc.

          Drystacked (no Grout Joint) –

The mason’s goal is to minimize long vertical or horizontal grout joints. A general rule of thumb is that vertical grout joints should not be higher than two small stones or one large stone. Horizontal grout joints should not exceed 4 to 6 feet.

Coronado’s stones that are manufactured to be “dry stacked” can be grouted. Alternatively, stones manufactured to be grouted can be dry stacked.  The consequence of grouting stones that were meant to be Drystacked are narrow and loose joints because the joints have not been allowed for like in Belgian Castle.

The above picture shows the problem of aligning the top and bottom joints when grouting stones that were manufactured to be Drystacked. Fig. B is an example of how to correct this problem by using the “2 on 2” ration pattern.