Before I discuss the pros and cons of rodding, let me define the term. Rodding is the insertion of a metal rod into stone to provide apparent strength and to avoid breaking during transportation. The rod is inserted into a grove that is cut out in the bottom of the stone.
The controversy with rodding is whether it really provides strength or if it actually weakens the stone. I spoke to a number of fabricators and found that some rod every one of their granite countertops while others never rod. I also conducted a phone survey and asked numerous fabricators for their opinions on the matter. The following is a brief list of what I learned.
Pros And Cons Of Rodding
Provides strength to granite countertops.
Difficult to break.
Weakens the stone.
Provides a weak point leading to cracks.
To find out if rodding provided additional strength I conducted a crude experiment of my own. Two strips of 2 cm granite were cut into a length of 44 inches by 2 inches. A slot was cut in one of these strips and a long 1/8 X 1/4 inch rod was inserted and epoxied. The rod was inserted on edge so that the 1/4 inch side was vertical. The unrodded strip was placed across two 4” x 4”s. A flat, thin metal plate was placed on the center of the granite to serve as a point load. Weight was placed on top of the metal plate until the granite broke. This procedure was repeated with the rodded strip. The results were interesting. The unrodded granite broke at 80 lbs., while the rodded piece never broke, but developed a crack at 120lbs. I repeated this experiment three different times with similar results.
I also spoke with the technical director of the Marble Institute of America and he told me that the MIA is currently conducting tests on rodding and a paper will be published once the study is complete.
It is important if you do rod that you use the proper procedure and the right type of rod. The following procedure was submitted by Keith Graves of HE Saterwhite in Richmond, VA.
Considerations. The stone must thick enough to accommodate the rod without requiring a cut more than one half of its thickness. The stone must also be non-translucent, in that a rod and adhesive will not show through the exposed face.
Preparation. Sometimes it may be necessary to lay out and rod a slab before cutting it into the desired pieces. If this is done you must lay out the slab using extreme caution – allowing for blade thickness, cracks or other imperfections you plan to avoid.
Rod. The most widely accepted rod is a 1/8 in. x 1/4 in. stainless steel flat bar. The rod should be inserted on edge (with the 1/4 in. inserted as the depth or the thickness).
• After cutting the stone to size, layout the piece for additional cutouts such as sinks, cooktops, faucets, outlets, notches, and other cutouts.