QUESTION

Can I eliminate the grout joint (butt joint) limestone tile? I am now faced with a situation that i am about to start the Mockup of the flooring, and the consultant is asking to execute the work with zero joints. The Consultant believes that since we are providing 6 mm control joints every 5.4 meters, it is not required to provide any joints between the stone tiles. I explained to him of the stresses that will buildup, inability to grout properly, edge chipping, MIA extract showing their recommendations etc. He refuses to take anything into account. He wants me to provide him with a CODE (not recommendations) that says a x mm joint is required. I personally believe that even the 6 mm control joint is not enough and that a minimum 2 mm joint is required.

The application is 20 mm limestone flooring fixed with 5 mm CBP Marble & Granite Fortified Mortar on screed surface over concrete slab.

Do you have any documentation or ideas that will solve this issue ?

ANSWER

ANSWER - You are correct that there should be grout joints between the stones.  The purposes of grout joints are to allow for adjusting for irregularities in the sizing of the stone, to provide support and adhesion along the edge, and it does provide some degree compressibility between the joints.

The 2010 MIA Design Manual for Dimension Stone under Horizontal installation of stone tile Page 14-2.4.1.2 states joints should be a minimum of 1/16"  (1.6mm) and preferably 1/8" (3.2mm) . Joints of 1/4" (6.4mm) wide or larger are frequently required for larger unit size installations.

The 2011 Tile Council of North America Handbook for Ceramic, Glass, and Stone Tile installations says:  "The minimum required joint width for ceramic tile and natural stone tile is 1/16" (1.6mm).  Setting ceramic or stone without a grout joint of at least 1/16" (1.6mm) , often referred to as a butt joint, does not provide sufficient accommodation for dynamic building movement, differential thermal expansion, or allowable variation in fabrication of manufacturing."  If necessary, you can retain our services to assist you in this matter.  For more information visit our website at www.CTaSC.com