50% or 33% Offset? It’s now in the Handbook!
Much of the beauty and versatility of installed tile lies in the ability to utilize patterns to create an interesting effect. Today, with the popularity of rectangular tiles, the pattern of choice has been the 50% offset or brick joint. While this pattern can be very attractive, it can also be frustrating when the inherent warpage on the long side of the tile causes lippage.
This lippage issue many times leaves the installer with a difficult if not impossible task, when a 50% offset with a credit card or 1/32” grout joint is specified. The problem occurs when the high point in the center of the long side of the tile is placed very tightly next to the two low point abutting tile ends.
Until last year, the installer had little or no support in finding a solution to this situation. Now both the ANSI Specifications and the TCNA Handbook include language that will help installers overcome the concern of tight grout joints and the offset pattern. For this article, however we will concentrate on the offset pattern and leave the grout joint for another time.
Page 27 of the 2012 Handbook speaks to the topic of this pattern. 18.104.22.168 Running bond/brick joint offset: For running bond/brick joint patterns utilizing tile (square or rectangular) where the side being offset is greater than 18” (nominal dimension), the running bond offset will be a maximum of 33% unless otherwise specified by the tile manufacturer. If an offset greater than 33% is specified, specifier and owner must approve mock-up and lippage.
By moving the intersection of the two ends of the tiles to the 33% location from the 50% location, the lippage is significantly reduced and most times provides an acceptable appearance. Many tile manufacturers now recommend that their products be installed with the 33% offset which further supports tile mechanic’s need to install a tile pattern that will be satisfactory. The Handbook language also gives the installer a method to overcome being responsible for the possible lippage by requiring the specifier and the owner to approve it prior to starting the Installation. This is a win-win situation for all involved.
The photo illustrates the beauty and functionality of the 33% offset. Use this specification to your advantage. When a job calls for an offset installation, go for it, because now you have the support you need.