Otherwise you need to install the backup strip with the ASTM C920 sealant over it.Įxpansion joints is a type of a movement joint as described in TCNA Handbook detail EJ171. It can be left open if there is a tile base going over it. Exterior and Interior applications subject to direct sunlight are to be placed every 8 to 12 feet in each direction.īe sure to include movement joints at all the perimeters, change of plans, and where you are tiling up to restraining surfaces. They should be installed very 20 to 25 feet in each direction for interior applications that are not subject to direct sunlight. It should be tooled to achieve a slight recess so the foot traffic doesn’t touch the sealant. The joints are suppose to have a compressible closed cell back up strip with an ASTM C920 Traffic Grade sealant. It is not uncommon for the movement joints go straight across, which would be more practical if the movement joint extends into the mortar bed if this is a mortar bed installation. The TCNA EJ171 now allows for zipper or sawtooth generic movement joints in tile installations, where you follow the grout joints within the tile assembly, not into the mortar bed.
