QUESTION

we hired a local contractor to install a hardscape project for us. They installed approximately 400 square feet of 24 x 24 Landmark Ceramics porcelain tile. These were to be installed in a 4-foot-wide walkway. The contractor abandoned the project before it was finished. We have since found out the nothing was installed properly. This was to be a sand set installation. The wrong type and size of spacers were used, the substrate was inconsistent, not compacted properly and not even present in some locations. The Sure Bond Poly Sweep joint sand failed, and the Snap Track containment system was improperly installed and, in some areas, not at all. The tile walkway started to become loose almost immediately. Is it proper to sand set tiles?

ANSWER

Sand-setting tiles is not considered the best way to install ceramic or natural stone tiles, although it is done and has been done for many years and is normally less expensive than pouring a concrete slab and bonding the tiles to it. It is common for installing thick concrete interlocking pavers.  It is much more difficult to install the porcelain tiles in a sand-set method because they are so thin.  You have to use at least the 3/4" (2cm) thick porcelain tiles. Historically they would only install 1.25" (3cm) thick natural stone tiles or thicker in this method so they are less prone to damage.

The Tile Council of North America (TCNA) is working on developing an installation method for 2cm thick porcelain tiles, but there is not standard at this time.  The Natural Stone Institute does provide some information on sand-set stone installations.

It is the 2"+ concrete pavers that provide the best information for concrete paver installations. The Interlocking Concrete Pavement Institute (ICPI) is a good source for installing concrete pavers, but they don't necessarily apply to ceramic tile or natural stone. But their installation methodology would be a good guide for establishing a good base for a sand-set tile installation.

2cm Porcelain tile should never be recommended for a sand-set installation method that is subjected to vehicle traffic, because it is too thin and you can't achieve an interlock condition.

The proper way to install a sand-set installation base is to first grade the ground to the appropriate slope for the intended design and to make sure it will facilitate drainage away from the house to a drain. Compact the natural soil with a compacter machine.  Then apply a gravel road base material that is crashed rock and sand that is compatible.  In thinner layers put the gravel down and compact it with a compactor and building it up to the desired thickness. Use a metal screed to screed the base surface to be within the intended plane in a uniform manner. Residential foot traffic should be at least 4" thick.  For commercial vehicle traffic it should be at least 8" thick more more.  The finish surface has to be flat and within the plane of the sloped surface

Install a 1/2" of masonry sand over the compacted base and compact it with a compactor.  Add another 1/2" of sand loosely and beat the tile or paver into place.  Now compact the tile into place with a compactor so that the surface is flat and within the intended sloped plane.  you can't have any low spots where water can collect.  Fill the tile or paver joints with a masonry sand or a polymeric sand to hole the tile in place. It is critical that you pour a concrete footing along the perimeter of the sand-set installation that is about the thickness of the sand base and the tile or paver on top of it.  Normally you pour the concrete to the height of the top of the sand base and the adhere the tile or paver to the concrete footing so it constrains the tile to prevent it from pushing out when it is subjected to foot or vehicle traffic.

For a 2cm porcelain tile to work well on this application, everything has to be perfect.  You cannot have any voids under the tile or it will break.