Photo 1


Photo 2

About a year-and-a-half ago, I received a phone call from a gentleman asking for an estimate on re-sealing the grout in the ceramic tile on his exterior deck.  When I arrived to inspect the tile on the deck, I noticed that not only had the grout not been sealed properly – a great deal of the grout was missing.  In fact, most of the ceramic tile was not even bonded to the substrate.  I should mention that the size of the deck was approximately 22 feet wide by 77 feet long and included two flights of tiled stairs.  The floor drains were also a problem, not having the ¼-inch per foot slope required for proper water drainage. This also explained why a couple of large floor squeegees were leaning against the house.  Removing the drain covers, I discovered that the drainage pipe was only 1-inch in diameter.  The customer must have seen the concerned look on my face as he informed me the ceramic tile had only been down four years and that he knew we might have to re-grout some of the problem areas.  I told him I thought his problem was bigger than that. 



Photo 3

Upon further inspection, I could see that cementitious backer board had been used for the substrate over a ¾-inch plywood subfloor.  Unfortunately, the backer board did not have a bed of mortar under it nor did the joints show any signs of alkaline-resistant backer board tape.  I mentioned to the homeowner I could see no type of waterproof membrane installed either.  To this he commented that this must be why the drywall in his basement, which was directly under the deck, also needed to be replaced.

From this single inspection, the job the customer had called me about had gone from a simple re-sealing of grout to a total replacement job costing well over $60,000.  Although I have been in the floor covering installation trade for over 33 years and had been setting tile for 26 of those years, I knew better than to take on a job of this magnitude without the help and guidance of the manufacturers involved.  I was also fortunate to have a wealth of information available to me through my Certified Floorcovering Installers Association (CFI) associates – a service available to anyone who wishes to seek out their knowledge.  With products and installation procedures constantly changing, having an organization such as CFI that works diligently to educate and train installers on the most updated products and installation techniques available in the flooring industry is imperative.  Taking advantage of these resources gives any job a much better chance of success and long-term survival.



Photo 4

I am reasonably sure that most ceramic tile installers have done their fair share of interior tile jobs, but I am equally confident that few have done as many exterior tile jobs as interior.  While most think there’s not that much difference, which is most assuredly not the case.  The challenges faced are multiplied on an exterior ceramic tile installation.  Some of the elements that come into play include rain, wind, extreme temperatures (both hot and cold), sap and leaves from nearby trees, and bird droppings – just to name a few.  It’s always good to have great mortar coverage under the back of the installed tiles.  80% coverage is the required minimum for interior jobs, but at least 95% coverage is needed for exterior jobs which really should be bumped up to 100% keeping in mind the freeze and thaw issue.  Water gets into the voids under the tile and expands when it freezes, cracking and de-bonding the tile.

I wish I had “before” photos to share, but I don’t.  By the time I got back to start the job the building contractor had already removed the ceramic tile, as well as the backer board and the subfloor, and reworked the roof over the existing dwelling directly under the deck.  He had already installed a new subfloor, too.  Our original plan was to start at the house with the subfloor and allow a ¼-inch per foot slope to the outside of the deck and installing a mini-gutter.  This would have allowed us to eliminate the two floor drains and all of the plumbing.  Unfortunately, though, an I-beam was in the way, preventing us from doing so.  Instead, we were forced to install the floor drains using 3-inch drainage pipe instead of the 1-inch used previously in order to move the water from the deck much quicker.



Photo 5

There are several different methods which can be used to install ceramic tile on an exterior balcony or deck.  I chose the manufacturer’s system with which I was most comfortable.  Photo 1 shows the beginning of the chosen system, which starts no different than a typical interior application.  The building contractor has installed a ¾-inch thick plywood subfloor.  Now, the tile contractor must install the cement backer board units (CBU).  In some areas of the country, the building contractor installs the CBU for the tile installers, which in my opinion is not a good idea unless the contractor has had the proper training.  More often than not, the contractors have not had the proper training, which usually leads to some type of breakdown in the installation system of the ceramic tile.  For example, the CBUs must be laid out in such a way that the seams do not fall directly on top of the seams in the plywood subfloor.  The CBUs must be laid out in an offset pattern with a 1/8-inch gap between panels.  Extremely important, too, is to embed the CBUs in a bed of mortar that has been applied to the subfloor using a ¼ x ¼ -inch square notched trowel before fastening it down with the proper nails or screws.  Likewise, all the seams (the gaps between the panels) must be filled with the Portland-based mortar and alkaline resistant backer board tape applied.



Photo 6

The next step in the system is to apply the membrane (Photo 2), which in this case is an uncoupling, waterproofing, vapor management and support/load distribution membrane.  The photo shows that I have keyed in the mortar with the flat side of my trowel before combing the mortar in straight lines.  This is an important step that is often overlooked when installing products with thin-set mortar.  Using this procedure provides as much as a 50% better bond.

Photo 3 shows that the membrane has been installed with a waterproof band on all the seams and all the edges include flashing the band up the walls of the house with waterproof preformed outside corners on the rail posts.

The correct placement in the installation of thermal expansion and contraction movement joints (sometimes called “soft joints”) is critical, as shown in Photo 4.  Without the use of these movement joints, changes in temperature could result in tiles de-bonding and/or tenting, tile breakage, grouts cracking, coming loose, etc.  These joints need to be placed every 8 to 12 feet in both directions on an exterior application.  I chose to use a prefabricated, maintenance-free surface movement joint profile system, which is installed as the tile is set.

Movement joints must be placed at every abutment (Photo 5).  Note that the ceramic tile has purposely been cut a minimum of 1/8-inch shorter around the rail posts.  To allow for expansion and contraction (or movement), this void must remain free of mortar, grout, or any other hard substance.

Photo 6 shows the finished job.  Remember, the job is not finished until the maintenance is done.  Homeowners need to understand that this is not the time to skimp on the proper cleaners and sealers – this tile floor will be forced to deal with all the elements of nature and must be prepared to do so.