Tile How-To: >> Countertops (New Installation)
This section will detail the tiling process in a photographic step by step format. Keep in mind what you have learned from previous sections concerning the choice of tile, layout considerations, and desired methods. Also, remember to follow the Manufacturers instructions for the products that you choose to use.
Mortar Bed
The following series of photographs will detail one method used in tiling residential bath and kitchen countertops using the mortar method. Note that in both applications, the backsplash tile was applied directly to drywall using a type 1 mastic adhesive. Also, both applications utilized self-rimming sinks.
The cabinets and ¾" exterior plywood tops were installed by the Manufacturer. The cabinets and tops were checked for adequate fastening by inspection and pulling on the cabinet faces.
They were also checked to insure that the tops were on plane and level.
The sink hole was established by using the Manufacturers template centering the sink in the appropriate cabinet. While centering the sink, insure that the tile layout will provide as full of tile as possible for the installed sink to rest on.
Prior to the application of the 15 pound roofing felt, dot and dash cuts should be made in the plywood 6" on center with the plywood grain to equalize moisture above and below the plywood. 
This step is especially important if dishwashers or other moisture producing appliances are to be installed.
The "craft" type paper is installed to protect the cabinets below and then the roofing felt.
The roofing felt needs to be folded tightly into all corners and should extend up the adjoining walls beyond the eventual mortar bed depth. Tape the felt to the adjoining walls to protect them and to keep the felt out of your way during the mortar process. Use a tape that can be removed easily.
Remember to leave the felt in place over the sink hole and mark the opening with chalk or a grease pencil. This keeps the mortar from falling through the hole during the mortar process.
The lines drawn on the felt allows the installer to place the wire mesh flush with the intended opening making the mortar installation easier later.
The 2.5 pound minimum reinforcing fabric is installed either before or after the cap strip. 
The reinforcing mesh is fastened with ½ or 5/8" staples in a 6" grid pattern through the felt into the plywood. When there is no wall mortar above the deck mortar, terminate the reinforcing wire just short of the adjoining walls.
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Dr's Tip: If the walls are to receive mortar, terminate the reinforcing wire at a point even with the intended wall mortar and tile thickness. This will help prevent any cracks from forming in the finished deck or wall tile. |
The cap strip is installed in this case with 1 ½" galvanized screws through the felt and "craft" paper. Loosely hang the first cap strip with one screw or nail making sure that the bottom of the strip is approximately even with the bottom of the deck plywood. This will make the eventual mortar bed nearly one inch thick.
The bath counter in this case will receive a tumbled marble apron tile made by cutting the 4" tile in half. This apron will cover the finished mortar bed and mortar filled cap strip later. If the intended apron or V-cap trim will not cover the mortar filled cap strip, adjustments must be made.
Once the installer is satisfied with the placement of the cap strip, the cap strip is leveled and fastened securely every 6" of its length. This process is repeated around the cabinet leveling the with each other.
The first batch of mortar is mixed like wall mortars (1 part Portland cement, 1 part lime, and 7 parts damp sand). In this case, the mortar was mixed in a wheelbarrow.
The dry ingredients are mixed first and water is added to bring the mortar to a workable consistency where a furrow made in the mortar will not collapse.
This mortar is used to fully imbed the wire mesh in mortar, to surround the sink opening, to imbed the pencil rod (if used), and to fill and back up the cap strip.
Imbed the wire mesh by forcing the wall mortar into the mesh using a finish trowel. Pack the sink opening well above the intended mortar finished height.
Pack the rear of the cap strip with the wall mortar at a 45° angle to the deck, then fill the front of the .
This process is accomplished with a finish trowel and margin trowel.
Cut the excess mortar off the front of the strip as you go.
Next, use the wall mortar to set the float strips (if used) the desired finished level of the mortar bed. Columns of mortar are place at points that will allow a screed to reach from the cap strip to the rear of the mortar bed.
The float strips are leveled with the cap strip. It is a good idea to insure that the float strips are level to one another so that the rear or the deck remains level and on-plane during the mortar process.
Since wall mortar is pliable, dust the columns of mortar with dry cement after the float strips are in place. This will firm up the columns of mortar helping to resist movement during the rest of the mortar application.
Next the deck mortar or "dry pack" is mixed (1 part cement to 4 parts damp sand). Again the ingredients are mixed before the water is added.
Deck mortar needs only enough water to bring it to a consistency that the mortar will clump and hold together in the hand leaving very little moisture behind.
Then deck mortar is installed on the deck and is firmly packed in place with a combination steel or wood trowel and screed. In this case a short level is used as a screed.
The packing of the deck mortar has resulted in the mortar and process being called "dry pack."
Once all the areas of the deck has been packed and finished, the float strips are removed and their recesses are filled with mortar.
The decks then receive a final rub and check for any depressions or voids.
In this case the decks were allowed to cure until the next day (minimum 20 hours at 70° F).
The layout for the bath counter worked best with full tile at either end of the counter, meeting at the 22 1/2° angle where the two cabinets came together. Layout lines were established and all the cuts were made prior to any adhesive application. This made the tiling process faster and easier later.
Latex modified Portland cement thin set was applied to the deck in a manageable area that could be tiled before the thin set could "skim over." In this case the tile was started at the angle cut and advanced in one direction at a time.
A ¼" notched trowel was used at a consistent angle slightly less than 45° degrees insuring nearly 100% coverage on the back of the tile.
This was verified by lifting out several tiles during the process after being beaten in. A rubber mallet and beating block was used for this process.
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Dr's Tip: On countertops, a beating block is especially important, as the surface needs to be especially on plane for appearance and function. |
It is important to keep the tiles that form the leading edge of the counter straight during the process. Use a straight edge to keep them straight and also flat. This is also true of the tiles that will support the sink a level or similar straight edge placed on top of the sink supporting tile then lightly tapped will work nicely.
Once the field tiles are set, finish the job by setting the backsplash tile and apron tile. Remember that the 90° joint at the deck and backsplash should be filled with a sealant not hard grout. While the apron tiles were set with thin set mortar, the backsplash tile was set with type 1 mastic.
In this case a ledger was used to set the apron tiles. The ledger consisted of a ¾" board set below the apron to support the tiles while the thin set cured. The board in this application was screwed to the cabinet face, as these cabinets were to receive a painted finish. In the case of stained cabinets, use clamping devices.
Once the tile has cured, the grout was mixed and installed according to the Manufacturers instructions. The grout is forced into the joints using a rubber grout float held at a 45° angle diagonally across the tile face. The excess grout is cut off using the same float. The grout joints are tooled with a quality grout sponge thoroughly wrung out of excess water. Finally, the final wipe diagonally across the tile face.
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Dr's Tip: Always try not to overwork the grout joints. The minor haze in the process can be wiped clean after the grout cures. |
Finish the job by following the Manufacturers curing instructions. In this case the instructions were to mist the joints for three days following the grouting job. This was accomplished by using fresh water in a household spray bottle with the nozzle adjusted to a fine mist.
The principal difference in the bath counter and the kitchen counter was the addition of a pencil rod in front of the sink opening. This was especially important as this cabinet has a pull out tray feature below the sink for small household sponges and the like.
The pencil rod was placed in the middle of the mortar bed in the early mortar process. Wall mortar was used for its placement.
The other difference was that a v-cap trim was used instead of an apron.
The best layout for the kitchen application included a diagonal full tile bar and soldier course tiled main deck area.
The marble mosaic specialty tile was applied directly to the drywall using a type 1 mastic. By careful measurement the tile in the backsplash resulted in a full tile layout.
BACKERBOARD
Porcelain, ceramic, and stone tile can be installed on countertops using the many backerboards on the market today. Simply said, the backerboards essentially take the place of the mortar bed seen in the preceding section. Review the COUNTERTOPS section for more details.
The critical elements in the use of backerboards in countertops installations are that the cabinets to receive the tops must be level and on plane with no deviations exceeding 1/8” in 10 feet. This is due to the fact that the plywood and backerboard will follow any imperfections in the framing below. If there are imperfections in the cabinets, these imperfections will show in the tilework.
The other element is that the installer should follow the manufacturer’s recommendations the use of the chosen backerboard product.
Remember that countertops, especially kitchen and bath, are exposed to water intrusion. This may mean that some type of water resistant membrane should be used either between the backerboard and plywood base or between the backerboard and tile. Some backerboards are water resistant and may not necessarily need this layer. However, the exposed plywood at sink openings and cabinet face should be treated with some type of liquid or trowel applied waterproofing.
The installation is similar to mortar beds in the early stages. The cabinets are checked for secure fastening, level and on-plane. The height is checked for satisfactory clearance of all intended appliances and opening and closing of drawers and doors.
The face of the existing cabinets are protected with paper or plastic sheeting and a ¾” (23/32”) exterior grade plywood base is installed over the cabinets and fastened securely with 2” deck screws or their equivalent 6” on-center. The plywood should receive the same 6” to 8” on-center dot and dash cuts through the length of the plywood to prevent warping.
Only plywood can be used for the wood base in backerboard installations because the backerboard needs to be fully supported. This is a departure from mortar beds where individual boards can be used under the mortar bed.
Any cantilevers or overhanging counters (bar eating areas) should be well supported with framing to prevent movement.
This is the area that gets a little complicated. Backerboards should have a bed of freshly combed thinset beneath them. A countertop is similar in this respect to backerboards installed on flooring. The thinset bed insures that no air pockets remain between the board and the plywood.
Some manufacturers recommend that a waterproof membrane be installed over their backerboard. Still others recommend that it be installed between the plywood and backerboard. Some others have no recommendation. The issue is that recent changes, according to the Tile Council of America 2003-2004 Handbook, indicate the need for a water resistant membrane in countertop installations.
If a typical membrane like 15lb roofing felt were used, the felt would interrupt the advantage of the thinset layer. Hence, it might be a good idea to use a liquid applied membrane if one was to be installed under the backerboard. Again, follow the manufacturer’s recommendations.
The backerboard is then installed in a freshly combed bed of thinset and fastened in a grid pattern using approved corrosion resistant nails or backerboard screws 6” on-center. A 1/8” gap is left between sheets for a joint to be filled later with thinset and alkali resistant tape. An apron of backerboard is cut to 1 ½” to 2” (depending on tile v-cap or trim size) and laminated to the deck backerboard and plywood.
Experience tells us that pre-drilling 1/8” holes in the apron allowing 1 ½” roofing nails to securely hold the apron in place against the plywood and deck backerboard works especially well. A 2” or smaller backerboard apron fractures easily when being screwed or nailed.
Next the joints are filled with thinset and alkali resistant tape is embedded into the joint thinset then smoothed to a consistent joint with the flat side of a notched trowel or finish trowel. Try not to make these joints high. Keep them as close to the backerboard height as possible.
The joint made by the application of the apron piece receives tape and thinset also in an attempt to make the apron and deck backerboard monolithic or simply as if it was one piece.
The splash wall can receive backerboard also or tile can be set directly on the drywall, plaster, or existing masonry.
Once the backerboard has cured per the manufacturer’s recommendations, tile can be set, normally using modified thinset, and grouted in a like manner to the installation earlier in this section.
PLYWOOD
Porcelain, ceramic, and stone tile can be installed on a plywood base also. The process is similar to that of backerboards with a few cautions. Essentially, the upper plywood layer takes the place of the backerboard layer.
The cautions are obvious and deal mainly with water intrusion which can affect the plywood under the tile. This means that a plywood base may not necessarily be the best choice for countertops in areas that will receive hard use and lot’s of water like kitchen counters used everyday. It is a good idea; therefore, to waterproof the upper plywood layer with a liquid applied waterproof membrane prior to setting the tile in areas that are likely to have water used on the surface.
Again, follow the manufacturer’s instructions for the products chosen. These instructions are mainly found within the adhesive selection. Certain thinsets designed for use on plywood, organic (mastics) adhesives, and epoxy’s can be used in these installations.
The steps are nearly identical for backerboards in that the plywood will follow the level and on-plane of the cabinets below. Therefore, the cabinets need to be level and on-plane within 1/8” in 10 tolerances. The first layer of 19/32” exterior grade plywood should be securely fastened and dot and dash cuts performed.
The height of the first layer must be confirmed and adjusted if necessary to accommodate appliances, fixtures, door/drawers opening and closing, and to fit the tile trim at the apron interface.
For the second layer, ¼” gaps should be left between successive (19/32” exterior grade plywood) sheets to allow for expansion and contraction. These joints should be treated per the adhesive manufacturer’s instructions. The upper layer of plywood should be fastened securely in a similar way as backerboard using corrosion resistant fasteners on a 6” on-center grid pattern.
| Dr’s Tip: Some manufacturer’ may recommend that the joints be filled with the setting adhesive while others may want the joints left open. This is accomplished with the use of tape applied over the joint under the adhesive layer to prevent the adhesive from entering the joint. |
Again, cantilevers and overhangs must be fully supported to prevent movement.
Once the plywood decking is in place, tile can be set in place. Of course a decision must be made concerning the setting of the splash, if any.
