Selecting and Installing Ceramic Tiles - April 10th 2002



You can use a floor tile on walls, but rarely are wall tiles strong enough for floor use.

The strength of quality of a ceramic tile usually plays a large part in determining the selling price. Less expensive tiles are often of poorer quality.

“First Quality” means the manufacturer has sorted his product, and you are getting the top selection.

“Seconds” usually means minor imperfections, but are usually a minimum of 25% cheaper. These imperfections can be warpage, pin holes in glaze, colour problems, or weakness in the strength of the glaze or bisque.

The “Rating” of the glazed surface is important when choosing floor tiles. All manufactures should rate their glazed tiles.

A) a “1” rated glaze is for wall applications only.

B) A “2” rated means the tile can be used on very light floors only. Should be restricted to bathroom floors and bathroom counter tops.

C) A “3” rated glaze tile is the normal residential floor tile.

D) A “4” rated glaze tile is stronger and will wear longer.

“Non-Slip” finishes are available on floor tiles. The cost difference for this special coating is usually very little. Anti-slip coatings are recommended for all floor areas where standing water is possible: entranceways, front steps, or around bathtubs and showers, for example.

Ceramic Tiling Tub Enclosure

The Backing Material

In installing ceramic tiles on the walls above a bathtub, it is very important that the support walls (studs) are sound, with cross members at the tope of the tub and behind the taps to form a solid back up.

It is very important to have support “stud” horizontally as well has vertically, where there will be joints in the wall panel material. A properly constructed cement mortar wall is the best back-up possible, but requires special skills and understanding in its formation. Gyproc is a poor material to apply tiles to, in a wet area such as a tub splash, but is still regrettably widely used.

Water resistant gyproc is a slight improvement, but construction panels such as Wonderboard are far superior. As a minimum, in regard to costs, a band of Wonderboard or similar material (not affected by water) should extend about 18 inches up from the top of the tub. This will substantially reduce the potential for bond failure due to water damage.

DO NOT USE PLYWOOD, water can swell and warp this material, leading to cracks in the joints causing deterioration of the life span of the installation.

The Area Between The Tub and Backing Material

Most bathtubs have a lip or flange (app ¾”) that is used to secure the tub to the wall. The normal procedure is to secure the tub, and then start the paneling from the top of this lip, not overlapped to the edge of the tub. If the paneling is overlapped, this causes a slight curvature to the bottom of the wall, which does not look as nice, especially in the corners.

If the gyproc is to be used and is lowered past the top of this lip, moisture problems are likely to occur as gyproc has tendency to absorb or wick water into it, causing swelling and disintegration. When the paneling is stopped at the lip, it should definitely have a horizontal stud behind it to nail it. The gap (approximately ¾” by approximately 3/8”) should be filled with a thin – set mortar and smoothed off, extending the wall to the tub.

Planning The Layout

The first step in starting your installation is to use a level on the tub and walls to determine the state of trueness.

Starting from the low point on the tub deck, “walk” your tile (using two tiles) from the deck, up about 18 inches and make horizontal level line on all three walls. Next, make a level center line (vertically) on the back wall from the deck to the top row.

Note: the vertical centerline may be moved if the tiles end up with small cut in the corners. Check by laying a row of tiles along the tub, starting from the centerline. It does not look professional, if there is a full tile in one corner and a small piece in the other.

Caution should also be taken to allow for walls that are not straight up and down. If the tiles in the corner are to be cut from top to bottom, errors in the straightness of the wall are not as noticeable. If the side walls require cutting of the tiles, it is much nicer if the cuts are in the corners, on the front edge.

If you wish to extend the tiles, past the tub to the floor, the pieces of tile should be no smaller, so there won’t be any unpleasant surprises after it is too late.

Applying the Tiles

Using the correct notched trowel recommended by your tile store for that particular tile, apply the bonding material (thin – set mortar or water resistant mastic) to the back wall. Cover an area two to three rows horizontally at a time and begin applying tiles, starting at the intersection of your two level lines. Be sure to space the tile 1/16 to 1/8” apart to allow for grout.

Some bonding materials “skin over” quicker than others, caution should be taken to avoid spreading the bonding material too far ahead of you.

Do not “butt” the tiles in the corners or along the tub, but leave a grout joint width showing, to be filled later with silicone. When you have put the tile onto the glue, twist and tap tiles into place and use a level every few rows, as you proceed up the wall to ensure everything is maintained straight and level.

Once the back wall is in place and the soap dish is placed where desired, start your side wall from outside level horizontal and vertical lines and run your first row to join the back wall. This will ensure the side wall lines up with the back wall, then fill down to the deck, cutting out tap holes as close as possible to ensure they can be covered with the cover and sealed later with silicone.

Waterproofing The Corners

Your tile installation at this point, should have a 3/16 to 1/8” gap up the corners and all around the tub and tile intersection. The gap should be filled with approved anti-mildew silicone, to act as an expansion joint. Hot and cold water on the tile surface and vibration, due to outside sources, etc. can cause the grout to crack, resulting in potential water damage.

Note: Tub should be full of water when you caulk around the joint between tub and tile

The expansion material can be applied before or after grouting. Use masking tape to keep the joint sharp. Silicone should not be applied on the top of grout or on top of the surface of the tile.

Installing Interior Ceramic Tile Floors

It is very important that the under surface that you are tiling over be sound construction. Movement in the under surface can cause tiles and grout to crack and spoil the appearance of your floor. The stiffer the floor the better. Extra pony wall s or braces under the floor or the addition of an extra layer of material on top of the existing surface can reduce movement.

During new construction you should consider floor joists on 12” centers instead of 16” centers on areas where you plan to install ceramic tile floors. Double layering of plywood floors is also highly recommended to stop the potential of cracking.

Laying The Tile

Plan your layout before beginning to lay the tiles down Remember that often your walls are not completely square. Concentrate on the focal points sin the room and place full tiles in these areas. Cut tiles will be much less noticeable along cupboard edges etc.

Liquid latex additives are available to add to thin set mortar mixes to make the installation more durable. Epoxy ceramic tiles adhesives are also available. They are stronger but more expensive. Whatever type of adhesive you are using, do not skimp on the coverage. Trowel a thin coat onto the floor surface and cover the back of the tile completely with adhesive mortar, do not leave any ridges. There should be 3/16” of adhesive mortar between the tile and the floor surface. When placing the tiles on the floor, do not push the tile too hard or you will force the bonding material out around the edges.

Installing Ceramic Tiles Outdoors

Ceramic tiles for outdoor use must be frost proof, able to withstand the stresses of freeze thaw conditions. When you are purchasing the tiles, make sure to ask if they are suitable for outside use. Non frost proof tiles can delaminate with changing weather conditions. If the tiles are on a walking area, paths, steps etc. be sure to choose unglazed or slip resistant surfaced tiles. Unglazed quarry type tile do not require sealers to finish the surface. Sealers can become extremely slippery and dangerous when wet.

Do not install outdoor ceramic tiles on any type of wooden material. When plywood gets damp it will expand and easily cause tiles to come off. Install tiles on concrete, masonry surfaces or special cement boards for exterior applications. Make sure the surface is clean and dry before applying the adhesive.

Ready-made adhesives should not be used for ceramic tiles outdoors. Cement based acrylic thin set mortars will work best. When applying the bond material complete coverage is important. Any air voids between the tile and the surface can fill with water and potentially freeze causing a bond failure. Mortar should be completely cover the surface, and then completely cover the back of the tile ending up with about 1/8” of mortar between the two surfaces.

Grouting Ceramic Tile

Grout is the product used to finish the spaces between the tiles. Cement based grouts are most commonly used for residential installations. There are three general grades of grout.

UNSANDED: usually for walls – maximum 1/8” joint widths
SANDED GRADE: used for 1/8” – ¼” joints
QUARRY GRADE: uses coarser sand for joints in excess of ¼”

The two sanded grades are slightly rougher but are substantially stronger and must be used for floors.

Grout should not be applied for at least 24 hours after the tiles have been laid. Clean the surface of all debris and protruding bits of bonding material.

The cement in grouting material is what makes it hard and takes a reasonable time to totally harden. If group dries too fast, the hardness can be reduced. To improve the resulting grout, dampen (not soak) the joints between the tiles an hour or so before applying the grout. This can be done with a damp rag, brush, sponge, spray bottle etc.

Mixing the Grout:

When mixing dry powder grouts with water or a liquid additive, very little mixing is required to evenly blend the grout. Over mixing can entrap air bubbles, which may increase shrinkage, allow moisture to dissipate easier and can affect the overall uniformity of colour. To reduce air bubbles add the liquid to the powder instead of the other way around. DO NOT MAKE THE MIX RUNNY! Mix to about the consistency of peanut butter. Let sit for about five minutes then lightly remix. The use of latex additive when mixing group substantially improves the colour and surface hardness.

Applying the Grout:

1. Apply the grout into the joints with a rubberfaced grouting trowel or float. To prevent internal voids pack the grout into the joints. After the joints are full use the float to squeegee the excess grout off the surface of the tile and to level off the grout joints.

2. Let grout dry for about 15 minutes. Using a spray bottle spray a misting of water on the entire surface. Immediately use the float trowel and repeat the squeegee process to further remove surface grout and smooth out grout joints.

3. Let the grout sit about 30 minutes, then use a damp (not wet) sponge and lightly wipe surface of the tile. Do not use a circular motion with the sponge; use diagonal strokes so as not to disturb the grout lines.

4. Fine dust residue can easily be removed with a clean dry cloth the following day when the grout is hard and not subject to damage. Allow a minimum 12 hours to harden before further washing or in the case of floors, walking on them.

5. All cement-based grouts should be sealed to retain their appearance and reduce cleaning problems. Grout must be allowed to cure for a minimum of one week before applying a sealer.