How to install ceramic floor tiles next to wood flooring
by Jim Bessey
Ceramic tile floors form a natural complement to hardwood floors. The trick lies in how you transition from tile to wood. Since the two materials are so dissimilar, they expand and contract at very different rates. You should never simply butt new tile to an existing wood floor, or vice-versa. Let's look at the two most common scenarios.
A. Your new tile floor will be nearly the same height as the existing wood floor:
This occurs fairly often, since hardwood floors are generally 3/4" thick. Floor tile is often best laid over 1/2" cement board; add tile that's about a quarter-inch thick, and the two floors will be nearly equal. In this case you'll need some sort of simple expansion joint.
Product choices:
Most home centers carry a nice assortment of Schluter brand transition strips designed for this purpose. You can usually choose from plastic (in colors), aluminum, or brass. Brass is the most durable and most expensive, and sometimes considered a bit gaudy. Plastic is inexpensive and by nature more susceptible to wear; but the choice of colors allows for some designer creativity. Aluminum falls between the two.
Viewed from the end, these strips all present a simple L-shape, with the short leg facing up. The longer, thinner leg is installed just beneath the tile. Choose a short-leg height that most closely matches your tile's thickness (take a sample along to check this).
Installation method:
Transition strips are laid after the tile underlayment is complete, and before you set the row which will finish the tile floor as it meets your existing wood floor. To allow for expansion, leave a gap between the wood and the Schluter strip of about 1/8". It's best to use some sort of spacers to set this gap, although you could certainly do it by eye.
These edging strips also include a tiny "bumper" on the tile side to provide proper minimum spacing for this final row of tiles. You can increase this space to better match your chosen grout-joint size, if you like. Complete your tile project by grouting up to the inner edge of the transition piece; use masking tape to protect the hardwood.
Once the grout has cured for a day or two, finish the job by adding a bead of silicone-based caulk between the edging strip and the wood floor. This caulk can be clear, translucent, grout-matched, or of a color to complement the wood itself. Your tile supplier will have each of these choices available. Remember the rule of caulking: use half as much as your think you need, the first time. It's much easier to add a bit more than to clear away a gooey caulk mess from overfilling.
B. Your new tile floor will be significantly higher than the existing wood floor:
This happens quite often, given tile's requirement for heavy, solid underlayment. Many wood-slat floors, typically of oak, are only 3/8" thick. It's not at all advisable to lay tile to match this thickness - you'd have to omit the underlayment entirely, not a good idea!
Another common reason for a tile floor that's higher than wood is that you'll be covering up a portion of an existing hardwood floor by laying tile over-top. This is done to create a traffic-friendly foyer area where your front door enters directly on a wood-floored room.
Product choices:
In the first case, where your new tile floor will end up between 1/8" and 1/2" higher than the hardwood, use an approach very similar to the one outlined above, for equal-height floors. You can use the same L-shaped transition strips, and expose the wood-side edge more completely.
There are, however, a couple of additional profiles you can consider to ease the transition. The larger the height difference, the more this matters. Two different styles of metal "ramps" are commonly available, depending on the height to be spanned. Viewed on edge, these ramped transitions look like an arrow split down the center lengthwise. Since these strips hide the expansion joint, you won't need to add caulk. Just be sure to leave the same 1/8" gap between wood and metal.
Installation method for higher tile floors:
For tile-over-wood you'll use a slightly different tactic. First, be sure the underlying wood floor is solid and not squeaky. Use screws or nails to re-secure the wood floor into the floor joists below to eliminate squeaks. Since these will be hidden, cosmetics don't matter. If you use screws, be sure to countersink them.
Next, add a thin cement underlayment (not lauan!). The standard thickness for this purpose is 1/4 inch. Be sure to follow the manufacturer's instructions carefully, since this product is less able to span bumps or surface irregularities. It's also important that you carefully mark, measure, and meet your new floor's edge-point. This is even more critical if you're creating a mitered outside corner for your new tile floor (a common situation).
When you continue by installing floor tiles over the new sub-floor, your tile floor will be no less than 1/2" above the surface of your existing wood floor. This is quite a "bump" to negotiate. To soften the step-up, use the same Schluter transition strips mentioned previously, but add one more step - a sloped wooden transition ramp.
Adding wooden ramps:
Wooden ramps are available from flooring dealers and some home centers. Various thicknesses and widths, as well as wood species, are offered. You can either rise all the way up to the height of an L-shaped tile edge, or split the difference by using both a wood and metal-edge ramp.
As an example, if you're trying to span a 3/4" jump in floor height, you could use a standard 3/8" by 2" wood ramp first, then add a standard 3/8" brass Schluter ramp on top (using the method described earlier for metal ramps). The alternative is to purchase a full-height 3/4" by 3" (approx.) wood transition, butted to the Schluter-L strip - with the previously-described expansion joint.
Of course, you'll want to match the species of your wood floor as well as possible, and then stain and finish your new wood ramp to mimic your existing floor's finish. Use a premium grade floor urethane for durability.
With careful planning and attention to detail, you can allow your new tile floor to peacefully coexist with your original wood floor. Your transition will be strong and aesthetically pleasing, while it protects your new tile from edge damage. Done properly, your tile to wood transition will last as long as either of these highly durable materials, and look great the entire time.