Tiling a screened porch: tiling preparation

Some Florida rooms have it, so do many lanais. Tiling enhances a screened porch by keeping the flooring cool in the summer, and in the early spring and fall, a small heater can transfer heat along the tiles to keep toes toasty. A screened porch can be easily tiled with just a few small steps taken to properly prepare the floor.
The main consideration in tiling a screened porch is to begin with an adequate base for the new tile. Preparation is the key to a quality finished job and to guarantee your tile will be a durable flooring for years into the future.

Preparation of the present porch floor is the most important step. If the flooring is a made of wood plank or boards, make sure these are even. Use a level over various parts of the present flooring to determine that the floor is even in all places. Uneven boards will break the smooth line of a tile floor allowing some tiles to rise above the others. Uneven tiles can be chipped on the corners, can crack with weather changes, and can shift causing cracks in the grout and in other floor tiles. If your flooring is uneven, changes will need to be made to the present porch flooring. If there is a wide variation in height over the current flooring, a professional might need to be brought in to replace a board or two. If there is a significant, but minor, difference, a subfloor is the answer. Subfloors can be added quite easily and will make the flooring base even for the tile.

The selection of subflooing needs careful consideration. Plywood or greenboard is the most commonly used subflooring. Greenboard is a product used by many professional installers to keep moisture away from the tiles and grout, but, if installed improperly, it can also create a moisture trap to destroy grout and tiles. Check underneath your present screened porch. If there is evidence of moisture or damage, then steps must be taken to minimize moisture from that source. Dirt mounds should be removed from underneath the porch. When that is finished, place a moisture or vapor barrier of extra heavy-weight plastic down to cover all the surface underneath the length and width of the screened porch. On top of the plastic, place gravel or small stones. If mold or damp boards are present, replace these to prevent future damage. In extremely moist climates, it is advisable to extend the plastic to an area surrounding the porch. A two to three foot flowerbed can be easily created with a plastic moisture or vapor barrier. Avoid selecting plants that need frequent watering or the purpose of the barrier will be lost. Commercially produced vapor barrier material can be purchased from home stores. If there is an extreme moisture problem, this product is highly recommended. Install the material on the underside of the porch flooring.

When installing subflooing for tile, some basic guidelines need to be followed. Stagger the seams so that it is difficult to see a pattern when the greenboard is complete. Where tile should form distinct patterns, greenboard should not form any pattern. Do not expect to see one long edge along the greenboarding. There is an important reason to avoid a long line underneath your tile. If a crack begins, it will be easy for the crack to continue along the ridge made by the edge of the foundation greenboard. If the greenboard edge is staggered, the grout crack will open only in a small section and not continue to grow as the greenboard expands or contracts.

It is important that drywall screws be used to put the greenboard or subflooring in place. While it may seem easier, and faster, to use a nail gun to install the subflooing, all of the hard work of tiling could be damaged in just one shift of the subflooring. Nails eventually work loose with traffic, especially on a porch. Screws placed every six to eight inches will ensure the subflooing or greenboard remains firmly in place. Put your subflooing or greenboard so it runs in the opposite direction of the porch wood flooring. By following this rule, the boards will not move with the porch flooring. This will also guarantee a stable flooring for the new tile.
If the present screen porch floor has a concrete base, make sure any cracks over a quarter of an inch in size are filled with a caulking that can expand with temperature changes. Break out any unstable concrete and fill the opening with the caulk. Let the caulking dry at least 72 hours before covering it with any subflooring. Avoid filling large cracks at one time. It is better to partially fill the crack and allow it to dry fully before layering in another amount of caulking. This may take three or four steps on particularly large cracks or openings. The time spent in preparation will mean a stable tile floor.

If a vinyl or plastic surface has been applied to the screen porch floor, this must be removed. Make sure any adhesive placed on the porch is also removed. This might seem like an unnecessary step, but with the weather exposure to a screen porch, there is potential for the adhesive to interact with the new surface board, damaging all of the hard work put into the new flooring.

Heavy plastic-based paint is sometimes used on porches. If the screen porch has a coat or numerous coats of this type of paint, the porch flooring should be well sanded before any other steps. Stain can also interfere with the ability of tile adhesive to do its job. If it is an oil-based stain, there are two options. One would be to remove the stain fully by sanding. The other would be easier, but more expensive. Placing greenboard over the top of the porch and nailing it in place would eliminate the need to sand the flooring. Tile adhesive will stick to stainded or painted board, but exterior weather conditions will make the new flooring last a shorter period of time.

An even, thick, sturdy, wood floored screen porch, without any moisture problem, can be tiled without using any subflooring. Rough sand the wood with sandpaper used for heavy duty jobs. This will allow more space for the tile adhesive. Do not sand to extreme, just enough to feel rough to the touch.

With just a few steps, a screened porch can be readied for a new tile floor. The impulse to avoid the work of removing an old floor or sanding the current flooring might be overwhelming, but the suggested steps will be well rewarded with years of pleasure from the new tile flooring.