The feeling is unmistakable. Your body tells you that you are on a stiff trampoline but your eyes tell you that you are not. The wood floor you are walking across is bouncing. Has this ever happened to you? It has happened to me when I walk across the floor systems of many a new home. The floor joist systems are built to code, however they have considerable bounce to them. If you have ever lived in an older home, the feeling is quite unsettling.

Springy Floors Hurt Tile

Wood floor systems with a bounce are fine if you decide to carpet. Sheet vinyl products can also tolerate substantial movement. Hardwood flooring will also fair well on a somewhat bouncy floor. Ceramic tile, on the other hand, will suffer drastically if a wood floor system is too bouncy. Tiles will crack, grout will crumble, and floor tile will sometimes actually detach. The reason is simple. Ceramic flooring materials are rigid. As such, they require a rigid base to stay in one piece. Wood floor systems can meet the necessary rigidity requirements. However, certain guidelines must be followed.

I Beams - Height is Everything

Steel I beams have certain strength or load bearing characteristics. Wood floor joists are no different. Their strength is a function of the thickness of the joist, its height, the type of wood and the distance between supports. Many people realize some of these factors, however, not everybody recognizes that all of them come into play. The species of wood is very important. For example, a 2x10 floor joist made from southern yellow pine is significantly stronger than a similar sized joist made from spruce-pine-fir.

Subflooring is Critical

The flooring material installed on top of the floor joists is also important. If you are using plywood, this material also can flex. Thicker plywood is almost always more rigid than thinner plywood. The number of plys or layers in the sheet is also important. Many people do not realize that plywood of the same thickness can have a different number of plys. More plys is almost always stronger.

Tile floors need additional support other than a thick single piece of plywood. Three quarter inch tongue and groove plywood, believe it or not, will not suffice! An additional layer of 1/2 inch plywood or 1/2 inch cement board is usually required.

As for installing this extra material, you just don't lay it down and bang it in with a bunch of nails. It is vitally important that the seams of both materials are staggered from that of the plywood subfloor. This offset should be a minimum of two inches. Edges of the materials are most secure when screwed.

If you use cement board as an underlayment, it is necessary to spread wet thinset on the plywood subfloor! This thinset will fill any void spots that may exist between the two layers. These void spots often are caused by floor joists that are crowned differently.

Existing Floors

What do you do if you have an existing floor that is bouncy? This is a tough call. There is no miracle fix, I can assure you of that. Adding additional beams under the floor in the basement or crawl space is the easiest. This solution immediately stiffens the floor because you significantly decrease the span of the joists. If it is possible to do this, always make it your first choice.

Another solution is much more extensive and not always successful. You can install a "stress skin" on the underside of the troubled floor joists. A stress skin is a layer of plywood that is glued and screwed to the bottom of the floor joists while they are temporarily jacked up. The plywood, once the glue is dried, acts to stiffen the floor joists.

This solution must be engineered. In other words, you must hire a structural engineer to develop a plan as to how to install the 'skin'. Remember, this solution is not always worth the effort.

Wood floor joist systems will work with ceramic tile. I have used ceramic and slate extensively in my own new home. I only have one cracked floor tile in my entire house. This tile crack, I feel, occurred as a result of lumber shrinkage.

Read my "Floor Joists Materials-Span Table" article for the allowable span limits for your wood floors by two to three feet and you will be blessed with stiff wood floors. Or, use as tall a joist as you can afford.

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Common Floor Joists Materials - Span Table

These tables state that the given floor joists will not deflect more than 1/360th of the span as long as they are spaced no greater than 16 inches on center and the load will not exceed 40 pounds per square foot (PSF) live loading plus 10 PSF dead load. Span is defined as the greatest distance along the bottom of the joist between supporting beams or columns. If there is any doubt in your mind, contact a structural engineer.

If you are planning a house or a room addition, be sure to consult with a structural engineer. Have him or her specify the actual floor joist size. In addition, ask the engineer to verify that the wood joist delivered to the jobsite is, in fact, the correct material. Look on the side of the joist for the grade and species stamp!

Common Floor Joists Materials-Span Table

Ceramic Tile Floor Installation Tips

Layout - The Key to Good Looking Work

Layout of a tile job is the key to a pro looking job. You need to be sure that you don't end up with tiny pieces at a threshold or along a wall. These always look bad. Rooms are sometimes not square. This means that if you start with a full tile along a wall, you may end up cutting tile or adding slivers of tile.

Chalk a center line each direction in the room. The lines, at the center where they intersect, must be square! Do a 3-4-5 triangle to verify for square. From the center where the two lines cross, measure three feet down one line. Then measure four feet down the other line. Using your tape measure, connect the two dots at the ends of these two lines. If you get exactly five feet the two center lines are square!

Now, take some tiles from a box and begin to lay them out with the proper spacing between them until you get to a wall(s). See what you end up with. Hopefully it will be approximately half a tile. Do the same where the tile will meet another floor. If you can start with a full tile at this location it sometimes looks much better. Remember, this other floor must be square to the tile layout! Adjust your lines until you are satisfied with your layout.

Glue - Thinset - Mastic

The adhesive that you choose depends on several things. If you use a plywood subfloor, an organic or epoxy adhesive is recommended. If you are setting your tile on cementitious board or concrete, a cement based thinset works well. The thickness of the adhesive is a function of the type of tile you are using. Tiles often have different bottom surfaces. Some are smooth, some have lines and some have lugs. If you put on too little adhesive, void spaces will be present under the tile. This can cause tiles to crack under concentrated loads. Too much adhesive will cause the grout lines to fill up with adhesive. This is a mess! The tile manufacturer will always tell you how much adhesive and which type trowel to use.

Cutting Tiles

There are several ways to cut tiles. Many glazed tiles can be scored with a tile cutter and snapped successfully. However, it is tough to do this along an edge if you are trying to just take off 1/2 inch. You can also use a diamond wet or dry saw. The wet saws, with a good blade, make smooth cuts. You can also buy a rod saw made from carborundum that fits in a standard hacksaw. This works fine but is slow going. Finally, a nipper tool will "bite" off chunks of tile for weird cuts.

Grouting

Grouting is difficult. You must work in small areas not allowing the grout you just applied to get too hard. When striking the joints use a grout sponge with rounded edges. Squeeze as much water as possible from the sponge. Too much water weakens the grout! It will crack and powder. Often you may have to rinse the sponge five or six times just to do a one foot by two foot area! Practice in a closet if you have never done this before. A poor grout job will show!

Cementitious Board Manufacturers

Cement board is readily available. Just about any ceramic tile supplier stocks this commodity. It is often 1/2 inch thick and comes in pieces three feet wide by either four, five or six feet long. Be sure to get a set of installation instructions from your supplier! Don't listen to him/her if they say to just put it down with galvanized roofing nails. There is more to it than that!

There are just a few companies that make cement backerboard for ceramic tile installations. Basically, all of the products are the same. The board comes in different sizes and often two thicknesses. One half inch thick material is used for wall tile installations. One quarter inch thickness is often used for countertops. The cement board is held together by a layer of fiberglass mesh on each outer surface. USG Corporation's product has small Styrofoam balls in it to reduce weight. Their product also has two sides to it. The rougher side is for thinset applications. The smooth side is for organic mastics.

You can find these cement boards in home centers and ceramic tile outlet stores. Be sure to obtain written installation instructions for the product you choose. They all differ slightly from one another.

• Georgia Pacific Corp.
  Their product is called ToughRock®. 
• United States Gypsum Company USG
  Their product is called Durock. 
• Fin Pan, Inc.
  Their product is called Util-A-Crete.
• American Gypsum 
• CertainTeed

• James Hardie Building Products
  Their product is called HardieBacker™ Cement Board.

• Custom Building Products
  WonderBoard® Cement Backerboard
  RhinoBoard® Fiber Cement Backerboard
  EasyBoard® Ultra Light Backerboard

07/08

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Installation of Ceramic Tile Backer Boards

Keep it Away From the Ledge!

The biggest mistake, that is commonly made when installing any of the tile backer boards, is allowing them to come into contact with the flat ledge of the tub or shower pan. This is a HUGE mistake. In the event the caulk seal between the bottom row of tile and the tub/shower fails, water can get behind the tile. If the backer board is touching this ledge, it will readily soak up this water like a sponge. In fact, because of capillary attraction, the water can actually begin to climb UP the backer board. Given enough water, the situation can become critical. The backer board becomes soaked, it transfers this moisture to the wood framing members, and BINGO, wood rot begins. It can be a serious problem.

The best thing to do is to hold all tile backer boards up 1/4 inch from these ledges. Then, before installing the tile, apply a bead of pure silicone caulk between the backer board and the ledge.Tool the joint with your finger so that no caulk projects beyond the front plane of the backer board. Any excess caulk may interfere with the installation of the ceramic tile. It is also a good idea to caulk all seams where the backer board touches another piece of backer board. This means all inside corners and any other horizontal seams as well.

Manufacturer's Instructions

Virtually every manufacturer of tile backer boards has specific installation instructions. These instructions cover nailing patterns and joint taping. These instructions vary depending upon the product you intend to use. Be sure to obtain and follow these instructions.

Vapor Barriers

When installing any of these products, it is a good idea to install a four or six mil plastic vapor barrier on the wood framing members before installing the tile backer boards. This vapor barrier should actually be installed before the tub or shower pan is installed. It should extend from floor to ceiling. This barrier only takes a few minutes to install and will prevent damage to your home. The Tile Council of America requires this vapor barrier in almost all installations. They have an excellent publication outlining ceramic tile installation procedures. It's called Handbook for Ceramic Tile Installation. It is a wonderful publication that will help you obtain the best possible results on your next tile job.

Manufacturers of Ceramic Tile Backer Boards

• American Gypsum
• James Hardie Building Products
• National Gypsum Company
• USG - United States Gypsum Corporation
• Georgia Pacific Company
• W.R. Bonsal Company
• Custom Building Products

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Backer Boards

Water is a very unusual compound. Several days ago, I spoke to a large group of gardeners. I indicated that water is necessary for the survival of their plants, so in that sense it is their friend. However, water used in abundant amounts too close to their houses can be their worst enemy.

The same is true for those of us who are not avid gardeners. Water is needed in our everyday lives. However, it can cause massive damage to our houses if not respected and controlled. Thus, those areas of our homes where water use is concentrated must be somewhat waterproof.

Bathrooms & Water

The average bathroom in a residential house has the highest concentration of water usage. It stands to reason that this area of the house needs the most protection from both water in the liquid form and water in the vapor state.

Shower and bathtub areas are of the highest concern, as it is here that water can most easily escape from the tub or shower area. Showering activity is really the biggest problem, especially if the shower area is constructed of ceramic tile. Think of it, we direct a concentrated stream of water against a wall surface that isn't integrally connected to the actual plumbing fixture (the tub).

The plumbing fixtures in a bathroom are always waterproof. They don't easily or readily deteriorate when exposed to water. Take toilets for example. Water sits in these fixtures from the day they are installed until the day they are removed without harm. Tubs are not harmed by water.

However, wall surfaces abutting plumbing fixtures can be seriously damaged by water which originates from the plumbing fixtures.

Waterproof Walls

Many people like the beauty and design possibilities which are possible when using ceramic tile. Ceramic tile is unaffected by water. In fact, standard ceramic tile is no different than the toilets we just spoke of above. Ceramic tiles and toilets are manufactured using refined clays which are glazed and hardened by a firing process in a high temperature kiln. The glaze turns into a thin coating of glass over the clay, making the tile impervious to water.

During the past several hundred years, homeowners and builders found out that concrete was not harmed by continuous exposure to water. It didn't take too long for them to figure out that you could apply a thin layer of concrete to a wall surface. Ceramic tile could be easily applied to this concrete surface by using a cement paste. In fact, if the ceramic tile was set into the fresh concrete surface within a day, the two became one in most instances. Prolonged exposure to water would not separate the two materials.

Modern Alternatives

The old method of attaching ceramic tile is still available. However it is very labor intensive. This added labor boosts the overall installation price beyond the capabilities of the average homeowner. Manufacturers of wall system products quickly responded to fill this gap.

Today there are three wall system products that you can use as a substrate for ceramic tile installations. All three are faster to install than the old fashioned concrete. However, there is a wide difference in overall performance of the three products. Fortunately, it is still possible to achieve the results of the old tile setters with several of the products.

Moisture Resistant Gypsum

Some gypsum wall product manufacturers make a gypsum board which is used by many builders and remodelers. It is marketed as moisture resistant drywall. The problem is that many people confuse "moisture resistant" with "waterproof." They are not the same. Not by a long shot.

Moisture resistant simply means that for some period of time the gypsum will resist the effects of moisture. After that period of time, deterioration will begin. My experience with these moisture resistant gypsum products is that they begin to fail within three to five years. Failure can occur at an earlier date if exposure to water is severe.

The process of deterioration begins with the paper which encases the treated gypsum core. The paper, even though it has been chemically treated to resist moisture, actually begins to dissolve or degrade when exposed to constant moisture. This deterioration exposes the chemically treated gypsum core to moisture. Eventually the gypsum core softens and your ceramic tile begins to fall from the wall.

The Next Step Up

Manufacturers were quick to realize that the moisture resistant gypsum couldn't do the job. So several of them developed products which exhibited higher performance characteristics. In fact, one product was based solely on the already known concrete system which had worked for years.

One day, somebody just thought "Why reinvent the wheel?" Why not manufacture concrete in manageable, easy to use sheets which can be nailed to walls? BINGO! Cementitious board was invented. This product has been around for approximately 15 years and has worked extremely well. It offers long-term durability with somewhat easy installation. What's more, with modern thinset cement adhesives, you can actually install ceramic tile on these boards that will not fall off when exposed to water!

Cementitious boards, however, are somewhat tough to install. You cannot nail close to the edge of a board without it fracturing. Also, cutting the board and producing a smooth edge is nearly impossible. Cutting holes is done either with a hole saw which produces dust, or by using a chisel, which makes a jagged cut. These disadvantages are minor, however, when you consider the fact that the products will not be affected by water.

The third alternative with respect to ceramic tile backer boards is a material which takes the qualities of moisture resistant drywall and cementitious board and blends them together. It is important to realize that this backer board is marketed as a water resistant material, not waterproof. It has a gypsum core made with a proprietary silicone treated chemical process. This board also substitutes fiberglass matting for the chemically treated paper found in the previously mentioned gypsum backer boards. The final component to this backerboard is a heat-cured, co-polymer water and vapor-retardant coating on the finished side of the board.

This new product is backed by a 20 year limited warranty. It can be easily cut with a standard razor knife and it installs just like standard gypsum products.

Water Vapor, Hmmmmmm

The fact that only one of the products has the ability to inhibit water vapor is quite interesting.The cementitious boards cannot make these claims. Water vapor can and does penetrate these products. Water vapor can also penetrate the moisture resistant gypsum.

Water vapor can be a significant problem if a shower or tub wall is also on an exterior wall, especially in colder climates. During cold weather, if a vapor barrier is not present on the warm side of a wall system, water vapor can pass through insulation and subsequently condense on the cold side of the wall. This condensation leads to serious water damage in short order.

The Bottom Line

If you want your ceramic tile job to last and you want peace of mind, what should you install? If you want ease of installation, choose the silicone treated gypsum product. If you want to be assured of long term durability, select a cementitious board installed with a plastic vapor barrier. Remember, the cement system has already proven that it can withstand the test of time. This we know for sure.

The key to success in using either material lies in proper installation. The materials must not be allowed to come into contact with water. This is especially true of moisture resistant gypsum board and the cementitious boards. Both of these materials can soak up water like a sponge. This water will destroy the gypsum in short order as we have discussed. It will not harm the cementitious board, however, it could begin to rot out the wood framing members to which the board is attached.

Just remember, do everything possible to keep water in its place, that is, in the plumbing fixtures!

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Caulking and Sealing Tile Grout Tips

When installing new ceramic tile, absolutely make sure that the horizontal seam between the bottom row of tile and the tub and/or shower is not grouted! This seam must be caulked with the best quality 100 percent silicone caulk you can buy. These caulks are available in various colors, should you be using a colored grout. Grout will shrink after installation and a very tiny crack will exist, trust me.

The best way to caulk this crack, believe it or not, is to do it in your bathing or birthday suit. Why, might you ask? The reason is simple. The tub should be filled up to the overflow with water when caulking this joint. The added weight of 30 to 50 gallons of water plus your body weight can cause the floor below the tub to deflect. Leave the water in the tub as long as possible to allow the caulk to cure. Don't leave water in the tub like this, however, if you have small children at home! Left unattended, they may think the tub is a swimming pool. Drownings have been known to occur.

AUTHOR UPDATE - April 2015: The following material not in red color was written before I had extensive experience with homeowners who had SEALED their grout and then had the grout get stained by a liquid that had seeped UNDER the sealant. That can happen along the line where the grout touches the tile.

In these cases, the homeowners discovered it's nearly impossible to remove the stain because all cleaners are REPELLED by the sealer.

Now I suggest to people to NOT SEAL grout. If you use Stain Solver, a Certified organic oxygen bleach, it will remove any stain from grout in minutes. 

After the grout is dry (three to five days), seal the grout with a silicone grout sealer. These products are available at your tile supplier. Be careful not to get these products on the tub or shower floor, as they are very slippery. The grout needs to be sealed, as it can and will absorb water. Remember, grout is nothing more than fine cement. The sealers also help to keep the tile grout clean. Reseal the grout every six months, after thoroughly cleaning the grout.

Existing Construction

Do all of the above, however, clean, clean, clean before caulking or sealing. These caulking and sealing products will not stick to soap scum very well!

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