Tile Installation: >> Estimating/Layout
Welcome to estimating and layout. This is the section that holds important keys to a successful, visually appealing, and cost-effective project. The type of tile and method of installation has already been chosen or at least under serious consideration. The layout is one of the last things to do prior to actually setting the tile.
When we need to estimate the amount of tile needed to complete a project, we must first determine what tile we are talking about.
FIELD TILE: Field tiles are those tiles that are flat and form the field or largest part of a tiled installation. Field tile is generally packaged in boxes indicating their total combined square foot coverage. This means that we need to convert our measurement into total square feet that is required to complete the installation. This method is simple and easy to follow. The drawing made at the time the project was considered is necessary now. If no drawing was made then, it should be now. Simply divide the area of installation into manageable sections. Take the width, in inches, and multiply it by the length, in inches. This gives the total square inches. Next divide that number by 144. This gives you the square feet. Take all the sections and add the square feet together resulting in the total square feet required for the project. It is a good idea to add 10% to that number for waste of difficulty. More than 10% is required for some types of fragile tiles or those known to be prone to breakage within prepackaged cartons. Be sure to ask your reputable tile dealer for his recommendation in this area.
TRIM: Trim is generally divided into two categories. These are conventional or radius and surface. Conventional or radius trim is that which is applied to a surface above the plane of the adjoining wall surface. Surface trim is applied to a surface on plane with adjoining wall surfaces.
Trim is generally packaged and sold by the piece or linear feet. The outbound edge of the installation when measured in running inches will determine the required amount of trim. Then pick the trim size and convert the measurements to suit your needs. Like field tile add 10% to the amount at least. It is very common to make mistakes when cutting trim pieces.
Dr's tip: When cutting trim, measure twice, cut once. Always err on the cautious side. It is better to cut trim pieces a little too long than a little too short. We can always visit the saw again.
DECORATIVE ACCENTS: Decorative accents are simply calculated by determining how many you want and where. If you have a great deal of field tile accents, it might be a good idea to subtract the amount from your field tile needs. In the case of liners, which generally follow trim lines, simply calculate their number as you would trim pieces.
PATTERNS IN TILE: Many tiles today have various patterns to choose from. The patterns are established by variances in the tile size or shape. Most tile Manufacturers and dealers have the various patterns that their tile will suit and at least pictures of those patterns. The square foot calculations for patterned floors become a little more complicated as the number of tiles in a square foot varies with the pattern. Your reputable dealer will convert your square foot requirements for you.
ADHESIVES/GROUTS: Manufacturers of these products will have average coverage values posted on the containers of their products. Rarely have I seen these values grossly inaccurate.
MORTAR ESTIMATING: Mortar, whether pre-mixed or on the job mixed, is given in cubic foot measurements. To convert that to square feet works like this. Consider that your mortar bed averages one inch thick. For every twelve square feet of surface, you have accumulated one cubic foot of mortar. Use this formula as an estimate only. It is better to have a little too much mortar on hand than not enough.
The areas that are in question are the other required materials. Again, this is an area where your notes and drawing are very helpful. Once you choose a method, you can set about the task of estimating your materials. How much lumber, screws, nails, staples, and other materials must be considered.
For a good layout certain tools are necessary. The first on the list are measuring tools. They include tape measures, squares, chalk lines, pencils, straight edges, levels, and if you wish a story pole.
Keep reading and examining the drawings and photographs for the use of these tools. Also peruse the diagrams that describe how to check levels, squares, and straight edges for accuracy.
The only item on this list that probably needs explaining is the story pole. The tile worker makes a story pole with a straight edge made of metal, wood, or plastic. A sufficient number of tiles are placed on the ground against the straight edge and is arranged with the desired grout joint size. The story pole can then be placed against a wall or floor and an estimate can be made whether cuts will have to be made. I have never used one. I prefer to use measurements of the tile placed on the floor in a straight line for my measurements.
A note on the mortar bed advantage. Mortar beds can be placed at various minimum and maximum thicknesses. This allows the installer to adjust surfaces to accommodate surfaces that are slightly out of plumb, square, and level. This also allows the installer to adjust the final setting bed to accommodate full or half tile. We will see later that full tile is always preferred and tiny cuts avoided.
What is next? A proper layout is essential for several reasons. In the introduction I mentioned visually appealing and cost effectiveness. A proper layout will look good and the viewers eyes will move across the installation without stopping and causing the viewer to think, "why was that done?" Tiny cuts are a dead giveaway to a poor layout and are not visually appealing.
I mentioned cost effectiveness. The fewer cuts, in most cases, results in less wasted time and tile. Every tile that is cut, unless in half, is a full tile used. Also, every cut requires a trip to the saw or cutting board. Hence, only cut when you have to. Let's look at layouts in their actual specific use.
FLOORS: The first layout consideration in floors is based on vision. Where will the eye first fall? Sometimes this is at the point of entry into the room. If the room has multiple entrances, the eye may naturally travel to the longest wall. I would say that in the case of a bathroom, the eye would first go to the base of the shower or tub. Each room must be considered individually. Sometimes in layout there are many choices that will work. We need to pick the one we feel will "look" the best. Where do we start?
In the case of tiling one room, take measurements in both directions. Compare these measurements to the tile and joint size chosen. This will indicate whether full tiles or cuts are necessary. If you end up with tiny cuts at one wall, it will be more visually appealing if you shift the field so that larger fuller tile is used even if you have to cut at both ends.
It is also necessary at this time to include in your measurements if any trim pieces are to be used. In the case of cove tile and the like, room for the tile must be added to your measurements and allowances made.
In my experience, the best approach is to identify the longest wall and establish the first "working line." Working lines are lines on the floor made with pencil, marker, or chalk line. These lines can and will possibly be moved several times during layout. If you are using chalk lines, do not spray the lines with clear lacquer until all of the lines are made.
Dr's tips: When you identify your longest wall, make your first working line far enough from the wall for at least one trowel. This allows you to use the line and still apply a bond coat between the first tile set and the wall.
To establish the line, measure out from the longest wall at two places and make reference marks. If the room is large, over 6-8 feet, use a chalk line. If not, you can use a straight edge and pencil.
Dr's tip: When using a chalk line, be sure that you carefully align the chalk line with the reference marks and pull the line as tight as possible prior to snapping it. Also, place the chalk line as close as possible to the reference marks, while aligning it, without actually touching the surface. When the surface is touched, chalk will be left. Additionally, always retract the line into the tool for each line snapped. The chalk line is of no value without chalk.
Now you have your first working line properly spaced from the longest wall allowing room for a trowel pass between the line and wall. This first line is placed after you have established where the field of tile will start. We now need to check the room for square. This is accomplished by making a perpendicular line on an opposing wall at the exact spot the tile needs to be placed. Use the reference marks again to establish the line. Now you have a choice. A Large roofing square can be compared to the intersecting lines and an estimate of square can be made. A better method is the mathematical approach called the "3-4-5" method.
The 3-4-5 method is derived from geometry, which calculates the dimensions of a triangle. In practice, a measurement is made down the longest wall line from the intersection of the two lines. A reference mark is made at 4 feet. Next measure down the other line and make a reference mark at 3 feet. Now measure the distance between the two reference marks. If the measurement is 5 feet, the walls are square. If they are not an adjustment will need to be made.
Dr's tip: This is an important measurement. "If you start out square, you will end square."
Now it's decision time. Will spacers be used or will the installation be "grid set?" There are advantages to both. Let's talk about spacers first.
Spacers can be used if the tile is nearly perfect in square and size when compared to each other. I can illustrate this thought by saying that if the room is large there will be many tiles involved. Lets say there are 30 6"x6" tiles in the length of the room and 20 6"x6" tiles in the width. Spacers are used and the tiles are not quite the same size. Let's say they vary 1/32" each. All that needs to be done is multiply 1/32" 30 times and you get the picture. Those nice straight lines you started out with now looks like a snake.
Spacers will work very well if the tiles are uniform and the room is relatively small. If spacers are used, only the original lines are necessary when the installation is started. After the installation is started, it is mandatory to occasionally check square by measurements using a straight edge or chalk line while the installation is in progress.
Dr's tip: Spacers must be removed after the job is completed and cured prior to grouting. In my opinion, it does not matter whether the spacers are thin or not. There will not be sufficient grout depth at tile intersections if spacers are left in.
This leads us to the grid set method. This method is preferred if the installations are large, multi-room, the tiles are irregular, or if special patterns are involved. The advantages to this method far outweigh the additional time involved in laying it out.
It works like this. From the original lines established, grids are chalk lined onto the setting surface. The grids are marked on the entire surface in both directions from the original lines. This step forms boxes that the tile will be set in. What size are the boxes? This will depend on the tile size and the installer's ability. The box must be large enough to accommodate the application of the bond coat by notched trowel while not too large to make setting difficult. The lines also must be established with perimeters that include the tile and grout joints. Look at the diagram and photographs of this method in use.
This method is also preferred as it allows the installer to view the entire installation and cuts prior to one tile being set. Also, with this method, an installer can start anywhere in the project and the grout joints will line up. It is especially desired if there are any structures within the field of tile like that of islands or special designs.
Let me illustrate this dialog by a suggestion. Let's say that the tile chosen is 12"x12" and the grout joint chosen is 3/8 inch. I would pick a grid or box measuring 12 3/4"x12 3/4". This leaves a grout joint between the two tiles and at two ends. The tile would be set within the box or grid always orienting the tiles in the same two sides of the box wherever on the floor they are placed. For example, look at the floor and decide where you will orient the tiles within the grids. Then always repeat this orientation in each box within the installation.
One other method exists in layout and this method utilizes a "metal tile rack." This tool is made of steel rod, which is as thick as the desired grout joint width. After the setting bed is placed, the rack is laid down and the tiles are placed in the rack and beaten in. The rack is then removed leaving the tiles in place. Grids and working lines need only to be established for the rack and not the tile. This method is particularly useful when the installation method is a fresh mortar bed and pure cement bond coat. This method is not seen very often. However, it is still used.
WALLS: Walls are different than floors for one important reason. This is the mandatory use of some type of trim. Since tiles generally do not have a finished edge, it is necessary to apply some sort of trim tile. As we have already read, tile trim is available in many shapes and sizes. The important thing here is that room for that trim be planned on and figured into the layout. Generally, wherever the field tile ends, there will need to be trim pieces installed.
Looking at the examples, it is apparent that wall layouts depend on visual appeal. This means that it is sometimes necessary to cut at both ends to "balance out" the layout. This is especially important in tub and shower enclosures. It was quite common to see the tile installer of the past simply start at one end of a tub back wall and set tile to the other end. This is still acceptable especially if the cut end is half a tile or larger. However, is that what you want? This method can be problematic and not recommended if there are any special patterns or "in field" trims present.
So where do we start? If the installation is to be over an existing surface, we first need to check the surface for plumb and square if necessary. Square would only be necessary if tile is to be installed below the tiled wall in the case of a shower floor or tiled "roman" tub. This could also be necessary in the case of countertop installations.
If the surface is plumb, it is time to decide whether to start in the middle or from one end. While it is perfectly acceptable to set chalk lines in this process, I prefer to use simple straight edge or level and pencil lines. This is especially true for small wall installations like shower or tub enclosures.
For tub and shower enclosures, start at the back wall and establish a centered vertical line using a trusted spirit level. Why trusted? If your level is not accurate, your line will not be plumb. This will throw the entire layout out of whack. This initial line should extend from the base of the installation to the top or where the tile will end. Next is the horizontal line.
The horizontal line is established in a different way. It is preferred to have full tiles at the point where the lower tiles meet the opposing surface. This may be the top of the tub, shower pan, or floor. Also, use full tiles where the counter splash meets the countertop. In many cases, it is possible to start the first course of tile on top of the opposing surface. The opposing surface may be a tub or shower pan, floor, or countertop deck. If the preference of the installer is to use a ledger to support the tile while the bond coat cures, read on.
Measurements will need to be established to indicate where the horizontal lines need to be placed. A good idea is to establish the line allowing sufficient room for one trowel pass for the bottom row of tiles. This allows the installer to accurately apply the bond coat to the substrate to a uniform depth. This measurement must allow room for the tiles, grout joint, and 1/8" for sealant at the joint below. Look in the expansion joint section for more details on this recommended procedure.
Now we have a measurement for the horizontal line. Make a reference mark where the measurement is needed. Then using the spirit level horizontally, make a line from one end of the wall to the other. Be sure to check that horizontal line against the vertical line using a trusted steel square. In the case of tub and shower enclosures, continue that line onto both sidewalls using the level again. Now you have a vertical line and horizontal lines. If the installation is not in an enclosure, it should be treated as any other tile surface layout.
If the installation is an enclosure and uses conventional trim, the preference is to start the tile where the trim ends on the front edge of the sidewalls. This means that the only lines used are the center back wall line and the horizontal back and sidewall lines. In the case of enclosures, the working lines are complete at that time.
If the installation calls for surface trim when the enclosure side walls are in plane with the rest of the room, it will be necessary to erect vertical working lines at the front of the enclosures side walls. These lines can be established to allow full tile from the front edge to back wall, if desired. A spirit level is used again and checked with a trusted steel square.
COUNTERTOPS: Layouts for countertops are a combination of all of the above. It is essential that the countertop layout be visually appealing. Full tiles should abut trim at the front of the deck. Full tiles should be at the bottom of the splash. Generally it is more visually appealing to have the trim and field centered on the sink. This is not always possible. It is necessary to carefully examine the top to determine the best layout. The layout will be dependent on the size of tile, joint width, and chosen trim/accents.