Estimating Wall Layouts
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.
Tile Doctor Tip: A big advantage to mortar bed systems is that walls and curbs can be floated to allow the use of full tiles making the layout perfect.
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.