When I see a home with a tile roof, my first thought is, “Nice roof”. A roof goes from “nice” to “Wow, that roof is spectacular!” when the installer pays attention to the details. Some details that make a difference are appropriate flashings, or chimney, skylight and wall metal work that is consistent and does not detract from the aesthetic look of the roof. However, nothing conveys the knowledge and skill of a craftsman more than crisp, clean, straight lines of tile, row after row.Consistent row spacing (exposure) is aesthetically more appealing. It requires dividing the space between the top and bottom of the roof by the number of rows while avoiding a short course at the ridge. Using long division and 1/8- inch increments from a tape measure is one way to achieve this goal. However, that’s a method that challenges my calculator, let alone eager installers who just want to start pounding nails. They may believe it’s easier to deal with the ridge when they get there! It’s no wonder new installers can be intimidated by the layout stage of a tile roof installation. Even experienced installers may miss opportunities to minimize cuts, increase efficiency and achieve that “perfect look” we all admire.
WHAT IS LAYOUT?
Unless precluded by a specific manufacturer’s design, proper clay and concrete tile installation requires a 3-inch minimum overlap. That means a typical 17-inch-long concrete tile has a “maximum exposure” of 14 inches. If the goal is to space the rows evenly, we must first determine the location of the eave course and ridge course. For example, if we find the space between the eave and ridge courses is 140 inches, we can have 10 rows set at the maximum exposure of 14 inches. Perfect!
But what if the distance is only 135 inches? Setting nine rows at 14 inches will require us to cut 5 inches off of our top row. Cutting the tile would remove the fastener holes and tile lugs and make the top course uniquely short, taking away from a precision aesthetic. Most tiles have an “adjustable headlap”, meaning the overlap can be increased. If we set each of the 10 rows at 13 1/2 inches, we would absorb the extra 5 inches evenly over the entire slope with an extra 1/2-inch overlap per row. Row spacing would be consistent; fastener holes and lugs intact; and we would not have to cut tile, drill new holes and throw away the scraps.
The math is not always as easy as an extra 5 inches divided by 10 rows. Eighths and sixteenths don’t work well in long division. The TRI/WSRCA Concrete and Clay Roof Tile Installation Manual, from the Edmonds, Wash.-based Tile Roofing Institute and Morgan Hill, Calif.-based Western States Roofing Contractors Association has a Quick Reference Chart on page 27. It shows proper row spacing for sample eave- to ridge-row measurements. You may find situations where the chart is helpful.
HORIZONTAL LAYOUT USING THE SWING TAPE METHOD
Craftsmen develop “tricks of the trade” that make complicated tasks simple, their work easier or the finished product better. The “Swing Tape Method” does all three.
To avoid the math and use the Swing Tape Method, installers mark their measuring tape at the maximum exposure of tile they are using. Continuing with the example of a 17-inch tile and a 14-inch maximum exposure, the tape will be marked at 14, 28, 42, 56 inches, etc. Using the 135-inch eave- to ridge-course distance in the previous scenario, the installer would place the tip of the tape at the eave-row chalk line and run upslope to find the top-row chalk line at 135 inches. Seeing his tape is marked at 140 inches, the installer would swing his tape in an arc to the left or right until the 140-inch mark aligns with the top-row chalk line. Although the tape is marked in 14-inch increments, the now diagonal lay of the tape has shortened the distance of each horizontal row to 13 1/2 inches. The Swing Tape Method arrived at the same conclusion as the previous arithmetic. The installer marks the underlayment with chalk or a crayon next to each 14-inch increment on the tape measure. He repeats the same process at the other end of the slope and then chalks horizontal lines along the new markings on the underlayment.
Using a tape measure with this method requires marking each row onto the underlayment. This only should be done with chalk or a crayon. Scarring the underlayment with a nail or screwdriver can lead to premature failure of the underlayment.
A modern advancement to the Swing Tape Method uses Layout Tape instead of a marked tape measure. Layout Tape is a paper roll marked with red arrows highlighting the maximum exposure for the tile being used. In this example, the arrows would be at 14-inch intervals. Using the same process as with a marked tape measure, the installer can secure the Layout Tape, placing a red arrow on the top of the eave-row chalk line, then unroll the tape upslope to the top-row chalk line. Using the same 135-inch eave- to ridge-course example, the installer will find a red arrow 5 inches above the top-row chalk line. He will swing the tape to the left or right until the red arrow lines up with the top-row chalk line. The red arrows become the targets for the horizontal chalk lines. Because the Layout Tape is left in place, the installer avoids the step of marking each and every row on the underlayment.
Of course not all roof slopes are simple rectangles. Some roof designs are quite complicated and as installers we have to play the hand we are dealt. The Swing Tape Method can help you make the best of challenging situations by allowing you to virtually try out different layout options. If a slope has multiple ridgelines, you can set the tape to the most beneficial location. This may reduce your cutwork or put a short course in the least visible location. On larger sections, you may choose to adjust the row spacing to better accommodate ridgelines, headwalls or dormers. Be aware that midslope adjustment of exposure can result in a change to the diagonal line of the tile sidelaps but does not affect function.
Using the Swing Tape Method with Layout Tape or a marked tape measure appropriate for the tile being used will ensure proper exposure. It will also reduce cutting and increase your efficiency while laying the foundation for a picture- perfect installation.
SWING TAPE METHOD STEPS
1 Determine eave-course placement (consider eave closure, gutter, desired overhang) and snap a line to place head of the tile or top of the battens if battens are to be used.
2 Determine top-row placement (consider ridge riser board, ventilation, etc.) and snap a line to place head of the tile or top of the battens if battens are to be used.
3 Using Layout Tape or a marked tape measure, place an arrow or mark at the eave-course line. Measure straight to the ridgeline. Swing the tape to the left or right until an arrow or mark aligns with the top-row chalk line.
4 If you are using Layout Tape, fasten the tape. If you are using a marked tape measure, you must mark the underlayment at each mark on the tape measure.
5 Repeat this process at the other end of the roof. Snap lines between the arrows or marks on the underlayment.