Concrete and Clay Tile Roof Covering Materials and Installation

Tile Roof Covering Description
Roof tiles are made using concrete or clay and come in several shapes. The most common shapes are flat and an S shape. Clay tiles are very delicate and are easily broken. Concrete tiles are more durable. Avoid walking on tile roof unless you are trained how to do so. Concrete and clay tiles are among the most expensive roof covering materials and usually have a long useful life.The underlayment material and the flashing are the waterproof membrane that seals the home from water penetration. The tile serves only to protect the underlayment from exposure to sunlight and excessive moisture and to look good. The provisions for tile application in this section are general and primarily for moderate climates. Refer to tile manufacturer’s installation instructions and local installation requirements for your area. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run.

Roof Slope Restriction
1. Do not install tiles on roofs with a slope less than (<) 2 ½ /12.
2. Install a double underlayment layer under tiles on roofs with a slope between 2 ½ /12 and 4/12.

Roof Deck Type Restriction
1. Install tile roof covering on solid sheathed roofs or on spaced structural sheathing.

Underlayment Specifications
1. Use at least (≥) 30 pound (per 100 square feet) roofing felt. This is the most common tile roof underlayment. Other materials, such as mineral surfaced roll roofing, are often superior to roofing felt. Refer to the IRC for other acceptable underlayment for tile roofs.
2. Refer to the IRC for additional requirements in wind speed areas of 120 mph or more.

Underlayment Application for Roof Slopes 4/12 and Greater
1. Begin at the eaves and apply at least (≥) a 36 inches wide strip of underlayment parallel to the eaves.
2. Lap horizontal joints at least (≥) 2 inches with the upper strip over the lower strip.
3. Lap end joints at least (≥) 6 inches.
4. Lap underlayment at least (≥) 1 inch over rake edges. (industry recommendation).
5. Use suffi cient fasteners to hold underlayment in place. The IRC does not specify fastener type and quantity.

Underlayment Application for Roof Slopes Between 2 ½ /12 and 4/12
1. Begin at the eaves and apply at least (≥) a 19 inches wide strip of underlayment parallel to the eaves.
2. Begin again at the eaves and apply at least (≥) a 36 inches wide strip of underlayment.
3. Lap each successive layer at least (≥) 19 inches over the previous layer with the upper layer over the lower layer.
4. Lap end joints at least (≥) 6 inches.
5. Lap underlayment at least (≥) 1 inch over rake edges. (industry recommendation).
6. Use suffi cient fasteners to hold underlayment in place. The IRC does not specify fastener type and quantity.
7. Refer to the illustration in Section R905.2.

Underlayment Application in 110+ mph Wind Areas
1. Apply underlayment according to the roof slope.
2. Install corrosion-resistant fasteners according to manufacturer’s instructions and space them along the overlaps at not more than (≤) 36 inches.

Batten Installation (Industry Recommendation)
1. You are not required to use batt ens when installing a tile roof, unless recommended by the manufacturer. If you use batt ens, follow these industry installation recommendations.
2. Install batt ens that are at least (≥) 1×2 utility grade wood, not longer than (≤) 4 feet, and installed with at least (≥) a ½ inch gap between each batt en for drainage. Alternative installations that allow drainage under or between batt ens are acceptable.
3. Space batt ens based on the size and type of tile and on the tile manufacturer’s recommendations.
4. Att ach batt ens using at least (≥) 8d corrosion-resistant nails spaced not more than (≤) 24 inches on center and long enough to penetrate at least (≥) ¾ inch into or through the sheathing. Alternative fasteners are corrosion-resistant staples at least (≥) 16 gage, 7/16 inch crown, 1 ½ inches long, and long enough to penetrate at least (≥) ¾ inch into the sheathing, and spaced not more than (≤) 12 inches on center.

Valley Flashing
1. Install at least (≥) a 22 inches wide strip of metal with at least (≥) 11 inches on each side of the valley. Use metal valley flashing with at least (≥) a 1 inch high splash diverter rib running down the valley center. The metal should be at least (≥) 0.019 inch thick galvanized steel or equivalent corrosion-resistant metal. Metal fl ashing sections should end lap at least (≥) 4 inches with the upper section over the lower section.                                                                                                                                                                                                          2. Install at least (≥) a 36 inches wide roll of ASTM D 2626 Type I roll roofing under the metal valley material, if the roof slope is at least (≥) 3/12.
3. Apply adhesive between the Type I roll roofing and the underlayment or install a self-adhering polymer modified bitumen sheet instead of the Type I roll roofing where the average daily January temperature is 25º F or less.

Sidewall and Penetration Flashing
1. Install roof penetration flashing, such as plumbing vent flashing, according to the flashing manufacturer’s instructions. Install roof and sidewall intersection flashing using base flashing and counter flashing installed according to manufacturer’s instructions.

Fastener Type
1. Install corrosion-resistant nails with at least (≥) an 11 gage shank and a 5/16 inch diameter head. The nails should be long enough to penetrate into the roof sheathing at least (≥) ¾ inch and completely through any sheathing that is less than (<) ¾ inch thick.

Perimeter Tile Nailing
1. The roof perimeter includes both sides of hips and ridges, gable rake edges, and eave edges.
2. Install at least (≥) one nail per tile within at least (≥) 3 tile courses of the perimeter and at least (≥) 36 inches from the perimeter edge, whichever is greater.

 

Field Tile Nailing in Standard Conditions
1. Field tiles are all tiles other than perimeter tiles and cap tiles on ridges and hips. Standard conditions are design wind speed of not more than (≤) 100 mph, and buildings with a roof 40 feet or less above the ground, and areas not subject to snow.
2. Install at least (≥) one nail per field tile when tiles cover solid roof sheathing and no battens are installed.
3. You are not required to install nails in field tiles when battens are installed and the roof slope is less than (<) 5/12.
4. Install at least (≥) one nail per tile when tiles weigh less than 9 pounds per square foot.
5. Install two nails per tile in areas subject to snow.

Field Tile Nailing in Special Conditions
1. You may be required to install nails in most or all tiles if the roof slope exceeds (>) 5/12, or if the design wind speed exceeds (>) 100 mph, or if the roof is higher than (>) 40 feet above the ground, or if the roof is subject to snow. Verify fastening requirements with the tile manufacturer and the local building official if any of these special conditions exist.

Tile Roof Covering Best Practice
Tile is usually a very heavy roof covering material. Verify that the rafters or trusses are designed and braced to carry the load. Do not install tile on a roof that was previously covered by another roof covering material without evaluation of the roof framing and support by a qualifi ed engineer or contractor. A good quality concrete tile roof can have a useful life exceeding 80 years. Thirty pound felt underlayment can start to deteriorate in as few as 10 years and may need replacement before the end of the tile’s useful life. Consider installing mineral-surfaced roll roofi ng as tile underlayment instead of thirty pound felt. Good quality underlayment and fl ashing materials should perform well for the entire life of the tile roof.