What Kind of Decking Should Be Installed for a Clay Tile Roof?

Continuous Decking

• The National Roofing Contractors Association suggests continuous roof decking under a clay tile roof. Tongue and groove boards form the continuous decking. This decking system utilizes lumber with grooves cut in one edge and tongue, shaped to fit within the groove, on the other. When you interlock the tongues into the grooves, the roof decking becomes more solid and has a greater weight-carrying capacity.

Plywood Decking

• Plywood decking is an option and would likely save money in both material and labor costs over tongue and groove decking. Use plywood of at least 5/8-inch thickness as decking under a clay tile roof system. The plywood should also be exterior grade. Do not use Oriented Strand Board because of possible problems with nails pulling through the material.

Underlayment

• No matter which decking you choose, a felt underlayment is required. Felt roofing paper, more commonly called tar paper, protects the roof during the construction process and also serves as a final protection for the home if the roof tiles leak. Type II roofing paper is heavier than Type I and should provide a longer usable life. Two layers of roofing felt are recommended on roofs with a slope of less than 10 inches of vertical change in 12 inches of horizontal distance.

Ice Dam Protection

• Ice dams occur when snow on the roof melts but freezes as it approaches the eaves of the house. The barrier of ice holds water on the roof, which may then leak into the home. In areas where this may occur an extra waterproof membrane can help. Place it over the felt underlayment for an area from the edge of the eave to a point at least two feet further up the roof than the point of the wall under the roof.