How to Install Clay Roof Tile

Roof tile pattern, close up

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Clay roof tiles are very popular as they create an attractive mediterranean look. They're durable and lightweight, making them ideal for certain roofs, and they offer better insulation when compared to similar materials such as ceramic tiles. When installing clay tiles, picking the right size, color and installation method, which depends on the type of clay tile, are important factors.

The Right Slope

Clay tiles work well on roofs with slopes greater than 20 degrees. As the slope increases, it enhances the aesthetics of the tile, making it ideal for cathedral-type roofs. Before starting, make sure that the surface is level; if it's not, apply mortar or a thin-set product to level the surface.

The Right Roofing Underlay

One of the most important considerations for installing clay tile is to have a great roofing underlay. The material used below the clay tile is a critical factor that will affect the tile's durability. Normally, the underlay is made from asphalt-saturated roofing material covering all area below the tile clay cover. Ensure that it's properly attached or installed or you can end up with overlying tiles pretty quickly. Install an extra layer near the roof edge and in valleys to protect the surface even more. As a minimum, cover all decks with two layers of No. 30 asphalt-impregnated roofing felt or one layer of No. 43 coated base sheet.

Choosing the Right Clay Tile

Choose clay tiles based on the climate of your geographic area as they are manufactured to withstand different environmental conditions. The most common type of clay tiles include:

  • Slate: Thin rectangular sections of rock that come in varying sizes and thicknesses.
  • Plain Tiles: Small rectangular sections of clay with a smooth or sanded surface finish.
  • Pantiles: A distinctive clay tile with an "S" shaped profile.
  • Roman Tiles: Similar to pantiles but with a cross-section that is flat with a small role.

How to Install Clay Tiles

After installing the underlay, it's time to install the metal flashing around chimneys, conduits, vents and where the roof meets a vertical wall. A 28 gauge corrosion-resistant flashing is recommended. Follow these simple steps to install your clay tiles:

  1. Position the first tile on the batten with the crown facing up and center the tile from side to side. Drive a 10d nail at the base of the clay tile into the batten. Don't overdrive the nail. Verify that the tile overhangs the end of the batten by two inches.
  2. Add some mortar underneath the first clay tile to provide additional support. 
  3. Install another tile atop the inner end of the first. Measure from the outer end and adjust the end of the second tile.
  4. Nail the second tile to the batten in the same way you installed the first one.
  5. Place two tiles to the opposite end of the ridge and install them as you did with the previous one.
  6. Measure the distance across the ridge from the outer ends of the first tiles at each end of the ridge. Subtract 16 inches and divide the result by 8 to determine the number of tiles to install.
  7. Start at the second tile at one end of the ridge. Install the tiles toward the center of the ridge from end to end and install half the number of ridge tiles. Work from the opposite end and install the remaining tiles to the center of the ridge. A key tile installs at the center of the ridge with mortar.

Type of Mortar

Use a medium consistency mortar so it's manageable and easy to apply. Install the mortar at the outer end of the first ridge tile, packing it under the outer edge of the tile to fill the gap at the tile and batten. Smooth it with the trowel. Continue adding mortar along the lower edges of the ridge tiles at each side. Install mortar at the outer end of the tile at the opposite end of the ridge and apply enough where the ridge tiles meet at the center point of the ridge. Place a key ridge tile at the center of the ridge and remove the excess mortar with the trowel.