Clay and Concrete Tile Installation

Clay and concrete roof tiles are heavy, rigid units laid in overlapping courses. They are installed in two broad ways: batten-hung, where nibs on the back of each tile hook over horizontal timber battens, and direct-to-deck, where tiles are fastened to solid sheathing over underlayment. Batten-hung roofs are standard in the UK, Europe, Australia and much of Asia; both methods are used in North America.

Battens and counter-battens

Battens set the gauge (spacing) of the courses and provide the fixing point. Counter-battens, running up the slope under the battens, raise them off the underlay so water and air can drain. Canadian guidance for one tile system specifies 25 x 100 mm (1 x 4 in) spruce battens, spaced in equal divisions of no more than 345 mm (13 3/4 in) from eave to ridge.

Fixing methods

• Mechanical fixing. Nails, screws, wire ties or clips secure tiles to battens or deck.
• Mortar setting. Traditional bedding of ridge, hip and verge tiles in sand and cement mortar, and in some regions of field tiles.
• Adhesive setting. In some hurricane-prone markets, approved foam adhesives are used to set tiles to the underlayment in place of or in addition to fasteners.
• Clips. Tail clips or storm clips hold the lower edge of each tile against uplift.

Fixing frequency depends on wind exposure and pitch. Canadian guidance for one system fastens every fourth row on slopes up to 5:12, every other row from 5:12 to 12:12 and every tile above 12:12, and calls for storm clips on buildings over 12.2 m (40 ft) high or where wind speeds exceed 130 km/h (80 mph).

UK practice

In the UK, BS 5534 requires single-lap tiles and ridge and hip tiles to be mechanically fixed, and says mortar can no longer be relied on as the only fixing. Perimeter tiles are fixed twice, and fixings are calculated from site wind loads.

Ridges and edges

Ridges and hips are finished with ridge tiles set on mortar or a dry-fix system. Verges can be mortar-pointed, finished with cloaked verge tiles or fitted with dry verge units. Eave closures or bird-stops fill the gap under the first course of profiled tiles.