On new buildings, Ondura tiles install over solid decking of a minimum 1/2" thick exterior grade plywood (or thicker as required by your local building code). Cover this deck with a minimum 15 pound asphalt roofing felt (or heavier as required by your local building code). Install drip-edges and gable trim as desired or required. Seal the asphalt felt with roofing cement to all areas to be flashed. Now read "How To Make Sure Your Roof Is Square" to check the squareness of your roof.

CAUTION: Avoid installation when the material temperature is below 35°F.

Re-Roofing with Ondura Tiles

Ondura tiles make an ideal re-roof over both shingles (up to two old roof layers) and metal roofing.

Over shingles, simply nail in place as you would a new roof after first removing shingle ridge and hip covers and repairing any rotted or unstable deck.

Over flat, standing seam metal over a solid deck, simply flatten the metal seams and proceed as if over shingles. Check local codes for other dry-in procedures.

Over corrugated or irregular metal roofing, we recommend use of Ondura sheets instead of tiles.

Drive Shingle Nails and Ondura Nails Correctly

Drive shingle nails through the valleys 4 1/2" from the top edge of the tile so that the lapping tile covers heads. Drive perpendicular into roof decking - not at an angle - so nail head is snugly in contact with tile. See Fig. 14. Don't overdrive or underdrive nails. You can also use a roofing nail gun: however, never use a staple gun.

Use only genuine 3" Ondura nails to drive through corrugation crowns at the eave, through ridge cap at corrugation crowns, and at the lower corners and center of end lap of each tile to protect against wind lift. See Fig. 16.

Repairing Holes

Repair nail-size holes by either filling with flexible butyl caulking; or coating the shank of a screw with butyl caulking and screwing it into the hole.

Planning for Ventilation

All roofing requires ventilation. It's a false economy to try to conserve heat in an uninsulated building by closing off ventilation openings. That's because poor ventilation can cause severe condensation problems and dripping, which in turn can cause deterioration of roof framing and covering materials.

See Fig. 36, for suggestions on how to take advantage of Ondura's corrugated design and Ridgeline Ridge Vents and Ondura Ventilated Closure Strips to assist ventilation.

NOTE: The flexibility of Ondura sheets and tiles may lead to misalignment or "spreading" if care is not taken to keep sheet and tiles at nominal width (48") during installation.