On new buildings, Ondura sheets install either over purlins (as illustrated in these instructions) or over solid decking covered by roofing felt. Over decking, simply follow these same instructions making sure decking is secure before nailing down sheets. We strongly recommend solid decking for buildings with interior ceilings.

(For instructions on installing Ondura Tiles, go to Tile installation)

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

Re-roofing with Ondura Sheets

Ondura works well as a new roof over an old asphalt shingle roof. Over roofs with a generally uniform surface, just install sheets using nails long enough to penetrate 1" into supports of decking beneath. Over corrugated metal or other irregular roofs, first install nailer strips using lumber spaced appropriately for the slope of the roof, then lay Ondura sheets per instructions. Be sure nailing strips are securely in place. You may need to use 4" Ondura nails depending on the thickness of your base material.

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.

Drive Nails Correctly

CAUTION: Use only genuine Ondura nails for installing sheets and tiles (tiles at eave and ridge only). See Fig. 5. Other types of nails may not provide sufficient hold-down strength.

Pulling Nails from Sheets

To pull a nail from a sheet, use a claw hammer and a 1 1/2" wood dowel or pipe. (This technique minimizes the chance of damaging the sheet). Put the dowel or pipe in the valley next to the crown with the nail to be pulled. Then use the dowel or pipe as a leverage point for pulling the nail. See Fig. 7.

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.

For larger holes, carefully pull nails from damaged corrugations, then cut a full-length sheet so it's wide enough to cover the hole, plus two corrugations. Lap one corrugation on each side of the hole, and slip the upper end of this sheet under the lap of the row above. Nail in place.

Walking on Ondura Sheets

Installation of roofing materials can be dangerous. The relative amount of danger is increased by the height from the ground, increasing pitches of the roof slope, inclement weather conditions or other factors. We strongly recommend anyone installing Ondura or working on a roof in any manner take all precautions possible to insure their personal safety.

When walking on nailed-down Ondura sheets, walk on top of purlins only, placing feet across corrugations. Also, wear soft-sole shoes.

Ondura is more pliable in hot weather; less pliable in cold weather. Always use care in walking on Ondura or any other roof.

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 excessive heat buildup in the summer and severe condensation problems and dripping in the winter, 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.

CAUTION: Improper or inadequate ventilation will void warranty.