The large pipeflashing accessory can be used for cold pipes up to 18 inches in outside diameter or for hot pipes with a maximum of 14 inches in outside diameter. To install, line up the corrugations of the accessory with those of the Ondura sheet so the pipe to be flashed will come through the center of the accessory. Cut a 23" x 23" square hole in the Ondura sheet so the accessory will nest well. Apply two beads of butyl caulk around the square hole before placing the accessory.

Cold Pipes -- Install the same as the small pipeflashing accessory.

Hot Pipes -- Install the same as the small pipeflashing accessory.

Finishing Up -- Cut a full-sized Ondura sheet to a nine-corrugation width. Cut an opening 27 inches deep from the bottom edge of the sheet and five corrugations wide. Place the sheet over the flashing accessory so that it will cover the top and both side corrugations. This sheet should fit directly over the sheet to which the accessory is applied, be caulked to the accessory, and its upper end should be under the lap of the next higher row of Ondura sheets. Fasten with Ondura nails (see Fig. 26).

Chimney and Curb Mounted Skylights Flashing

The following is only a suggestion and is not intended to be a set of instructions. Each flashing situation will be slightly different. The goal is to let water run down the roof and around the chimney or skylight.

Cut the hole from corrugation valley to corrugation valley in the Ondura sheet surrounding the chimney or skylight. Remove all the material from the hole and the material up the slope, behind the chimney or skylight. If the chimney should fall at a corrugation crown instead of a valley, the flashing must be adjusted to fit.

The down slope or front flashing should be bent down into the corrugation valley (see Fig. 27) in line with both sides of the chimney or skylight. Use Ondura closure strips and caulk between the flashing and the Ondura sheet.

Make and install the left and right side flashings (see Fig. 27). These side flashings can be bent to the corrugation shape with a pipe or a wooden dowel. Caulk side flashing in the chimney or skylight to the front flashing, and to the Ondura sheet.

Make and install the back flashing. Use caulk to seal to all surfaces. Cut the width of the chimney or skylight from the lower end of another Ondura sheet so it will fit into place over the sheet around the chimney/skylight (see Fig. 29). Use closure strips and caulk between this sheet and the back flashing. Leave space between back of the chimney and the Ondura sheet so the water will not pond.

Valley Flashing

For valleys, install a minimum 24" wide metal valley flashing. Cut sheets or tiles at an angle to fit the valley; then turn over, and on the undersides along the valley edge, caulk two-corrugation pieces of closure strip in an overlapping pattern (Fig. 28). Then put a 1/2" bead of caulking on the flat side of the closure strips and on the sheet between the closure strips. Turn sheets or tiles right side up, carefully lay in place so caulked closures seat on flashing, and nail in place.

CAUTION: Never rely on closures to make joints capable of resisting substantial water pressure.