See fig. 4 in Getting Started 2

1. From the comer where the eave and rake meet, measure along the eave 48 inches and mark.
   
2. From the corner of the rake and the ridge, measure along the ridge 48 inches, plus or minus the out-of-square distance determined earlier, and mark.
   
3. Snap a chalk line between these marks for sheet alignment.
   
4. To establish a drip-edge overhang of all eave sheets, drive nails into the corner rafters at either end of the eave, and stretch a line between them 1 3/4" out along the length of the eave. Visually align each sheet of the eave row with this string for a uniform drip-edge.
   
5. Now you can install the first sheet. Starting at the rake edge of the sheet, nail down the first corrugation at every purlin so that this edge is aligned with the rake.
   
6. Now flex the sheet so its opposite edge aligns with the chalk line. Nail along the crown of the second corrugation from this edge, then nail the remainder of the sheet (see Fig. 12 and 13). If using closure strips, install before nailing eave.

1. From the corner where the eave and rake meet, measure along the eave 48 inches and mark.
   
2. From the corner of the rake and the ridge, measure along the ridge 48 inches and mark.
   
3. Snap a chalk line between these marks for sheet alignment.
   
4. To establish a drip-edge overhang of all eave sheets, drive nails into the corner rafters at either end of the eave, and stretch a line between them 1 3/4" out along the length of the eave. Visually align each sheet of the eave row with this string for a uniform drip-edge.
   
5. Starting at the eave/rake corner, fasten the rake corrugation of the first sheet of Ondura at each purlin up the rake (see Fig. 8 nailing pattern).
   
6. Now align the opposite edge of the sheet with the chalk line. Nail in place (see Fig. 8) along the second corrugation from the chalk line to allow for the side lap of the next sheet. In using closure strips, install before nailing eave.

You can now install the remainder of the first row.

1. From the first chalk line, mark off successive 44-inch spaces along the eave. Do the same at the ridge. (The 44-inch distance allows for a 1-corrugation side lap.)
   
2. Snap chalk lines between the eave and ridge marks for sheet alignment.
   
3. Noting the nailing pattern in Figure 8, install the rest of the eave row (see sidelap in Fig. 19).
   

The second row can be installed so that all side-laps meet lower sheets in the middle, or so that all side-laps line up from row to row up the slope of the roof to offset the sidelap of one row from the other.

Remember: The flexibility of Ondura sheets may lead to "spreading". This can be helpful if you need to "stretch" the width of the sheet or it can cause problems if done inadequately by pressing down on the sheets as you install.

NOTE: For instruction on installing the ridge and other installation tips, go to Finishing.