Corrugated Asphalt Roofing by Onduline North America
ONDURA® Shed Roof Project
Is it time to repair or replace the roof on your backyard shed?
Please consider ONDURA corrugated asphalt roofing sheets for that roofing project. ONDURA corrugated asphalt roofing sheets are the easy-to-install DIY roofing material for a shed roof, and are available in several colors.
- Utility knife
- Measure tape or yardstick
- Pencil or marker
- Protective eyewear
A typical 10-ft by 10-ft shed with a gable roof can be covered by 6 ONDURA corrugated asphalt roofing sheets, three sheets on each side. Lets go through the calculations.
Most sheds have a roof slope ratio of 4:12 to 6:12 (e.g., 4-inch rise for each 12 inches of run).
For this example, the slope ratio is 5:12, which is 22.6 degrees. At this angle, the gable roof for a 10-ft by 10-ft shed will have a rake edge of 65 inches. Now add 2 inches for the roof sheathing (i.e., plywood or OSB) overhang at the eave (Note: Your overhang may be different), and another 1 inch for the ONDURA overhang beyond the edge of the sheathing. That gives us a rake edge length of 68 inches.
Eave Edge of Roof: 10 feet (120 inches)
Rake Edge of Roof: 5.7 feet (68 inches)
Each ONDURA corrugated asphalt sheet is 48 inches wide and 79 inches long. The corrugations run along the 79-inch length of the sheet, so we have to align the sheets so that the rain will drain off the roof. That means the 48-inch wide side is aligned with the eave edge of the roof, and the 79-inch long side is aligned with the rake edge of the roof.
When installing more than one sheet, we have to account for the one-corrugation overlap from sheet to sheet. The width of the one corrugation overlap is 4 inches. Therefore, the first sheet gives us 48 inches of coverage, and each additional sheet gives us 44 inches of coverage.
TIP: Since each corrugation is 4-inches wide, you may find it helpful to think in terms of how many corrugations you will need to cover the roof.
A 10-ft wide roof (10-ft along the eave edge) is 120 inches wide. Each corrugation on an ONDURA corrugated asphalt sheet is 4 inches, so we will need 30 corrugations to cover the width of the roof.
Each ONDURA corrugated asphalt sheet has 12 corrugations. Three sheets side by side with one corrugation overlap at each of the two seams will give us 34 corrugations:
(3 sheets x 12 corrugations) – 2 overlaps = 34 corrugations
This means we will have 4 extra corrugations. The easiest solution is to trim the 4 corrugations from the center sheet, and this also looks good when the sheets are installed.
Three ONDURA sheets will cover one side of the roof. To cover both sides, we need six sheets of ONDURA.
NOTE: The 79-inch length will accommodate sheds up to 12-ft wide on the rake-edge side with a gable roof at a slope up to 5:12. If the shed or structure is wider than 12 feet on the rake-edge side, a second row of ONDURA sheets will be needed to extend the coverage up to the ridge of the roof.
- Number of fasteners needed per sheet: 17 min./24 max. for 3 rows of fasteners, with rows spaced approximately 24 inches apart
- Number of fasteners for roof ridge: 6 fasteners per foot of ridge (3 on each side)
- Fasten sheets on every corrugation at rake edge, eaves, and overlaps. For other fastener rows you may fasten on every corrugation or on every other corrugation. Fastening on every corrugation provides better wind resistance.
- Fasten ridge caps at every corrugation.
For the 10-ft by 10-ft shed, the length of the rake edge is 68 inches (including overhang at eave). The maximum spacing for rows of fasteners is 24 inches between each row. Therefore, we will need four rows of fasteners (See nail-placement diagram below):
- Ridge Cap row of fasteners (on every corrugation): 30 fasteners
- Intermediate row of fasteners: 17 fasteners
- Intermediate row of fasteners: 17 fasteners
- Eave row of fasteners (on every corrugation): 30 fasteners
Total number of fasteners for each side of the roof is 94 fasteners. Therefore, we need 188 fasteners to install ONDURA on both sides of the roof.
- Ridge cap sections should overlap by at least 7 inches.
The ridge of the roof is 10-ft long (120 inches). ONDURA Ridge Caps are available in two lengths: 79 inches and 39 inches.
To close the ends of the ONDURA Ridge Caps, we will need 4 inches of ONDURA Ridge Cap overhanging each end of the roof ridge (See installation instructions for more details). Therefore, the total length needed is 128 inches.
If we are installing the 79-inch ONDURA Ridge Caps, we will need two 79-inch ONDURA Ridge Caps.
If we are installing the 39-inch ONDURA Ridge Caps, we will need four 39-inch ONDURA Ridge Caps.
- 44 inches long
- 4 strips per pack
- Should be used at roof ridge and eaves.
The ridge of the roof is 10-ft long, and both eaves of the roof are 10-ft long. We will need to install the closure strips under the ONDURA sheets on the eave edge of the roof, and between the ONDURA sheets and the ONDURA Ridge Cap along each side of the roof ridge (See closure strip diagram below). For the two eaves and the two sides of the ridge, we will need four rows of closure strips, and each row will be 120 inches long. Since each closure strip is 44 inches long, we will need 3 closure strips for each row. A pack of ONDURA closure strips contains 4 closure strips, so we will need 3 packs for the roof of the 10-ft by 10-ft shed.
Here is the list of materials for installing ONDURA sheets on a 10-ft by 10-ft shed with a gable roof at a slope of 5:12
- ONDURA Sheets (12 corrugations/sheet): 6 sheets
- ONDURA Nails: 2 boxes (100 nails/box)
- ONDURA Vented Closure Strips: 3 packs (4 strips/pack)
- ONDURA Ridge Caps (Long: 12.5 inches by 79 inches): 2
We provide additional information on the following pages on this website:
- General guidance for calculating materials for a project: Calculating Materials page.
- Installation instruction videos: Videos page.
- Installation instruction documents: Installation Instructions page.
ONDURA corrugated asphalt roofing sheets are available at Lowe's stores and other home improvement stores.