It is possible to shingle over a gambrel roof to add security from the elements or additional décor and aesthetic features to your structure. A gambrel roof is often thought of as a bard-style roof where the roof of a structure has multiple slope changes on either side of the roof. The application of shingles over a gambrel roof has very little variation from the application of shingles to a traditional roof. You should utilize three-tab asphalt shingles for this project.
Step 1 – Lay First Shingle
You will need to begin laying your shingles at an outer most corner of the lowest slope of the roof. Align the first shingle squarely with the roof and lay it into place. To secure the shingle, and all remaining shingles, you need to use the nail gun to insert three evenly spaced nails through the uppermost portion of the shingle. This will hold the shingle securely into place.
Step 2 – Complete First Row
Once the first shingle is in place, you simply need to work in a line laying the first row of shingles. Lay your second shingle directly next to the first, making sure they are even and properly aligned before nailing into place. Once the second shingle is in place, continue with the additional required shingles to complete the entire first row. When you reach the end of the row, you can trim the shingle if needed before nailing into place by scoring the tar side of the shingle with the utility knife and then snapping the unnecessary part of the shingle off.
Step 3 – Shingle Slope
You can now lay the second row. To begin the second row, start by placing a shingle directly above the last one in the first row. The shingles should overlap slightly, and the amount of overlap corresponds directly to the upper ridges on the previously laid shingle. Lay the entire second row in this manner, similarly to how you completed the first row. When you reach the third row, you should begin to alternate the placement of the shingles so that each shingle starts in the middle of the shingle below it. This will require you to precut and size the first shingle in the third row so it only covers the first half of the shingle below it. Then you can begin with full shingles for the remainder of the third row. Repeat these steps until you have shingled the first slope of the roof.
Step 4 – Slopes
When you reach a slope change, you will continue to shingle as you have been. The shingle may stand or sit up. This is okay, as over time the shingle will naturally fall into place and lay down.
Step 5 – Ridges
When you reach a ridge in the roof, this is the location you will utilize the caps. You simply lay the ridge cap over the last row of shingles, aligning it correctly over the ridge and nail into place.
It is best to shingle your roof on a warm day rather than a cool day because the heat and warmth will help keep the asphalt flexible and more manageable.