How to Add Asphalt Shingles to a Gambrel Roof
Covering your gambrel roof with asphalt shingles is more expensive than using foam or rolled roofing, but often provides better protection against leaks and lasts longer. A gambrel roof has many individual sections with different slopes. Shingling this type of roof is slightly more complex than shingling a flat or biplanar roof. However, laying the shingles on the slope is not hard if you work on a hot sunny day.
Step 1 - Measure Roof and Purchase Materials
Roofing materials are sold by the square. One square of shingles is enough to cover 100 square feet. Measure the surface area of the roof you are going to shingle. Make sure to account for all the different angled sides as well as any gables you’ll be shingling across.
Step 2 - Work on a Clear Hot Day
Choose a day with fair weather to work on your roof. Avoid days with a high chance of rain. Compared to other types of roofing jobs, it is especially important to choose a very hot day to shingle a gambrel roof. You will utilize the warmth of the sun to loosen up the tar strips on the back of the shingles and bend them to the roof surface. If you choose a day that is too cool the shingles may not flex. It is not advisable to warm them with a heat gun or blow dryer because the heat is too concentrated and may damage the shingles. If this is not feasible, use roofing cement to help stick shingles at slope transitions. You can also install flashing at the transitions to anchor the first row of shingles on the new slope.
Step 3 - Remove Old Roofing Material
Use a crowbar to start prying up the old roof surface. Continue scraping it off with a shovel. Remove old fasteners such as staples, screws, and nails as you go so that you will have a flat surface to work from. Once the old roofing material is removed you have a chance to inspect and repair the roof sheathing and frame.
Step 4 - Install Tar Paper and Shingles
Stretch sheets of tar paper across the roof surfaces and staple them into place. Trim them to fit with the utility knife where necessary. Use the level and chalk line to help run the sheets straight.
Step 5 - Nail in Shingles
Start at the outer corner of the lowest point on the gambrel roof. Lay the first shingle and nail it into place. Nail the second shingle adjacent to the first. Continue setting a row to the edge, trim the last piece to fit with a utility knife. For subsequent rows, overlap shingles according to the manufacturer’s specifications. The shingles have notches or tabs on the top half that you will line up to measure overlap. When the roof slope changes, just let the tabs point straight up. Let the bottom tabs cover the lower sloped section and nail along the tar line on the back of the shingle into the higher sloped section. Bend square shingles as ridge caps along the roof peak.