How to Sheath a Gable Roof

Calculate the amount of sheathing you will need for the roof, so you can purchase all the supplies you need before starting. The sides of a gable roof are rectangular, so to find the area, you'll need to measure the height and width of one side of the roof. Multiply the height by the width to find the area of that side, then multiply that number by two to find the square footage of the entire roof. Finally, multiply the square footage of the roof by .15, then add the product to the square footage of the roof. This final calculation gives you the total square footage, plus 15 percent to accommodate wasted material as the result of mistakes. This is how much sheathing you should buy.

Snap a chalk line over the tails of the rafters on each side of the roof. Measure the tails of the rafters. Saw off the ends of any tails that stick out farther than the other tails, so that the tails form an even line.

Lay a panel of sheathing on the lower left hand corner of one side of the roof. Sheathing comes in panels of 4 feet by 8 feet. Lay the panel so that it is wider than it is tall. Line up the left edge of the panel so that it is flush with the gable, and the bottom edge so that it is flush with the eave of the house. The rafters will be spaced so that the right edge of the panel will fall directly over the center of a rafter, but if this is not the case, use a circular saw to cut the panel so that the right edge is centered over a rafter.

Nail the sheathing to each rafter with a nail gun and roofing nails. The nails should run in vertical lines up the panels, spaced every 6 inches on outside edges and every 12 inches in the middle.

Lay the next panel of sheathing to the right of the first panel, so the left edge of the panel abuts the right edge of the previous panel. The right edge of the new panel will be centered over the rafter beneath it. Nail the sheathing to the rafter in the same way that you nailed down the first panel, with nails spaced 12 inches apart in the middle and 6 inches apart on the sides. Continue in this way to nail down the sheathing until you've finished the first course. You may need to cut the final panel of the sheathing with a circular saw to fit the space if a full-sized panel does not fit.

Cut the first panel of the second course of sheathing in half so that it is a 4-by-4 foot panel, then nail the panel to the rafters in the same way that you nailed the first panel of the first course into place. The bottom of this panel should abut the top of the panel beneath it. After the first panel in the second course, use 4-by-8 foot panels all the way across the second course, so the panels are staggered with the panels in the first course.

Nail the first panel of the third course into place without cutting it, then install the rest of the course in the same way that you installed the first two courses. As you start each new course, alternate between using 4-by-4 foot panels and 4-by-8 foot panels as the first panel in the course. You may need to cut the panels in the final course length-wise to fit in the space left.

Repeat this process on the other side of the roof.