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How to Sheet the Gable Ends of a Garage

Mark Morris

Adding siding or OSB backing to gable ends can seem like a daunting task filled with complicated calculations and procedures that, if not done correctly, will end in disaster and the eventual collapse of the structure.

Lay out a full-scale template for gable end sheeting.

In reality the process can be done without too much in the way of calculation, or any dire consequences for you or your property. Determine whether your sheeting will be installed horizontally or vertically to accurately mark the sheets for an angular cut.

  1. Use a chalk line and string level to mark a line from the top of the garage wall, where it meets the angle of the gable on one side, to the same point on the other side. Drive a screw in at each point and tie a piece of mason's line tightly between the screws. Measure the distance along the line from one point to the other. Tie a piece of colored yarn in the exact middle of the string. Measure from the yarn to the underside of the peak on the gable.

  2. Snap a chalk line on the driveway in front of the garage and mark off the width of the garage from one bottom corner of the gable to the other. Clearly mark each corner. Use a drywall panel square to draw a line with chalk up from the center of this line to the height of the gable. Snap a chalk line between the top of the gable peak you drew with the square and each of the gable corners you marked.

  3. Measure up 4 feet for horizontal sheeting, or 8 feet for vertical sheeting, from the bottom line of this gable template and snap a parallel line across the width of the gable. Continue in 4 or 8 foot intervals, marking lines across the template to the top. Measure in from the left corner to 8 feet for horizontal sheeting, or 4 feet for vertical. Use the drywall square to mark vertical lines in 4 or 8 foot intervals across the template.

  4. Measure and cut one panel of sheeting to fit each 4-by-8 section in your template. To mark angles, simply mark the sides of the panel that intersect with the angled line at the vertical and horizontal dimensions of the intersection and draw lines between the marks. For instance: If the gable corner is at the bottom left of your first panel and it intersects that panel 48 inches in from the top right corner, mark the top edge of the panel at 48 inches and draw a line from the mark to the lower left corner. Use a circular saw to cut the panels. When cutting panels, be sure to compensate for any overlap, if working with plywood siding.

  5. Set up two ladders and have a helper lift and hold the pieces in place. Install the pieces, starting at the bottom and working across. Mark the location of stud centers along the top edge of each panel and use the drywall square to transfer the marks onto the face of the sheeting for easy location. Drive 2-inch, treated deck screws through the sheeting into each stud, every 10 to 12 inches. Trim pieces that fit too tight with the circular saw.