Knowing how to build a gable roof over a deck will not only save you money, it will also enhance the beauty of your home. Make your deck a luxurious living space protected from the weather. Although this project may seem like a real challenge, with the right tools, materials and some basic building skills, it can be accomplished in 2 or 3 weekends.
Step 1: Measure Post Locations
Mark corresponding areas and cut out spacing to install the foundations for the support posts. In the ground below the deck, dig holes approximately 18 inches deep by 18 inches wide. These will house the concrete molds that will support each post location.
Step 2: Anchor Posts
Place the molds for the concrete forms into the holes for the supporting posts. Mix the ready-mix concrete and carefully fill the forms. Be sure to place each of the support post anchors on top of the molds, setting them firmly in place before the concrete dries completely. Be sure to allow at least 24 hours for the ready-mix concrete to dry thoroughly and to firmly set the post anchors.
Step 3: Install Supporting Posts
With a tape measure, carefully measure the roof dimensions and the needed sizes for each of the supporting posts. Mark the posts and carefully cut them to size, checking that each end is cut squarely. Place the 4x4 support posts in the post anchors and loosely attach them with 10 x 5/8 inch bolts, washers, and nuts. Use a plumb-bob to ensure the posts are plumb. Tighten the nuts and bolts to temporarily hold the 4x4 support in place.
Step 4: Attach Framing for Trusses
Measure, cut and attach two of the 2x8 pieces of framing lumber between the centers of the supporting posts on each side. Either nail or clamp these pieces temporarily to each side of the 4x4 supporting posts. Using the 10-inch lag bolts, secure each of these 2x8 pieces to the supporting 4x4 posts making sure they are squared to the top, and level with the supports. Tighten these lag bolts and the ones at the bottom of each of the 4x4 supports.
Step 5: Mark and Attach Trusses
Beginning at the shorter side of the deck roof, mark the locations for the roof trusses every 24 inches on the center of the tops of the 2x8 pieces of lumber. Carefully place trusses precisely on the marks made and nail them into place, one at a time.
Step 6: Attach Roofing Materials
To provide for roof decking, nail the sheeting pieces of ¾-inch plywood to the trusses. Attach roofing felt to the plywood with roofing tacks. Be sure to overlap the roofing felt 4 inches at all edges. Next, install the roofing drip edge and finish with roofing shingles. Paint your gable roof as required.