How to Build a Cross-Gabled Roof

A gable roof is the simplest roof to frame. A cross gable is just two gable roofs set
perpendicular to each other, providing more interesting house shapes. This roof design handles heavy rains with a minimum of fuss.

Things You'll Need

• Blueprints
• Ladders and scaffolding
• Dumpster
• Tarps and plastic sheeting to cover plants and AC unit
• Lumber
• Woodworking tools
• Work boots, gloves, hard hat, knee pads, tool belt
• Underlayment material
• Shingles or other finishing material
• Hardware, including nails, screws and metal ties

Instructions

Create the Plan

1. Contact a builder or architect to help with the design. He lays out the floor plan and estimates the slopes of the eaves.

2. Review the original drawings with a structural engineer. She can take measurements, factor in weather considerations and then come up with the final design and blueprints. Check with your local code office for building code requirements. Pull all permits and arrange for inspection dates.

3. Scout your area for contractors. Interview several and base your choice on work ethic, previous experience and compatibility, as well as price. Keep in mind that shingling requires specialty laborers. Provide tools, if possible.

4. Select the materials based on your budget and how long you estimate the roof should last. Climate and extreme weather eliminates certain materials from that area.

5. Calculate your roof area from the blueprints. Add 10 percent for waste. Divide by 100 to get the number of square feet. Round up and use this number to figure out costs and material needs. Purchase and arrange for delivery of all materials. Have lumber and sheathing delivered directly to the roof.

6. Check your insurance policy for liability coverage, and check with your state for worker's compensation requirements. If you hire day laborers or specialists, you may need to withhold and file payroll taxes.

Construct the Roof

1. Cut the ridge boards and mark rafter placement to match up with wall stud layout. Cut rafters for a gable or cross-gable roof all to the same length. The birdsmouth is located in the same place on all rafters. Before framing the roof, lay several panels of plywood across the ceiling joists to provide a platform for the workers.

2. Bring all the roof plywood up and stack on the ceiling joists. Pass up the ridge boards and orient to the length of the gables. Bring up the rafters next and lay them with the plumb cuts facing the ridge board.

3. Work on the main gable first. Nail two rafters on one side of the ridge beam at either end of the board. Raise the ridge up until the birdsmouths are flat on the top plate of the wall. Nail these rafters to the walls. Nail two rafters on the opposing side ends, forming an A shape. Tack these to the top plate.

4. Install a stud in the gable end from the ridge to the top plate. Use a level to plumb it. Nail a 2- by 4-inch brace near the top of the stud. Nail a block to the plywood walkway, catching a couple of ceiling joists underneath.

5. Put the level on the 1 1/2-inch side of the stud and plumb it. Nail the 2- by 4-inch brace to the block to center the roof in place. Lay the remaining rafters in place, alternating from side to side.

6. Establish the ridge board for the cross gable. The inside rafters should be flush against the original gable. Nail the far end rafters into place and correct the center. Install the remaining common rafters. Nail on the collar ties and fascia. The valley between the gables needs flashing to protect against the weather. Nail plywood sheathing to the common rafters.

7. Finish the roof by framing in the gable ends. Lay the undercoating and then lay the shingles. Start on the side that's least visible from the street. This gives you time to gain experience.

Tips & Warnings

• If you're doing the work yourself, maintain your balance at all times. To aid in this, keep the roof free of debris and work from the ridge down. Set a steady pace and don't overexert yourself.

• On steep roofs, work with a ladder jack that holds one or two scaffold planks.

• Dump debris directly into a container, if possible. Secure the dump area from pedestrians.

• Never work in the rain or lightning storms.

• Keep away from the power line into your house, and keep an eye on power tool cords and air hoses.