The design of a house's roof is just as important as the design of its facade Beyond its aesthetic appeal, a roof also needs to be able to resist wind and other natural forces. Along with showing the exact shape of the intended roof, roofing plans also list the intended building materials, placement of vents, and what lies directly underneath (underlayment). Roof plans are often drawn to a smaller scale than the house's floor plans (1/8-inch=1 foot or 1/16-inch=1 foot). Have a drafter look over the final plans to troubleshoot any potential design problems.
Draw a replica of your floor plans onto a piece of graph paper. Use the floor-plan blueprints as a reference and make sure to draw your own plans to scale. The equal-sized squares on the graph paper will make this task easier. Be as accurate as possible when drawing your plans.
Calculate the pitch and slope of your roof. Local building codes may have specific guidelines that you have to follow when designing your roof. The pitch of the roof is determined by the rise and run of the roof. The run and rise are measured in equal units, so a roof that has a run of 12 units and a rise of 4 units will have a 4/12 pitch (approximately 18-degrees). Pay attention to how the different sections of the roof intersect and the angles those intersections create.
Decide on the shape of your roof. The roof doesn't have to be a single style, but can incorporate several different ones. Some of the most common shapes are A-frame, flat, gable, shed and hip. Before deciding on a particular roof shape, ensure that the shape can be built to the intended pitch of your roof.
Select your building materials. The pitch, building style, cost and climate are all deciding factors in choosing materials for your roof. Shingles are the most commonly used building materials and come in a variety of styles. Tiles and metal panels are other options for roofing material. Roofing materials appear on the roof plan as a list that also includes the weight and underlayment.
Contact a drafter to look over your plans. The drafter can help you with the more technical aspects of your roofing plan, including the placement of vents and the size of the attic space. Since drafters are trained in roof planning and construction, they'll be able to locate any possible trouble spots on the plan and remedy them before construction begins.
Always follow all local building codes when designing your roof.