If you are adding an addition to your house or replacing a pre-existing roof, you will most likely be building the structure of your new roof with wood. Besides shingles, insulation and waterproofing, the average home's roof is entirely wooden. Thus, the most important component of a roof is the wooden trussing, frame and fiberboard panelling. All of these components can be easily assembled with timber and just a handful of tools.
Measure and cut 2 by 6 lumber to the length necessary for your roof. For information on what the exact length of a diagonal truss should be for a given roof size, consult your state's building codes.
Plug two 2 by 6 pieces of timber into a galvanised steel connector plate. Secure the connection by drilling 3-inch deck screws through the holes in the plate and into the wood. Use this truss as a model for the others. Trusses should be spaced out every 2 feet and aligned lengthwise across the roof. Given that the average house is 2,000 square feet, with a roof width ranging from 40 to 50 feet, you will most likely need between 20 and 25 trusses. Change your planned number accordingly based on the width in feet of your roof.
Attach a 2 by 4 brace to each of the trusses, plugging it into the connector plate and securing it with deck screws.
Cut a 2 by 6 piece of timber. To determine its size, multiply the number of trusses used in your project by the 2 feet of space typically left between them. Add an extra 2 feet to the timber's length to allow for 1 foot of overhang on each side of the roof. This length of timber will serve as a frame for your trusses.
Secure the trusses to the frame. Space them 2 feet apart and secure them to the connector plate with deck screws.
Add fiberboard panels to the roof. The panels should be at least 4 by 6 feet in length and secured to each truss with at least two bolts each. Make sure that the entirety of the roof is covered in fiberboard.