Excerpt: If the addition is not too complicated, drawing the plans is a real option. Several sharp pencils, sheets of vellum (for converting into blueprints) and some rudimentary drafting tools are all you need. If you've never done it before, the learning curve is a little steep and you'll make some mistakes, but the building inspectors will make sure you comply with the code and zoning requirements. What they won't do is make sure you get the floor plan and door and window placements you want. So take care and be sensitive to what you want and need from the new space.
Excerpt: The toughest part of the addition to draw -- and, for that matter, to build -- is the roof framing and how it ties into the existing roof. Even a simple gable roof can be a challenge for the novice.
Excerpt: To help you along we suggest you invest in a good reference book containing discussions of building techniques, span charts and schematic drawings explaining how the many parts of a house come together. One we've used for many years that Kevin found invaluable when he designed and we built his house in Idaho was "Principles and Practices of Residential Construction" by Joseph D. Falcone (Prentice Hall, 1987). It's full of valuable information presented clearly. There are a lot of pieces to the puzzle that is a house. It's helpful to have a handbook for reference.
Excerpt: If you decide to design the addition and draw the plans yourself, the first step is a trip to the local building department. Go with a floor plan and an elevation drawing of what you want to build. Most building departments have packets explaining the types of drawings you'll need to submit to get a building permit. Building department personnel are a great resource. They will explain the permit and inspection process and perhaps even point out some alternatives you might consider. Typically you'll have to provide a plot plan showing the house as it exists on the lot and the proposed addition with setbacks from the property line. You'll also have to submit a floor plan and one or more elevations (views of the exterior) and a framing plan showing the proposed framing of the walls and the roof, sheeting and finish siding, and roofing material. You'll probably also be asked to provide a plumbing schematic, a mechanical plan showing additions to the heating, ventilating and air-conditioning system, and an electrical diagram.