How to Plan & Design a Home Addition

Measure allowable yard space. Develop a tentative sketch for the addition to define how it will fit the house. Take into account any obstacles, such as a garage or large trees, that will be in the way. Define the square footage for the addition and its basic shape.

Figure out the roof lines. Draw the roof of the addition to harmonize with the home's existing roof. Keep the roof line simple, if possible, for the added space. Use multiple roof lines or sketch dormer windows if this works best with the home's architectural style. Draw house overhangs for the addition to blend well with existing overhangs, so the new space does not look like an afterthought.

Plan how the addition will connect to the house. Look carefully at the home's interior walls, foundation and exterior overhangs to figure out the attachment of the new addition. Decide how the new space will physically open to the facade of the existing house. Will you include a hallway? Will you build a wide doorway to connect the addition to living space? Draw the interior of the house in detail with the new addition.

Look at all electrical wiring and plumbing issues. Figure out any special needs, such as a larger heat pump or extra bathroom space required for the addition. Create routing for wiring, pipes and drains in the blueprint drawings. Plan to add an additional breaker box or increase the wiring load for the existing breaker box. Look at needs for exterior lighting for a new porch entry or yard lighting for the project.

Draw a detailed floor plan. Sketch the exterior of the addition and the interior on graph paper. Visit city officials to obtain a building permit. Inquire about codes and restrictions on building near property lines. Ask if neighbors must receive notification of the building process.