Our experience is that clients request so many changes to stock plans that you are better off beginning from scratch with us designing a solution that truly meets your needs and goals. When we design a project we take advantage of qualities specific to your site like solar access (so important in Seattle!), topography (slope), views, and other site specific factors that stock plans cannot address. Our experience is that the investment in a well conceived architectural design will add greater value to the finished project and will be better suited to its inhabitants.
Additionally, with the many differing requirements of local jurisdictions, it is difficult for stock plans to address the requirements of local building departments. For example, projects constructed in Seattle and other regions often must meet local energy code requirements and certain structural requirements to be sure your structure will resist lateral loads from an earthquake or strong winds. Often times a stamped set of structural calculations is required to be submitted to the building department (Seattle almost always requires this for larger additions and new construction). Every jurisdiction has its own Land Use Code that specifies setbacks, height limits and a host of other code requirements. Rarely are any of these provided or addressed with stock plans purchased from websites or plan books. We feel you will get a better design and one that is uniquely suited to you and your site if you hire an Architect.