When planning to add or modify any portions of an existing structural component of your home (i.e., walls, floor/roof framing, and foundation).
Affixing a Professional Engineer stamp to drawings or letters certifies that structures have been analyzed and are properly designed to carry the applicable building code mandated design loads.
Inspections are generally completed within a week of the request and subsequent reports are generally completed within 1-2 days of completing the inspection. Projects that require CAD-generated design drawings can take up to two months to finalize.
The most critical potential pitfalls are under-designing your new structure, undermining or overloading your existing structure, and not adequately transferring the loads to the foundation. Additionally, if you don’t meet all building construction code requirements, you can fail city permit inspections and cost yourself time and money.