Do I Need a Structural Engineer for an Addition?

Quick Answer

Yes — building additions almost always require structural engineering. An addition adds new structural loads that must be designed and connected to the existing structure. The building permit for an addition typically requires structural drawings and calculations stamped by a licensed structural or civil engineer.

What Structural Engineering an Addition Requires

New structural framing design — walls, roof, floor system
Foundation design for the addition
Connection design where the addition attaches to the existing building
Evaluation of the existing building's capacity to handle the new connection loads
Seismic and wind design for the addition
Structural permit drawings and calculations
Geotechnical coordination if significant new foundation loads are involved

Existing Building Evaluation Often Required

The structural engineer evaluates the existing building at the point of connection
If the existing building lacks original drawings, field verification may be required
Some additions require strengthening the existing structure to carry new loads
If the addition triggers a change in seismic design category, the whole building may require review

Starting an Addition Project

Locate existing drawings — contact your building department if you don't have them
Engage an architect for the addition design before structural engineering begins
Order geotechnical if there's no existing report on file
Contact us with architectural plans for a structural engineering proposal

Ready to Get Started?

Send us your project details and we'll respond with a proposal within one business day.

Send Your Addition Plans for Engineering Review 480-490-0064