Structural engineering — wall removals, addition framing, tie-in

What's different about this engineering scope

A whole-house remodel + addition is dominated by horizontal load redistribution: every interior wall you remove is a former bearing wall that needs a beam, posts, and a load path to the foundation, plus a new addition that has to integrate without differential settlement.

What the engineer designs

A WA-licensed PE designs:

1. Addition foundation per the tie-in strategy from step 1.3.
2. Addition framing — floor joists, exterior wall framing, roof framing.
3. Roof tie-in to the existing house.
4. Interior wall-removal beams — LVL, steel, or glulam sized to the span and load, with posts and a continuous load path to the foundation.
5. Lateral work if WSEC or seismic analysis triggers it — retrofit shear walls and holdowns if the project trips the energy upgrade threshold.

Renton-specific: Coal Mine Hazard design requirements

If your lot is in a Coal Mine Hazard Area, the engineer incorporates the geotech report findings into the foundation design. Per RMC 4-3-050, Renton CED may require independent review of geotech findings for critical facilities in high CMH areas, at the applicant's expense. Confirm this requirement at the pre-application meeting.

When this is done

When you have a stamped structural set that the designer has integrated into the architectural drawings without conflict. The combined set is permit-ready pending the energy compliance analysis.