Structure that requires code ordinance

Strengthening Structural Performance

Residential Design
March 04, 2026•3 min read

“Small structural changes can make a big difference. Strengthening stability, improving performance, and ensuring long-term reliability.”
- Caleb Vorpahl, StructSolve Engineering

The Situation

post in shed

A residential property owner contacted StructSolve to evaluate and revise an existing structure to improve its wind resistance and roof framing performance. The project focused on targeted structural modifications designed to enhance lateral stability and reduce roof deflection while maintaining compliance with current building codes. The scope was carefully defined to strengthen specific structural elements without requiring full structural reconstruction, allowing for efficient implementation and cost-effective improvements.

Project Scope: Required Modifications (Revisions)

roofing sketch

The required modifications focused on increasing the structure’s resistance to wind forces and improving roof framing stiffness. Cross bracing was added at the corners on the left and right elevations near the front corners of the structure to enhance lateral stability and reduce deformation under wind loading. In addition, purlins were added to reduce spacing and decrease purlin deflection. On the Roof Framing Plan, 2x4 purlins were incorporated to reduce the existing 24-inch on-center spacing to 12-inch on-center spacing, significantly increasing roof rigidity and improving load distribution. The rear elevation required no structural changes and was clearly noted as “NO MODIFICATIONS REQUIRED,” confirming that existing framing in that area met performance expectations.

Design Loads & Applicable Codes

taping the wall length

The structure was designed to Risk Category I in accordance with the current edition of the International Residential Code (IRC) and the American Wood Council National Design Specifications (AWC NDS). The design incorporated a soil bearing pressure of 1700 PSF. Roof loading criteria included a dead load of 10 PSF, a live load of 20 PSF, and a snow load of 30 PSF. Wind design was based on a basic wind speed of 105 MPH with Exposure B conditions. Deflection criteria were established as L/240 for the roof, L/90 for walls, and L/240 for headers to ensure both strength and serviceability performance under prescribed load combinations.

Concrete and Wood Notes

wall connecting to roof and structure

All concrete elements, including footings, foundation walls, and piers, were specified with a minimum 28-day compressive strength (F’c) of 4000 PSI. All framing lumber was specified as Douglas Fir #2 to provide reliable structural capacity consistent with AWC NDS design standards. Wood members in contact with concrete or masonry were required to be pressure treated to protect against moisture-related deterioration. Additionally, all fasteners used in these conditions were specified to be galvanized or stainless steel to ensure corrosion resistance and long-term durability.

The Outcome

Through the addition of cross bracing and the reduction of purlin spacing, the structure achieved improved lateral resistance and reduced roof deflection, bringing performance in line with current code requirements and serviceability limits. The revisions enhanced structural integrity while preserving the overall layout of the existing structure. By aligning the modifications with IRC and AWC NDS standards and clearly defining material and construction requirements, StructSolve Engineering delivered a solution that strengthened performance, ensured durability, and supported successful permitting and inspection approval.

Project Details

Location: Ely, Iowa
Client: Homeowner
Service: Project-Specific Design
Scope: Check the structural integrity of the dethatched structure.

designwind
I am a motivated high school student with a strong interest in engineering and community involvement. I currently serve as an intern at StructSolve Engineering, where I am gaining hands-on exposure to the engineering field while developing problem-solving, teamwork, and professional communication skills. Outside of academics and work, I am actively involved in golf and wrestling, which have helped me build discipline, resilience, and a strong work ethic. I am also an Eagle Scout in the Boy Scouts of America, an achievement that reflects my leadership experience, commitment to service, and dedication to long-term goals. Volunteering is an important part of my life, and I enjoy giving back to my community whenever possible. In my free time, I also enjoy listening to and exploring music as a creative outlet. I am eager to continue learning, growing, and applying my skills in both academic and professional environments.

Tierney Riedemann

I am a motivated high school student with a strong interest in engineering and community involvement. I currently serve as an intern at StructSolve Engineering, where I am gaining hands-on exposure to the engineering field while developing problem-solving, teamwork, and professional communication skills. Outside of academics and work, I am actively involved in golf and wrestling, which have helped me build discipline, resilience, and a strong work ethic. I am also an Eagle Scout in the Boy Scouts of America, an achievement that reflects my leadership experience, commitment to service, and dedication to long-term goals. Volunteering is an important part of my life, and I enjoy giving back to my community whenever possible. In my free time, I also enjoy listening to and exploring music as a creative outlet. I am eager to continue learning, growing, and applying my skills in both academic and professional environments.

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