Project Name: Rogue Credit Union
Location: Coos Bay, OR
Project Overview
S+B James Construction recently completed the new Rogue Credit Union branch in Coos Bay, Oregon. From the beginning, the project team recognized that the site presented subsurface challenges commonly found in coastal areas. The ground conditions required a thoughtful fill strategy that could support the slab design without placing excessive additional weight on the soils below.
To address these conditions, the team incorporated geofoam fill into the foundation assembly. This lightweight material provided a practical alternative to conventional rock, sand, or soil fill and helped the project move forward efficiently while meeting the technical needs of the site.
Challenge
Coastal soil conditions can create added complexity for foundation design and construction. At the Rogue Credit Union site, the project required fill beneath the slab, but using traditional materials would have added significant weight to the subgrade.
The team needed a solution that would:
- Reduce loading on the underlying soils
- Support the slab and foundation design
- Limit the need for heavy fill placement and compaction
- Maintain constructability in the field
- Help keep the project on schedule
Solution
Geofoam was selected as a lightweight fill material that could occupy the required void beneath the slab while significantly reducing the load placed on the subgrade.
The construction sequence included building the foundation walls, placing the geofoam blocks within the foundation area, and then pouring the slab over the top. Once complete, the geofoam was fully encapsulated within the foundation assembly, protecting it from exposure and allowing it to serve as a permanent lightweight fill material.
Although geofoam is commonly used in roadway, culvert, and infrastructure applications, it is less frequently used on local commercial building projects. For this project, however, it proved to be a strong fit.
Installation and Coordination
The geofoam blocks were large and somewhat awkward to handle, but their light weight made them much easier to move, place, and adjust than conventional fill materials. This helped reduce the labor and equipment demands typically associated with placing and compacting heavier materials.
Successful installation required close coordination with the foundation design and construction sequence. Key considerations included excavation, geogrid placement for stabilization, placement of the foam blocks, and protection of the material within the completed slab system.
By eliminating the need to place and compact large volumes of heavier fill, the team improved constructability while reducing the overall load on the foundation soils.
Results
The use of geofoam helped the project team:
- Reduce soil loading beneath the slab
- Improve field efficiency and constructability
- Avoid extensive placement and compaction of heavier fill
- Support the foundation design in challenging coastal soil conditions
- Maintain momentum in the project schedule
With favorable field conditions and strong coordination among the project team, the Rogue Credit Union branch was completed approximately one month ahead of schedule.
Benefit to Owner
For the Rogue Credit Union project in Coos Bay, geofoam provided a smart, cost-effective solution that matched the technical requirements of the site. Its lightweight properties helped address challenging soil conditions, while its ease of placement supported an efficient construction process.
The result was a successful project outcome that demonstrates how alternative fill materials can help solve site-specific challenges on commercial building projects.