The Bertelson Residence in Winterset, Iowa, is a single-family residence with 5,168 square feet of finished space built using Fox Blocks ICF. This home was the 2nd Runner Up and People’s Choice Award winner in the Large Residential category of the 2025 ICF Builder Awards. The homeowners’ goal was to build an ICF home in a historic neighborhood, featuring authentic details from the Craftsman era of architecture. The project entailed the demolition of an existing late 1800s two-story brick outbuilding, as well as the removal of large onsite trees and the preservation of large oaks on the property.

“The team adopted a 1920s Craftsman-style design to fit into the existing neighborhood while incorporating modern technology, including heated floors, geothermal heating and cooling, ICF walls, solar panels, open tail trusses, rainwater collection system, and a safe room under the wraparound front porch,” said Mike Kennaw, a representative of form manufacturer Fox Blocks by Airlite Plastics Co. The home also includes 60 yards of stamped and stained concrete, a heated driveway and carport slabs, as well as concrete porch decks.

Complexity and Creativity
The L-shape design of the 5,168-square-foot finished home with nearly 3,730 square feet of unfinished space called for 44 corners for the basement and main level, with beams to carry the partial upper level. The team engineered a special steel tube mounted to ICF walls to carry the eyebrow roof load between the main and upper-level floors. An elevated second-story concrete porch cantilevers above the concrete first-story wrap-around porch. The project also incorporates geothermal energy with 18 on-site wells. Custom quarter-sawn oak trim work and stairs, and quarter-sawn oak floors with Brazilian inlays elevate the design.

The floor plans posed a creative challenge for the project team. “The home includes an elevated second-story concrete porch that cantilevers above a concrete first-story wrap-around porch,” said Kennaw. “Additionally, the space below the first-story porch is a saferoom, accessible from the basement.” All exterior walls of the home are built with ICF construction, and 400 square feet of LiteDeck was used in the construction of the porches. The team had to think outside the box to engineer the rafters to support the second-story concrete porch and the 4-inch-wide eaves over the porches, both of which tie into the ICF system.

The project occupies the majority of the lot it was built on. In order to make space for the project on the existing site, the team acquired a variance. Existing mature trees on the property caused an additional challenge, as it was important that the trees be preserved. Other challenges included retrofitting reclaimed materials and incorporating contemporary details and systems into the building without compromising the structure’s historic Craftsman style, explained Kennaw.

“Some items from the Victorian-era home that previously occupied the lot were reclaimed for use in the new construction,” said Kennaw. “This included a stained-glass window above the entry, original bricks on the exterior facade, and re-milled woodwork utilized for interior finishes.”

Sustainability and Impact
The project incorporated 100% icynene spray foam, composed of recycled materials, in the roof. Ninety-six solar panels with battery storage and backup for the entire structure line the roof. With the wells, the monthly heating and cooling costs are under $100, which also includes the 25-by-75-foot wood shop and garage attached to the home. When possible, an HVAC economizer utilizes the cool outdoor air to cool the building instead of operating the air conditioning compressor. This reduces the strain on the cooling system.

The residence won an award at the IRMCA 2023 Concrete in Excellence banquet in the “Residential Above Grade” category. Kennaw says the homeowner was extremely pleased with the home’s energy efficiency and quietness, especially since the property is located in town, close to school traffic. The home was selected as a winner for the Excellence in Concrete for Iowa 2023 program.

The general contractor, Newcastle Enterprises, has specialized in custom ICF homes and commercial buildings for more than 30 years. The homeowners viewed a few Newcastle homes and consulted with homeowners, which sparked their interest in ICF due to all the added benefits.