All vertical construction of 60 Bragg Hill Road was completed today with the last ICF pour. Under a crisp blue sky, the three remaining gables were infused with concrete and “topped off”. The only remaining vertical structure is the farmhouse cupola which won’t be built until the roof framing is complete. Fabricating 12x12 pitch gables with concrete is tricky. Many ICF homes avoid this step and revert to traditional wood frame construction because it is time and labor intensive. For 60 Bragg Hill, the importance of the structural and thermal integrity of the home coupled with its architectural design mandated the gables be made of concrete and steel.
What makes this a tricky process is the inverted shape of the concrete mold. As concrete is poured, the mold gets smaller and narrower making the dense mix a challenge to apply and agitate so that it settles correctly. Like the other pours before, this was a carefully orchestrated ballet between the Thompson Builders (Mark, Mike and Matt) and Jody, Forcine’s 32 meter Putzmeister concrete pump operator. This well rehearsed team delivered small bursts of number six slump concrete in the precise location at the right time. Like a parfait dessert, a predetermined level of concrete was poured and settled in each gable cavity. Then custom-built reinforced end caps were installed on the sloped edges of gables to define the mold for the next layer of concrete. This process was repeated four times in a rotating sequence until the three gables were completely filled with concrete and sealed.