The clear R‑Value of an Fox Blocks is R22, however current Energy codes recognize the lack of thermal bridging in an ICF and the contribution of the mass concrete on the influence of the thermal performance. Whole wall calculations indicate a Fox blocks wall assembly provides an R24 rating.
The continuous double layer (inside and outside) of insulation, the elimination of thermal bridging and minimal air infiltration through the mass concrete wall assembly, allows Fox Blocks walls to performance in the high performance wall assembly category. Completing the envelope with energy efficient windows and doors and roof insulation, Fox Blocks homes can easily meet and exceed energy code requirements and exceed the minimum requirements for Energy Star and EnerGuide. A Fox Blocks structure requires 44% less energy to heat and 32% less energy to cool.
Traditional stucco has a thick cementitious base, typically installed over a metal lath. The metal lath is fastened directly to the Fox Blocks webs with screw or staples.
Fox Blocks walls are designed as reinforced concrete walls, with steel reinforcement bars specified to be installed vertically and horizontally, as the walls are built. Typical reinforcement bar sizes used are #4 or #5 (10 m or 15 m).
Fox Blocks has conducted numerous fastener tests for pull-out strength and shear capacity for various fasteners – screws, ring shank nails and staples into the plastic webs. The recommendation for interior and exterior applications of finish materials is for the use of screws which provide the best holding capacity into the plastic webs or fastening strips in the forms which are identified on each block.
The EPS insulation does not provide any holding capacity for fasteners.