The Insulated Concrete Wall Form system is a stay-in-place formwork (ICF) that is used to hold a structural grid of concrete and steel in place until cured. Concrete strength and steel requirements are designed by licensed engineers in accordance with applicable design codes (CAN/CSA A23.3 in Canada, ACI 318 in the USA). The Nexcem material itself does not contribute to the overall strength or load carrying capacity of the wall. Once the concrete has cured, the Nexcem material has served the structural function of containing the concrete and withstanding hydrostatic pressures induced by the wet concrete. After curing, Nexcem does continue to serve the following functions:
– Provides integral continuous insulation layer with majority of insulation positioned on the exterior.
– Provides a fire resistant surface/finish (Class A/1 material that can be left exposed if desired).
– Provides a Surface for other finishes (any type of interior/exterior finish can be applied)
– Provides Thermal Mass (Primarily from the presence of the concrete core)
– Provides Hygric Mass (Primarily from the presence of the Nexcem material).
The Nexcem wall assembly will typically have a permeance ranging between 40 – 100 ng/(Pa.s.m2), depending on interior and exterior finishes. Although this is not necessarily “uncontrolled” vapour diffusion, it is a vapour permeable when compared to conventional construction. This vapour permeability will provide a more dynamic humidity control – when used in conjunction with hygric mass materials (such as Nexcem) and wall components that are not adversely affected by vapour diffusion (such as concrete and Nexcem).
Integral to the desired performance of the Nexcem wall system is the inclusion of a continuous air barrier. The majority of thermal performance problems and related moisture / condensation problems, occur as a result of air leakage and not vapour diffusion. The Nexcem wall assembly, by itself does not serve as an adequate air barrier and one must be incorporated into the wall assembly. This is typically achieved, by one of the following methods:
– Continuous cement basecoat (Parge coat) applied to the exterior surface of the Nexcem material
– Continuous multiple coat exterior stucco systems (synthetic or natural stucco).
– Exterior applied air membrane products (housewrap or other)
– Interior airtight drywall approach (ADA).
– Spray applied insulation
Contact us for more information or for a no obligation quote for your building project.