What is the R-Value?
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.
Can I leave Fox Blocks forms exposed to ultraviolet rays for an extended period (months)?
Yes, but you will notice a light dusting on the surface and a yellowing discoloration of the forms. This does not indicate any detrimental effects to the ICFs. We do suggest, that if the exterior finish is not going to be installed within around a 3 month period or more, the forms be protected from UV rays by installing a temporary building wrap type material. The powdery film must be removed with soap and water before the application of a synthetic stucco finish or waterproofing membrane.
Can you vibrate or consolidate the concrete in ICFs?
Yes, consolidation of the concrete is one of the key elements in the placement of concrete in an ICF wall. Fox Blocks recommends internal vibration with a pencil vibrator, quickly in and slowly out.
Is a high performance ICF home less expensive to build than a wood framed high performance home?
Yes, marginally higher on the initial capital costs, but, it is a recorded fact that Fox Blocks high performance homes out perform in comfort and operating costs over a wood framed home. These creates monthly cost savings for the life cycle of the Fox Blocks home.
Is there a problem when placing concrete, dropping concrete from the top of the wall which may be over 8' (2.4 m)?
No. Specifications in the America Concrete Institute (ACI) do not limit the maximum distance concrete can free fall. Engineering studies and reports have shown that free fall from up to 35′ doesn’t reduce concrete quality and there is no evidence of segregation or weakened concrete strength. ICF concrete design calls for a high slump mix which assists in reducing segregation.
Does the Fox Blocks contain recycled materials?
The plastic webs in Fox Blocks forms are 100% recycled postindustrial polypropylene. The EPS insulation is virgin material. Recycled content for an ICF block is measured by weight. The recycled content by weight of a standard 6″ Fox Blocks form — 48%.
Does the EPS provide support for a wood sill plate?
No, the EPS has no structural capacity to support any loads. Wood sill plates must achieve the required bearing from the concrete within the ICF. A wood plate that cantilevers 1⁄3 over the EPS and bears 2⁄3 on the concrete is allowable. This can be done with a minimum 2 x 6 plate. If a 2 x 4 plate is required, a taper top form should be used to extend the concrete under the plate.
Is installing ICFs a DIY project?
Fox Blocks recommends that all installers using Fox Blocks ICFs complete a Fox Blocks training program to ensure they have a better understanding of the basics. However, for first time installers, it is preferred that a Fox Blocks trained, experienced installer inspect the installation prior to placement of concrete and assist in the placement of the concrete, as they are familiar with working with concrete and can ensure the build is structurally sound and safe and the walls are consolidated properly, built straight and plumb.
What if my contractor doesn’t know how to build with it?
Fox Blocks offers the most comprehensive installer training in the industry. We can train your contractor or help you locate a trained installer in your area.
Is burning EPS toxic?
Test reports conducted by the National Research Council state: “The maximum toxicity index obtained from the combustion of polystyrene was of the same order as that of wood.” Fox Blocks ICFs have been tested to meet building code requirements for flame spread ratings, smoke development and toxicity