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.
How do you control voids in the wall?
The concrete mix is a high slump 5″- 6.5″ (125 mm – 165 mm) with a smaller aggregate size so the concrete flows easily. The person in charge of placing the concrete should watch the concrete flow throughout the whole wall to ensure there are no void pockets. Internal vibrating provides good consolidation, eliminating voids.
How are Fox Blocks green/environmentally friendly?
Fox Blocks contain a minimum of 40% recycled content by weight.
- Fox Blocks do not off-gas and are not manufactured using any gases that deplete the ozone or are harmful to the environment.
- Fox Blocks require low embodied energy to manufacture.
- Fox Blocks do not contain any materials, that promote mold or mildew growth.
- Fox Blocks are an efficient construction method thereby reducing the amount of construction waste, dust and air pollution in the building process.
- Building with Fox Blocks will save on heating and cooling costs because less air is exchanged between the outside and inside of your home. This also means a smaller more efficient HVAC unit is required for the home.
- Fox Blocks are sustainable. They will not rot or deteriorate for the life of your home.
- Fox Blocks provide a secure, durable, comfortable, long lasting building
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.
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 a vapor barrier required on the inside face of an ICF wall?
No. The characteristics of an ICF wall with the mass concrete and the EPS insulation provide the required vapor permeance to meet building code requirements as a vapor barrier.
Do you need special code approvals to build with Fox Blocks ICFs?
No, ICFs in general are covered in the building code and Fox Blocks ICF has a product evaluation report that confirms the product and applications meet the requirements of the respective building codes in the USA and Canada. These reports are available on our website.
Do I have to finish my basement walls with drywall?
All building codes in the USA and Canada specify that plastic insulation (EPS) must be covered by a thermal barrier equivalent to 15 minutes of fire protection in habitable spaces. If the basement is classified as habitable space, then gypsum board must be applied but does have to taped and filled. Check with your local building official.
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.