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Welcome to the About ICFs blog by NUDURA Insulated Concrete Forms. Here you will learn more about how ICFs began, What ICFs are, how to use custom forms to meet design requirements, information about installation and more. Be sure to check back regularly!

What are ICFs?

by NUDURA Blogger | May 02, 2016

Insulated concrete forms (ICFs) offer energy efficiency, comfort, safety and faster construction, in addition to a number of other benefits that contribute to the bottom line for builders and homeowners. They’re becoming increasingly popular as architects around the globe recognize the windfalls of the technology.

In fact, according to market research conducted in 2015, the global market has been growing at between 25 and 30 percent annually, and the arrow is pointing up for future construction activity, especially in North America.

So what are ICFs?

At their most basic level, ICFs consist of two panels of EPS foam with a hollow core in 6' Standard ICF Blockbetween. The panels are held tightly and firmly in position at regular intervals by plastic webs, and can be stacked on top of each other in a fashion similar to Lego blocks.

Diving into more detail, panel sizes and core thicknesses vary from manufacturer to manufacturer. Standard NUDURA panels are eight feet long by 18 inches tall, and offered in core thicknesses of 4-, 6-, 8-, 10- and 12-inches. The common workhorse form, however, is more along the lines of four feet long with a 2 ½ to 2 5/8 -inch panel thickness and 6-inch core.

Using those standard numbers, typical wall thickness using ICFs is slightly more than 11 inches, which makes these buildings arguably the tightest in existence today. We’ve conducted blower door tests on many of our completed ICF buildings and found they allow fewer than .3 air changes per hour. Therefore, we often recommend using energy recovery ventilators to ensure safe air exchange, and that fresh air enters the building without losing heated or cooled air.


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  1. Rodger Mullins | May 29, 2019
    What is the toxicity and fire rating of this material.
  2. Peter Therin | Aug 30, 2018
    From the article it is clear that it prevents spread of fires from one building to another. Provided they use insulated concrete forms (ICF).
  3. Cliff | Dec 31, 2017

    I have a question. How difficult is it to go with a concrete roof that could be utilized similar for outdoor activities, similar to those used by folks in more southern climes or in commercial applications here.

    Assuming that the concrete roof application you are proposing above is a typical FLAT ROOF or patio (or as stated – “in commercial construction”)  is not difficult at all. Almost any type of concrete slab system can be interfaced with NUDURA Walls, be it – Hollow Core Precast, Cast In Place Slab or even composite steel deck with cast in place slabs as well as proprietary Insulated Concrete Floor Slab Systems can be used.

    As for sloped concrete roofs- these are more complicated and though they can also be interfaced with NUDURA Walls, they require proper professional engineering design along with careful concrete placement with low slump concrete in order to be able to work effectively.

    - NUDURA Blogger | January 3, 2018

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