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The History of ICFs

All About the History of Insulating Concrete Forms in North American Concrete Construction from 1953 to 2018

The History of ICFs | Green Harbor Building Systems GA

To start, we should probably explain about concrete construction, and the different types of formwork available before zoning in on the history of ICF or Insulating Concrete Forms themselves. Historically the suitability of concrete as a construction material was first recognized by the Romans, with many large structures constructed with concrete including the Pantheon and the Colosseum in Rome. Surprisingly the sophisticated Romans were also the first to use Air Heated Radiant Floors as heating in their Villas which were constructed on a suspended concrete slab which allowed them to incorporate a hypocaust heating system underneath. The Romans appreciated concrete for its superior strength, fire resistance, thermal mass and its flexibility – much as folks have again started to today! How else could they have constructed the world’s largest unreinforced concrete dome in the Pantheon? To achieve this amazing feat of early concrete construction using what is basically a fluid and malleable material, the Romans also had to invent Concrete Molds – but things on that front have become a little more sophisticated since then – and these early molds (or moulds, for the Europeans) have developed into what is now generally referred to as Concrete Forms or Formwork whose purpose is to hold the liquid concrete securely in place whilst it chemically hardens into its finished form.


The Principal Formwork and Concrete Form Types Historically in Use in the USA & Canada:

1. Timber Formwork. This type of concrete formwork is the oldest and most simple, built on site out of timber, plywood or moisture-resistant particleboard and whilst easy to produce and completely flexible it is time-consuming for larger structures. Concrete formed using timber can also result in a highly irregular surface finish, and whilst some Architects and House Designers use this to great effect, it involves much planning, attention to detail and time. Another inconvenience is that the plywood and timber is often mono-use involving added costs for any construction and producing a lot of waste materials that must be disposed of. Additionally, in most applications for construction of habitable dwellings secondary insulation will have to be added later – also adding to the time and cost of construction. Timber formwork is still used principally where labour costs are lower than the costs involved in procuring and setting up reusable formwork or as it’s the most flexible type of formwork, where complicated sections of construction need a custom forming solution. It is also common historically to combine timber formwork with some type of Engineered Formwork to cover transitions or the variable aspects of day to day construction.

2. Heavy Duty Engineered Concrete Formwork Systems. This type of standardized formwork is built out of prefabricated panels usually supported by a steel or aluminum frame covered on the side to be formed with a reusable material having the desired finished surface structure. Historically speaking the two major advantages of prefabricated formwork systems, compared to the more traditional timber formwork, are the speed of construction (modular systems bolt, pin or clip together quickly) resulting in lower overall construction costs on major concrete construction projects. Except in an accident the frame is designed to be almost indestructible, while the covering panel surface may have to be replaced after several uses if timber or plywood based, but if the covering is made with steel, aluminum or phenolic board the form can successfully achieve several thousand uses depending on the operative’s care levels. The disadvantages of Heavy Duty Engineered Formwork systems are the capital outlay, the logistical requirements for getting the right sized forms in the right place at the right time, the equipment costs for form handling (cranes, trucks, shoring) and the precision required in matching forms to plans to ensure a perfect fit. Additionally, in most applications secondary insulation will have to be added later – also adding to the time and cost of construction. 

3. Light Duty Reusable Plastic Concrete Formwork. In more recent construction, these modular interlocking systems are frequently used to build repetitive yet individual, relatively simple concrete structures. The panels are lightweight and relatively robust and can be made from recycled plastic. They have found favor in the construction of low-cost, mass housing schemes. These types of modular buildings can also have load-bearing roofs to maximize space by stacking on top of one another. They can also be mounted on an existing flat roof concrete structure when constructed without a floor and lifted into place using a crane. 

4. Stay-In-Place Structural Concrete Formwork Systems. These types of concrete forms are usually assembled on site, often comprising prefabricated fiber reinforced plastic materials and in the shape of hollow tubes which are used to form columns and piers. The formwork remains after the concrete has cured to act as axial and shear reinforcement, as well as to protect the finished concrete and prevent adverse environmental effects over time, such as corrosion and freeze-thaw damage. 

5. Flexible Concrete Formwork. As an alternative to the rigid concrete molds described above, a recent addition to concrete forming, flexible formwork, is a system using lightweight, high strength fabric sheet materials to take advantage of the fluidity of concrete and create optimized or architecturally interesting construction shapes. Using flexible formwork for example allows the possibility of casting optimized foundations and walls together in a mono-pour technique – especially useful in areas with seismic risks or hydrostatic pressure when forming concrete basement structures and wanting to avoid problematic dry joints whilst using waterproofing admixtures. The main inconvenience with forming concrete this way is how to effectively insulate the completed structure if environmental conditions require it. 

6. Permanent Insulated Concrete Formwork or Insulating Concrete Forms. Insulating concrete forms or insulated concrete forms (ICF) are a system of formwork for reinforced concrete constructed of a rigid thermal insulation that remains in place as a permanent interior and exterior substrate for walls, floors, and roofs after the concrete within has set. The forms are interlocking modular units that are dry-stacked (without mortar) and filled with concrete by pumping and pouring it in place and can be horizontally orientated, vertically or in larger rigid panels – sometimes with the rebar pre-placed. The units lock together in a manner often compared to Lego bricks and create a concrete form for the structural walls, floors and sometimes roof of a building. ICF construction is gaining in popularity in the USA, Canada and the Caribbean for both low to medium rise commercial and high performance residential construction as more stringent energy efficiency and natural disaster resistant building codes are adopted. ICFs may also be used in severe climates in combination with frost protected shallow foundations (FPSF). 

As the Mission of Green Harbor Building Systems GA is primarily:

"Assisting, Educating & Inspiring the Residential & Commercial Building Construction Industry & Homeowners in the Southeast US to construct Better, Greener, Safer Buildings at a Lower Cost by using Superior Insulated Concrete Forms”

This article is going to concentrate on the use of Insulating Concrete Forms in Concrete Construction. First off let’s look at the different types of ICF, (covered in more depth here).

Insulating Concrete Forms are commonly categorized in two manners:

1. Organizations whose historical primary concern relates to the concrete industry classify them first by the shape of the concrete produced by the form. 

2. Organizations whose primary concern relates to the fabrication of the ICF forms themselves classify them first by the characteristics of the forming system. 

In the first category classified by concrete shape there are: 

 • Flat Wall Forming Systems 

For Flat Wall System ICFs, the concrete within the form quite simply has the shape of a flat wall of solid reinforced concrete, like the shape of a concrete wall constructed using removable concrete forms. Historically speaking the earliest commercial ICF systems were of this type. 

Grid Systems an elaborated version of ICFs designed to economize on Concrete are then further subdivided into two types of concrete forms

Screen Grid Systems

In Screen Grid System ICFs, the formed concrete has the shape of the metal in a screen wall, with both horizontal and vertical channels of reinforced concrete separated by areas of solid remain-in-place form material. 

Waffle Grid Systems 

In a Waffle Grid System of ICFs, the finished concrete inside has a hybrid shape between Screen Grid and Flat Wall systems core, with a grid of thicker reinforced concrete placed structurally and also a thinner concrete in the center areas where a screen grid would have solid ICF material. 

Post and Lintel Forming Systems 

For Post and Lintel System ICFs, the concrete has a horizontal member, called a lintel, at the top of the wall (Horizontal concrete at the bottom of the wall is often present in the form of the building's foundations or the lintel of the wall below) and vertical members, called posts, between the lintel and the surface on which the wall is supported.

Secondly, as Championed by the ICF Manufacturers, ICFs can traditionally be categorized by form characteristics:

• Block Shaped ICFs 

In Block ICFs, the exterior shape of the ICF is like that of a traditional Concrete masonry unit, although ICF blocks are often larger in size as they are made from a material having a lower weight which makes them easier to handle in a larger size. Very frequently, the edges of block ICFs are made to interlock, reducing or eliminating the need for the use of a bonding material between the blocks during initial assembly. 

• Panel Shaped ICFs 

Panel ICFs have the flat rectangular shape of a section of flat wall. They are often the height of the finished wall sections and have a width determined by the portability of the material at larger sizes and by the general usefulness of the panel size for constructing walls in relation to the building design. 

• Plank Shaped ICFs 

Plank ICF systems generally have the size of Block ICFs in one dimension and Panel ICFs in the other dimension and they can be designed for vertical, horizontal or multi-directional placement.

The History of Modern ICF Systems

The History of Modern ICF Systems for Insulating Concrete Form ConstructionSo, now we’ve established that the History of concrete construction and concrete forms started way back with the Romans, what about modern ICFs or Insulating Concrete Forms? What were the principal stages in their development, in the materials used to construct ICFs, and which types of ICFs have emerged as the market leaders over time in the Insulated Concrete Forming Industry?






  • Contrary to many poorly-researched articles regarding the history of ICFs which credit their invention to the 1960’s, or others that state that Insulating concrete forms made from a mixture of treated wood fibers and Portland cement were invented in Switzerland soon after World War II, Durisol, as the first ICF was known, was actually developed in Belgium in 1937 by the Swiss nationals August Schnell and Alex Bosshard (following on from a Dutch patent registered in 1932.) At the time, they made little impact on the construction industry but in 1938, these two men founded Durisol AG für Leichtbaustoffe in Dietikon near Zurich, Switzerland, to push this ICF’s industrial development and allowed the company to break into international markets, including the Netherlands, France, and Belgium after World War II – filling the void for a quick, cost effective and solid construction method using largely unskilled labor. Subsequent International patents followed including (According to The Canadian Patent Office Record and Register Volume 81, Issues 4-6 May 19th 1953) - Swiss Patent Application Nov 4th, 1949 Serial Number 593,899 In CH Nov 6th, 1948 and subsequently Canadian Patent 492,991 of the same date. By 1959, as reported in Barron's National Business and Financial Weekly, Volume 39, Durisol was promoted as cutting traditional construction costs by 20-30% and was already produced in 13 countries! Durisol today operates worldwide as a manufacturer of cement-bonded wood fibre products, with 14 manufacturing locations throughout the world and therefore take the crown for having invented ICFs and being used in construction worldwide for over 80 years.
  • However, many consider that modern ICFs which dominate the market for Insulating Concrete Forms worldwide in 2018 are those manufactured from EPS foam. So first of all – what is EPS and what is it made from?
  • To put it briefly, EPS or polystyrene Foam (often mistakenly called Styrofoam which is a registered brand of the DuPont Corporation for a specific and dissimilar type of Polystyrene based Extruded Foam) is manufactured from around 2% polystyrene and 98% air.
  • In detail, for the eternally curious, polystyrene was discovered in 1839 by Eduard Simon a pharmacist based in Berlin, who distilled benzoin or copalm balsam, the correct name for the resin of the American sweetgum tree (Liquidambar styraciflua) into an oily substance, a monomer that he named styrol as he referred to the resin mistakenly by the name storax (a bastardisation of the trees genus name of styrax). Several days later, Simon found that his styrol had thickened into a gel he then mistakenly called styrol oxide ("Styroloxyd") because he presumed oxidation had taken place. In 1845 Jamaican-born chemist John Buddle Blyth and German chemist August Wilhelm von Hofmann demonstrated the transformation of styrol to a gel in the absence of oxygen and they christened this "metastyrol." Subsequent chemical analysis demonstrated that this was identical to Simon's Styroloxyd and in 1866 Marcelin Berthelot correctly identified the formation of metastyrol/Styroloxyd from styrol as a process of polymerisation. Around 1946 it was realized that heating styrol starts a chain reaction producing macromolecules as contained in the thesis of German organic chemist Hermann Staudinger (1881–1965). This ultimately led to the hard clear substance produced receiving its present name of polystyrene – although most people associate the name polystyrene with what is actually and more accurately described as EPS foam.
  • Somewhat confusingly, according to the book authored by Fritz Störi entitled "The Stuff Foams Are Made of – The History of Styropor". Polystyrene, the plasticized material derived from Styrene (which whilst this is classified as a “plastic” could as seen above be of plant origin), was invented in 1930 – but BASF Expandable Polystyrene (EPS) foam (Styropor®) was invented by accident by a BASF scientist Fritz Stastny in 1949 when he was experimenting the process of using steam to expand beads and the possible commercial applications for polystyrene in general as a potential insulator for telephone cables. He left a sample of clear polystyrene in the baking oven in a shoe-polish tin, only to find after several hours what he described as “a veritable foam monster” which appeared “over the course of the next 36 hours. Like a beret, the lid of the can was perched right on top of a 10-inch-thick chunk of foam!” BASF perfected the molding process for their new plastic foam, patented it in 1952, and BASF introduced its new product Styropor® EPS to the public for the first time in 1952, at the plastics trade fair in Düsseldorf, Germany molded using steam right on the exhibition stand into the form of “the world’s lightest toy ship”. Ever since, EPS has been one of the most widely used thermal insulations in the world and is applied ever increasingly in architecturally designed, energy-efficient buildings. Its low cost, versatility and high R-value per dollar make EPS insulation the preferred product of architects, specifiers and application contractors across the country and its recyclability, chemical stability and environmental sustainability (being 98% air) is a bonus.
  • The first person accredited with combining the advantages of this modern, lightweight and insulating EPS into a Concrete Mold or Form in the late 1960s (helped by the coincidental expiration of the original patent for Durisol) was contractor Werner Gregori (or Gregory – as the newspaper Journal-Record reported at the time), a German born naturalized Canadian. Reputedly inspired by watching his kids playing on the beach at Algonquian Park in the sand - and the effectiveness of his EPS foam cooler at keeping his beer cold, he started wondering about the possibilities for an EPS foam block wall forming system used to cut construction costs, increase build speed and promote the use of unskilled labor. He filed the first North American patent for a foam concrete form or “modern Plastic” ICF in March 1966 in Canada with a block measuring 16 inches high by 48 inches long with a tongue-and-groove interlock, metal ties, and a waffle-grid core weighing only 2 ½ lbs and once these patents were granted in U.S. (Oct 24th 1968) and Canada, he showed his ideas to BASF in Germany, the creator of EPS, who developed his product ideas further with a view to expanding the international uses and sales of their EPS foam as an insulation product for construction.
  • The race was on for EPS ICF blocks! Several ICF homes were completed in North America around the same year, making it difficult to accurately say who was actually “the first” - the projects included: 

In Oakville, Ontario for Patrick “Bud” Kelly, owner of Allied Construction, using Gregory’s “Foam Form” ICF in 1969, (which led to Bud becoming a “Foam Form Canada Ltd” shareholder.)

Dow Chemical also completed a concrete filled foam building project in Sheboygan Wisconsin around the same time in conjunction with the Bemis Manufacturing Company.

Later in 1969, multi-unit townhouse residential buildings and a Catholic Sisters of the Church run school addition at Lightbourn School on Linbrook Rd. in Toronto were constructed using Foam Form ICFs and the design of the Foam Form ICF block was modified from a screen-grid design to a waffle-grid with metal ties around this time.


Publicity for Foam Form Limited and Werner Gregory it’s President was assured by an article by Bob Hallam, staff writer at the Journal-Record entitled “Oakville Firm Assumes Key Role in Development of Plastic House” which described the construction of a house “built entirely of plastics” for the 1969 Plastics Show of Canada built in conjunction with Martin Green of Design Craft Limited, Toronto and David Dempster of the Ontario Department of Trade and Development. Foam Form Limited contributed nearly 75% of the materials used in this ground-breaking home. “We are not trying to produce a cheap house” said Gregory at the time, with production of the ICF blocks having been very limited, but prophetically he also stated, “I expect once they become more widely used, they will become increasingly cheaper.” Foam Form Limited went on to have production licensees in Miami, Florida; San Juan, Puerto Rico; Japan and Germany before Gregory left the company in 1971, and his patent eventually became the property of Insulblock Systems Inc who ceased trading around 1988.

Interesting to note that a sprayed on polymer-based Stucco finish for the EPS surface of the Foam Form ICF was also developed for this revolutionary Plastic Home by the Eagle Bond Corporation.

History of ICFs - Article on Werner Gregory and Foam Form and the Plastic House


The adoption of ICF construction has steadily increased since the 1970s, though many believe it has been hampered by lack of awareness, building codes favoring stick frame construction in North America, and confusion caused by many different ICF manufacturers concentrating on selling their slightly different ICF designs rather than focusing on industry standardization and impact in the general construction market. ICF construction is now part of most building codes and accepted in most jurisdictions in the developed world.

  • During the formative years for EPS ICFs, it was verified that ICF walls could reduce heating / cooling costs by about one-third.
  • In the early 1970s, panel style ICFs were developed, as was bespoke bracing for aligning and holding in place the stacked ICF walls during concrete pouring.
  • During the 1980s and 1990s, many new North American ICF companies incorporated, with patented variations on the similar “block” theme like Foam-Form or Panel systems like Quad-Lock and Plank systems like Thermoform and Hobbs.
  • In the mid-1990s, the Insulating Concrete Form Association (ICFA) was formed with a singular vision, stated as: “Insulating Concrete Forms will become the preferred building method in North America”.
  • ICF producers continued to make improvements to their products and began training thousands of contractors in the proper techniques for installing their ICF building systems. The growth rate in sales of ICF forms increased dramatically from 50% to 100% each year until the first half of the 2000 decade at which time it began to level out to 20% to 30% each year. During this time, ICF construction of single-family homes in America constituted about 70% if the total ICF market while commercial and multi-family residential made up the remaining 30%.
  •  In April 2005, the ICF Builder Magazine, a publication created to promote the ICF industry and to educate ICF contractors and other construction trades and professional, rolls off of the presses. The ICF Builder Awards program was established later that year.
  • In 2006, many of the ICF producers staged a “Mega-Demo” at the World of Concrete to demonstrate how their respective ICF building systems are used to construct buildings. New residential housing starts (single-family & multi-family) begin a trend of significant decreases.
  • Fueled by the construction of schools in Kentucky and mid-rise apartments in Toronto, the use of ICFs in the commercial sector soared in 2007. Residential construction starts in the US in general continues in a downward direction.
  • In 2008, new construction plummets with the onset of a seven year recession. Some ICF producers like Arxx, Eco-Block, and American PolySteel merge in attempts to survive during this depressed construction era. The sag in residential building starts continues.
  • In 2009, the ICFA is disbanded. Residential ICF building reaches a valley of about 600 units per year at the beginning of the year and stays relatively flat throughout the remainder of 2009.
  • During 2010, “green building” continues to grow even in the midst of a major economic downturn. ICF producers demonstrate how the attributes of their building systems – energy-conserving, easy & fast installation, small carbon footprint, durability, and extremely low construction waste - make them a perfect green building material. Though ICF building starts in the single-family residential sector registered a small decrease during 2010, the rise in multi-family construction starts saw sufficient gains to enable a modest rise in total residential starts.
  • 2011 witnessed an increase in both the ICF single-family and multi-family residential sectors. 
  • In 2012, high-rise residential construction surges in the Kitchener/Waterloo area of Toronto as several (more than six) building projects exceeding 15 stories were in progress or had been completed. The combined residential markets record modest growth in this year.
  • In 2013, Fox Blocks acquires Reward and the assets from Formtech and Commercial Block. Later that same year, Fox purchased Arxx Corp. Steady increases in combined US residential housing starts continues.
  • 2014 witnesses the creation of the Council of ICF Industries (CICFI) to replace the ICFA that was disbanded in 2009. This institute was created by the collaboration of four of the leading ICF manufacturers – Logix, Nudura, Quad-Lock, and Superform. Combined (multi-family & single family) ICF residential building starts show a sharp increase, and during the summer, builders were completing houses (of all types of construction) at the rate of 1.12 million per year, the highest rate since November 2007. Commercial ICF construction outpaces residential – 24 million vs 20 million in total square feet of ICF forms installed per year – to continue a trend started in 2010.
  • 2015 witnessed the May launch of the ICF Builder Group, a “professional trade association formed to meet the needs of the ICF builder. Its goal is to provide valuable tools to help ICF builders to take their businesses to the next level, thus strengthening the ICF industry as a whole."

Article written by Robert J. Pierson. 2iiS Marketiing Inc.


Green Harbor Building Systems, LLC in Georgia is equipped to provide a leading ICF building system and the technical and logistical services to support the construction of the greenest, highest performing, and most-cost-effective structures on the market today. Centering our business around the Fox Blocks insulating concrete form (ICF) building system, the most versatile and among the highest quality ICF building systems, we will partner with our customers to construct new buildings in the future that will deliver performance levels in energy efficiency, natural disaster protection, fire resistance, and overall living comfort and health far superior to what can be achieved with wood frame and concrete block structures.