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Insulated Composite Concrete Forms (ICCF) Construction

Insulated concrete forms have long been the go-to alternative to lumber building projects, but do the latest developments in ICF technology make the old technology obsolete? Composite ICCF are insulated concrete forms made from a composite blend of recycled expanded polystyrene foam (EPS) and a grid system of concrete to create a wall. The result is a stronger, renewable, & lightweight concrete form that simplifies the building process. Here at PSE Consulting Engineers, we are firm advocates for many sustainable building practices, but the benefits of ICCF grid-screen have undoubtedly cemented these concrete forms amongst our favorites.

Note: Other brands of ICCF blocks may use polystyrene only.

Why build with Insulated Composite Concrete Forms (ICCF)?

Ease of Construction

The simple-to-use nature of ICCF grid-screen means you can save time + money on your next job. Improved size and reduced weight means individual crew-members can lift and stack these concrete forms with ease, while the large uniform dimensions allow for quick progress when you build. Custom building is also a breeze because ICCF grid-screens don’t require specialized equipment, and builders can cut them with most standard carpentry tools. Their design versatility allows ICCF blocks to be cut and shaped into unique and infinite load and non-load bearing features. These benefits translate to less labor, time and materials needed to get the job done.

Complete Disaster Resistance:

While traditional lumber builds offer no fire resistance and ICF offer some, there is no match for the level of fire, wind, and seismic resistance you get with ICCF grid screens. When exposed under extreme heat, the expanded polystyrene foam that lines a standard insulated form quickly. However, the composite material of an ICCF block is highly fire-resistant up to 4000 degrees and offers your structure 4+ hours of fire protection. Likewise, ICCF can be engineered to protect against 8.0 seismic earthquakes and stand against winds up to 250+ Mph. Protect your next build from unexpected disasters and build with ICCF.

Pest & Mold Resistant

Every day, pests and mold threaten thousands of homes in the U.S., and when they take hold somewhere, it can cost thousands to get rid of them. ICCF offers a 100% completely mold-resistant building option, making them especially ideal in warm and moist climates. The solid and seamless finished product you get with ICCF prevents pests like termites and rats from infiltrating the structure.

Composite Concrete (ICCF) is sustainable + renewable:

Composite mixture is only made from recycled and renewable materials
ICCF Blocks can be moved by hand, eliminating the need for specialized equipment
Designated corner pieces and standardized sizes help minimize wasted materials
Save up to 60% on utility bills with the use of insulated form
Excellent for large-scale commercial buildings that experience high-energy use
Finished products are extremely energy-efficient

Structural Design

Most ICCF grid-screens come in block sizes of 6”, 8”, and 10”. The blocks can consist of wall blocks, end blocks and corner blocks. Often, the 6” block will be used for interior walls and fences. 8” blocks are great for load-bearing exterior walls.

Grid Screen Style Construction – You will often hear the term “grid screen style” during the design or construction phase when using ICCF. This refers to the grid or screen of concrete that will run throughout the walls acting as nice structural support. (see below) Although there is system for ICF & ICCF called Waffle Grid, majority of design professionals will lean in favor of the grid screen.

ICCF Grid header-
When using ICCF blocks for headers, it is best to use a minimum depth of two feet for heavy loads unless the load is light. Computer analysis is needed to determine each case.

IRC and Prescriptive Design- The IRC allows for prescriptive design of ICF systems in Seismic Design Category A, B, and C only (when the wind speed does not exeed 160 mph Exposure B or 135 mph Exposure C

Gable End Wall ICCF Wind Columns-
During times when there are strong winds, use pure concrete columns inside the gable end wall instead of wall grids. This will ensure the strength of the structure.

Stand Alone Columns –
Apart from the strength of the grid system design, sometimes there will be a special case of stand-alone columns needed for structural stability. These can be designed and manufactured in 6”, 8”, and 10” core columns.

Foundations for ICCF Walls-
For heated areas, it is recommended that the designer and contractor add insulation per both the energy consultant and the local building department.

General: The Perfect Block™ Insulated Composite Concrete Form (ICCF) Wall System is hollow core forms of a lightweight mixture of 100% recycled expanded polystyrene (EPS) ground into an aggregate, Portland cement, proprietary admixtures and water. 85% – 87% of the volume of each block is EPS and has a density between 20 and 24 pcf (320 and 380 kg/m3). The forms may be stacked horizontally or vertically. The forms are available in standard thicknesses of 6, 8, 10, and 12 inches (152, 203, 254, and 305 mm) and standard height 12 inches (305 mm). Standard length is 48” (1219 mm). The horizontal and vertical cores of the forms are filled with concrete and reinforcing steel to construct a concrete wall with vertical and horizontal “post-and-beam” members. The concrete wall consists of steel reinforced vertical and horizontal members spaced 12 inches on center (305 mm). The forms remain in place after setting of concrete and are covered with an approved exterior and interior finish material.The Perfect Block™ Insulated Composite Concrete Form (ICCF) Wall System consists of individual blocks that form a permanent formwork system for reinforced concrete beams, lintels, walls, foundation walls and retaining walls. Walls constructed as described in this report are permitted to be used as load-bearing and non-load bearing walls resisting axial, racking and transverse loads in Type II, III and Type V construction in accordance with 2012 and 2015 IBC and IRC. The Perfect Block™ ICCF Wall System is also classified as a 4-hour fire-resistance rated, load-bearing wall when constructed in accordance with this report. See Figures 1,2, and 3 for The Perfect Block™ ICCF Wall System construction details.

Design: The Perfect Block™ ICCF Wall Systems forms are described as screen-grid ICF wall systems in Chapter 6, Section 611, Exterior Concrete Wall Construction of the 2012 International Residential Code© and. Chapter 6, Section 608, Exterior Concrete Wall Construction of the 2015 International Residential Code©. The Perfect Block™ screen-grid ICF forms’ core spacings are 12 inches (305 mm) on center. The Perfect Block™ forms are to be designed in accordance with Eco Building Systems Corp. Technical Building Manual ©, 2022, Edition.

Build Your Next Project With Insulated Composite Concrete Forms

The staff at PSE loves sustainable building & structural engineering, and we believe that ICCF grid-screens offer a great way to achieve it. There is a longstanding notion that you have to sacrifice durability for sustainability and ICCF is a clear exception. Contact PSE today for more information on our sustainable engineering and explore all the options available to you!

For more information, feel free to visit our structural engineering services page, or contact us