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What you need to know before starting your ICF build

By Justin Wallace, Technical Director, BuildBlock Building Systems 

After spending weeks and hours staring at your screen researching and weighing all of the different construction options available to you, ICFs have prevailed as the most cost-effective solution to reach your construction goals. So, what now? Putting theory into practice takes a little more time to get plans drawn and ready for permitting. So, how do you get there?  

For starters, the How-To-Build section (on provides invaluable information to guide you. There are a few things to consider now that you’re ready to begin. First, as you are designing your project, are the plans compatible with ICFs? Once drawn, what type of engineering will the project need? Are there special site conditions that might affect how you build? And with any construction project, there will be a million other questions. The best part is that you’re not the only one and many of these challenges have been asked, explored, and answered many times before. Connecting with a company and a product to help you meet your specific needs is a key first step. 

Let’s first look at your plans. Anything that can be designed for traditional wood or masonry construction, can be translated fairly closely to ICF construction with a few caveats. Wider walls don’t do tight corners as well. When you have an 11” or 13” (6” or 8” concrete core with 5” of insulation) wall system thickness, it’s difficult to do a 12” jog in the wall without needing a lot of cutting, gluing and bracing for your install crew which translates into additional cost. If your plan calls for architectural details that are less than 18”, consider using a different finish material to make that distinction, or frame out a profile on the face of the ICF wall to meet the desired aesthetic. Working through the design and finishes in advance can save you time, hassle, and cost during construction. 

Ensure cuts are straight and level before placing bucking or penetrations in the wall. Strap and brace any blocks with cut webs and common seams.

Practical design tips: 

  • Try to design a couple of feet of concrete wall at shear walls to offer support to adjacent walls. 
  • Design wall heights and footer steps in 8” intervals to efficiently use ICF forms and minimize waste. 
  • Design your structure how you want it, then cut the blocks to match. Working from corners toward a common seam makes this much easier. Trying to design a structure to fit ICF block dimensions perfectly always creates more headaches and compromises. The blocks are designed to be “cut to fit”. 
  • Adjust opening sizes accordingly when choosing flush mount or inset windows.  
  • Make sure that walls stay in the same vertical plane; so if you have an ICF wall upstairs, make sure there is an ICF wall downstairs to carry the load. 
  • If you have large openings, make sure you have enough ICF wall height above (lintel) to carry the load. 

There are many resources available online for ICF plans, any architect, designer, or draftsman can put the plans together for you, or in many cases, you can draw and submit the plans yourself. In many jurisdictions, you are even able to specify the reinforcement requirements for the walls yourself by using prescriptive design guidelines provided for free. This saves you the cost of an engineer for your wall system. And even if you do need stamped drawings, the engineer can reference our prescriptive tables to make their work easier. 

This brings us to our next topic: Engineers. 

Engineers, sometimes costly, can be worth their weight in gold. You can use prescriptive guidelines for your walls, and your light frame truss system will always come with an in-house engineered design, but you still need a good way to specify how other systems (i.e. slab floors, porches, decks, etc.) will interface with your wall system. For these and other considerations, a local licensed PE (Professional Engineer) familiar with your region can be of great benefit. The BuildBlock ICF wall system is designed fully within the scope of ACI-318, one of the most common concrete engineering codes. Your engineer won’t have to learn anything new to design using our system. 

One other important area to consider is geotechnical engineering done by a local civil engineer. This will tell you how much water (low/high water tables) is in your soil, the bearing capacity of your soil, which is the basis for the entire design, and the make-up of the soil (how well it drains) to give you requirements for the rest of your design. 

Having these areas covered as you start the design process puts you squarely on the path to a successful build. If you have any questions about these or other technical aspects of getting your project out of the ground, visit, connect with us on social media, or reach out to the BuildBlock team.