Insulating concrete form (ICF) construction uses a system of formwork to create reinforced concrete. This process is usually made using a rigid thermal insulation that can stay in place as a permanent substrate on the exterior or interior of a structure. It is used for roofing, flooring, and walls in the construction industry. The best way to think about its use is to compare each block to a Lego brick that you can eventually piece together to create the structure that you want.
Because there are stringent energy-efficiency rules to follow today, more contractors are turning to ICF construction as a way to create buildings that meet the current codes. This structure is naturally more resistant to natural disasters as well, and it is useful in applications where there is a need for frost-protected shallow foundations.
The first slabs of concrete formed to create the ICF process were invented in 1983. Now there are more than 20 million systems around the world which use this technology to provide thermal insulation, soundproofing, and improvements in the indoor air quality. These are the pros and cons to consider if you are thinking about adding this option to your next project.
List of the Pros of ICF Construction
1. It improves the structure strength of the final product.
When you are using ICF construction, then your primary advantage is an increase in the structural strength of your reinforced concrete wall. You are using one simple operation to create all of the structural qualities of concrete with the insulation and air-sealing qualities of a SIPS wall when you do it correctly. Because half of the insulation of an ICF product has its insulation on each side of the thermal mass, a significant portion of the energy it receives goes to the ground through its footings.
2. This method uses less concrete than traditional methods to complete a project.
You will often see ICF construction projects using a waffle-style blueprint for the project because the design uses about 10% less concrete than if you build a straight-form option. Even if you prefer the straight-form blocks when putting together a structure, you will develop more strength with six inches of concrete compared to an 8-inch traditional wall. That means you can save up to 25% of the materials and cost when pursuing this method, reduce your overall curing time, and provide more reinforcement to the overall structure.
3. ICF construction can save you a lot of time when building structures.
The speed at which ICFs are set is a tremendous advantage to contractors because you can essentially pour and go with the forms. You don’t need to worry about stripping and cleaning the forms once you’re ready to continue with the project. Although this process does cost a little more than the traditional building methods with concrete, the amount of labor that you save using this process will usually make up the difference – especially when you add in the cost of the alternative insulation methods in use.
4. You can still install your plumbing and wiring with the ICF method.
Wiring and plumbing are not a problem with ICF construction because the foam is thick enough that a contractor can groove it out to install the necessary items. The wires or pipes go through the wall or segment as they would in any other structure, and then spray-foam insulation will help to secure any potential leaks that occur with the installation process. That design element is why this method is so useful for closed crawl space designs, basement homes, and areas in the tropic wear heat and moisture resistance are so necessary.
5. The ICF process still uses steel rebar to reinforce the structure.
Once all of the large foam blocks are in place for a wall, builders will place steel rebar throughout the structure before pouring the concrete so that it provides the strength that is necessary for the building or project in question. Each unit interlocks with the other so that you can stack them together with little effort. You don’t need mortar to finish the project either because the concrete works to keep the items in place without any help. Since this structure absorbs shock exceptionally well, it becomes a useful tool in high-risk areas around the world.
6. It provides a structure with a natural appearance.
Because the concrete is inside of the foam blocks that are used for the structure of a project, you can create a natural appearance for the exterior of your wall. Rock, brick, stucco, and most forms of siding all work with the ICF construction process. Once you build upward with these exterior elements, only you and the contractor will know what the material behind the product happens to be. That means you can receive three tiers of strength: the exterior addition, the reinforced concrete, and the foam interior. This structure is why it is so difficult for a foundation built using this process to crack.
7. This method improves the indoor air quality of a home or building.
Because an ICF wall consists of concrete that is surrounded entirely by foam, there is less overall air movement from the exterior of the structure to the indoor environment. That means you can receive up to a 70% increase in the energy costs once the work is complete. You will also experience a 75% reduction in the levels of allergens and dust that are present inside. Since you have better soundproofing with ICFs as well, you will feel like there is a genuine separation between what happens outside and the events that occur inside.
8. ICFs help to protect the concrete better.
When the foundation of a home begins to weaken, shift, and crack, then the strength of the structure can become problematic at times. Although this issue can affect ICFs, the insulating concrete form protects the interior material more consistently by distributing stressors on the wall throughout the structure.
List of the Cons of ICF Construction
1. ICF construction works best in hot climates.
When you have the energy transfer that occurs with a concrete structure using the ICF construction technique, the heat is what transfers down at out through the anchors or footings of the unit. That process is useful in hot climates when you don’t want the outside temperatures to impact the interior climate of the structure. If you are in a cold climate, then this technology is almost worthless because the heat from inside would go through the same process.
2. You can still release the structure too early.
ICF structures typically develop more strength because the product is left in the form forever. You simply insert the product to where you will use it. Designers often mandate that concrete walls be thicker than normal because contractors tend to expose the product after just 24 hours after it is poured, which is standard for the construction industry. Even though the material stays in the form, trying to build on top of it prematurely can lead to quality problems as well.
3. The cost of an ICF wall is an issue to consider.
You can expect to pay at least 40% more for your concrete walls if you use this method of building instead of the conventional process. You’ll have more insulation and create a vapor barrier with its presence, but it can be an expensive experience if you are building a tall structure. If there is only one contractor in the area who provides this service, then your expenses might be even higher because of the scarcity of the labor. You will want to call ahead and receive quotes for an ICF construction project first so that you can know what to expect with your budget.
4. You will need to deal with the common seam in the wall.
It is not unusual for first-time contractors working with ICFs to think that the structure should fit together perfectly like a set of Legos. The building process is closer to what you would experience when laying a deck or patio. You’ll need to work from the corners of your design toward the middle and then cut a block to fit the final gap where your two lines meet up. This building process then creates a seam in the structure that requires expanding foam to help secure it. If your builder fails to follow this process, then the strength advantages that come with ICF construction could disappear.
5. There is a bracing process you must follow to keep the walls straight.
Most ICF construction projects use what is called the Zont and Zuckle bracing system. This aligner works specifically for walls using the insulating concrete form design. You must take the time to align the vertical and horizontal access with these frames to ensure that the structure you created is square. It is not unusual for the framing process to take even longer than the foam stacking work. Even then, it is not unusual for your walls to lean in or out once you get the bracing installed. Then you’ll need to make adjustments until your measurements come out plumb.
6. The rebar may not always work with the plastic reinforcers between the blocks.
The foam blocks that are used for the insulating concrete form building process come with plastic reinforcers that help to stabilize the structure. Since you also need to add steel rebar to the wall to provide it with the strength it requires, you may find that some of the elements may not work with each other. This problem happens most often along the corners of your walls. You’ll need to restore the structural integrity of the blocks if you need to go through one in some way or the concrete could cause a blowout during the pouring work.
7. You might need to trim down the blocks to make them fit correctly.
Although the blocks in ICF construction should fit together well, slight changes in the manufacturing process or dings during shipment can cause imperfections in the foam. Since you must achieve the tightest fit possible, it may be necessary to do some cumbersome trim work on some of the blocks. If you make an error in this sequence, then you could create a situation where the concrete could leak out of the form during the pour.
The pros and cons of ICF construction depend on where you plan to build a structure. Hot, sticky climates benefit the most from this process because it traps heat and filters it away without letting moisture come through it. You may find that it becomes a headache too when pouring since any mistakes will become known immediately. This process may cost more, but the benefits typically outweigh the negatives unless you live in a cold environment.
Brandon Miller has a B.A. from the University of Texas at Austin. He is a seasoned writer who has written over one hundred articles, which have been read by over 500,000 people. If you have any comments or concerns about this blog post, then please contact the Green Garage team here.