When you begin the process of building your own house, many seemingly small decisions can make an enormous difference in the final product which is precisely how we felt during our ICF construction.
As we journeyed further into our debt-free homebuild, we decided to build the basement of our home with insulated concrete forms (ICFs). Though ICF construction was more work up front, we couldn’t be happier with our decision to choose a material that let us build stronger, more durable, and more insulating walls for our timberframe home.
This article will go through our experience with ICF construction so that you can take the lessons that we learned and apply them to your own home build.
What are Insulating Concrete Forms?
ICF construction relies on insulating concrete forms, which are hollow foam bricks that are stacked into the shape of your building’s exterior walls.
Once in place, they are reinforced with steel rebar and filled with concrete to create a wall system that is incredibly strong, soundproof, and thermally insulating.
ICF blocks come as interlocking modular units that are meant to be stacked together, a little like Legos. You don’t need mortar to hold the blocks together; the added concrete does the job perfectly.
Thanks to its energy efficiency and ability to absorb shock, ICF construction is popular for buildings in disaster-prone areas. We might not be at risk for hurricanes where we live, but it still appealed to us to prioritize energy efficiency while building our home.
Pros & Cons of ICF Construction
If you look through the websites and customer reviews of different ICF block companies the benefits of ICF construction stand out.
Such things include:
- Natural Appearance: When you build your home with ICF blocks, you can cover the exterior with brick, rock, stucco, siding, or any other desired material. No one but you will know that the interior is ICF construction.
- Greater Structural Strength: With ICF construction, you get the double benefit of a reinforced concrete wall with the insulation qualities of a foam interior. This allows ICF walls to better withstand hurricanes, earthquakes, and other events that might leave lesser foundations cracked.
- More Insulating: ICF walls consist of concrete surrounded by foam, meaning that heat energy is retained within the concrete center and directed into the ground of your building. Overall, estimates show that this leads to a 30-70 percent savings in energy costs, 75 percent reduction in dust and allergens, and a significantly more soundproof wall than other forms of construction.
- Protect the Concrete: One of the worst things that can happen in a home is having the concrete in foundation walls weaken, crack, or shift. ICF construction lowers this risk because the concrete is protected within foam bricks that insulate it from environmental factors that would cause it to be stressed.
Are there any negatives to ICF construction? In a word, the cost.
You can expect to pay about forty percent more for your foundation than with conventional methods. However, instead of the bare concrete wall, ICF building provides you with a valuable insulated wall with a vapor barrier, benefiting your home in the long run.
How Our ICF Home Build Went
No building project is ever completed without some bumps along the way, and our ICF construction process was no different!
Our First Big Problem: The Common Seam
While it’s apparently common knowledge to seasoned builders that insulating concrete forms won’t fit together perfectly, we rookie workers expected them to fit together as tightly as a Lego set within our 36×36 footprint.
In reality, you need to start the blocks from two corners and cut a block to fit the gap where they meet up. This creates a ‘seam’ up the wall that needs to be filled with expanding foam to keep it secure.
Unfortunately for us, we didn’t realize this until adding the second level of blocks made it clear that the keys won’t fit together. It took us hours of wasted time to figure this out, and the result is that our building is a full inch larger on every side than in our plans, and the installation took days longer than it should have.
So, learn from us, and read the instructions carefully before you begin!
NOTE: We did our icf construction in 100+ degree heat (Fahrenheit). Wearing the appropriate construction work clothes was critical.
The Zont & Zuckle ICF Bracing System
The Zont and Zuckle bracing system is an aligner designed specifically for ICF walls. It is a way of creating super straight walls by aligning everything both vertically and horizontally. This ensures you have an excellent foundation to build your home on top of.
For us, this bracing took longer than stacking the ICF blocks in the first place. The entire process required tons of lumber, and the natural warping within it only succeeded in frustrating the process further. You can watch the struggle in this video.
Plumbing ICF Walls
Just because your ICF walls are stacked and braced doesn’t mean that your walls are plumb. They will likely lean in or out… ours leaned in.
To plumb the walls all you need to do is twist the Zuckles and so long as your bracing system is in-place correctly, the lumber that is attached to the Zuckles will push your walls out (or pull them in) to make them plumb.
It took us a little while to get in the groove on plumbing our icf walls but in the end it probably took us a couple of hours to make sure they were perfect.
Reinforcing Walls Before Pouring
Another lesson we learned is that it’s often necessary to cut out the plastic reinforcers between blocks in ICF construction, even though this weakens the blocks. We had to do this on the first row to place our bended rebar around the corner.
To restore their structural integrity and prevent blowouts, we reinforced these weak spots with plywood. In fact, we used plywood on our garage door openings, on the buttress and buttress opening, and anywhere we cut ICF bricks apart to improve their fit.
We’re happy to report that we had zero blowouts during the pour so our reinforcing worked!
Pouring ICF Walls
In most cases, concrete pour day is one of the most exciting days of ICF construction. The walls are stacked straight, and it’s time to celebrate by cementing them into place.
However, it’s also the time when mistakes become permanent and can have enormous implications for the project going forward. Talk about pressure!
Thanks to all our prep work, pouring concrete for our ICF walls couldn’t have gone smoother. We owe a lot of thanks to the guys responsible for the pour; without their expertise and guidance we might have made small mistakes that could have been disastrous.
This video captures our triumph well.
Our ICF Construction Playlist
We’ve documented our home build on YouTube so that you can follow the entire ICF construction process in video form! While this project was a lot to tackle for first-time home builders, the result is a beautiful basement we couldn’t be prouder of.
Want to Follow Our Homebuild Progress?
Our timber frame home build is only just beginning, as we want you along for the adventure. Be sure to follow us on our blog, Facebook, Instagram, and our YouTube channel. We share different content on every medium, so it’s worthwhile to follow them all.
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