The Benefits of ICF Bucking.

If you’ve spent any time researching Insulating Concrete Forms (ICFs) you probably know a few things.

• They create walls that are incredibly strong
• They provide a high R-Value (Check out this story to learn more)
• They create “tight” structures with low air infiltration
• They make homes that nearly soundproof

As an ICF manufacturer, we tend to focus on all of the benefits. I mean, why not, right? There are so many! And while we believe (and science is proving (https://buildblock.com/performance/) that ICFs are the best way to build, that doesn’t mean that there aren’t challenging areas in any ICF structure where those benefits might be trickier to achieve. So let’s talk about one; door and window openings.

In just about any structure, the doors and windows are the areas where you can feel a difference between inside and outside temperatures the most. This is called thermal bridging, where the heat or cool from either inside or outside “bridges” the gap in the wall. Thermal bridging can create a home that transfers warmth in the summer and cold in the winter, causing HVAC units that run more often.

Is this most prominent in wood structures?
Absolutely.

Is it still an issue in ICF structures? 
It sure can be.

What is Bucking?

When it comes to insulation, ICFs provide continuous insulation on both sides of a concrete wall. You can read more about the insulation properties of ICFs in this 4 part series. So let’s forget about wood for now

and assume that you’ve made the smart choice to build with ICFs. You know that your home is going to be quiet, strong, and energy efficient but there is still a danger of air leakage around the areas of your home that aren’t insulated well. A prime example of this is your openings.

When building with ICFs, it is necessary to “buck” all rough opening. This keeps the concrete from flowing out of the walls when they are poured and provides attachment points for your future door or window. There are several types of materials that can be used as bucking. The most common are wood, vinyl, pressure treated lumber, and ICF foam bucking.

Weighing Your Options

I know I said, “let’s forget about wood” but here we are. Let’s dissect how wood performs as bucking in an ICF structure… pretty much the same as it does in a wood framed house. That was easy! Yes, wood will keep

concrete in the wall and it provides a fine attachment point but provides very little insulation value.  If you’re already building more efficiently with ICFs, why let that go to waste by adding a nice wooden (thermal) bridge around your windows? Strike One.

The same can said for vinyl bucking. Plastics, much like wood, create nice attachment points but are a very poor insulator. Strike two.

As a leading ICF manufacturer, we want to be able to provide you with everything you need to make your project a success. The issue of thermal bridging around openings is an industry problem, so we developed a solution. BuildBuck ICF bucking brings the insulation properties of EPS foam together with embedded plastic webs to create a strong, seamless transition from BuildBlock walls to door and window openings. The plastic webs inside the buck provide superior attachment points and BuildBuck comes standard with the many features that you already love about BuildBlock (tape measure, numbered cut lines, integrated sealing member etc.). We know how well ICFs perform in terms of energy efficiency, sound mitigation, and air infiltration so an ICF buck is clearly the best choice when finishing every aspect of your ICF home. Home Run!

Cost Comparison 

Ok, I’m convinced. So now I have to take out a second mortgage, right? 
Of course not!

When you take into account the ever-changing (and ever-rising) cost of lumber, foam bucking does not come at a drastically higher price. In many cases, it is either cheaper or similar to the cost of wood. Plus, BuildBuck ships flat on top of the bundled BuildBlock that you’re already ordering, so there is usually no added shipping cost. It’s an easy addition to any order that adds little to no cost to the overall budget of the project. You can learn more about the benefits of ICF bucking here.