ICF vs. Conventional Foundations
Foundations - arguably the most important piece of a home. The strength and durability of a home's foundation usually sets a precedence for the rest of the home. If the top of the foundation walls are straight, then it makes framing easier and straighter, and vice-versa. If the walls themselves are straight, then finishing the basement is easier when it comes time to frame out the outer walls. If the walls are solid, it helps maintain a consistent temperature before and after the basement is finished.
So what if there was a type of foundation that almost eliminates those issues? There is and they are called Insulated Concrete Forms, or ICF as we will refer to them frequently.
On a conventional foundation, you place one set of panels, get them leveled and stabilized, tie your rebar, and then put your other set of panels up. Stabilize everything together, brace it back, and pour your concrete in the middle. After the concrete has hardened, you pull off all of the bracing and forms, clean them off, and load them up for the next job. Of course, it's a little more complicated than that, but that's the basic process.
An ICF foundation follows the same principle - leveling and stabilizing, tying the rebar, bracing it all back, and pouring your walls. But they're easier to work with and one person can pretty much do 60% of the foundation by themselves because the forms are made of styrofoam and hard plastic.
The picture on the right is what a foundation looks like when it is ran about 3 rows up. A 9' foundation typically has 7 full rows.
Each wall block is 16" tall x 48" wide x 13.25" deep. Each block is identical to each other, as well. Corner blocks are the same but are in an L-shape. The best representation for how these blocks fasten together - Lego's.
To spare some details, you basically put these in place, make sure no seams line up with each other, clip them together, tie the rebar (which sits on the hard plastic "saddles"), put up the shoring system, brace it back, pour your walls, take off the shoring system, and you're done.
Below is a picture of the foundation ready to be poured on our New Raymer addition. The shoring system is installed every 6'-8' and is attached to the hard plastic saddles (pictured above) and then you can actually walk on this system, which makes working with the top of the wall exponentially easier.
The shoring system is the only thing that has to be disassembled after pouring the foundation. There are some smaller pieces of sheathing that have to be taken off from around the windows, common seams, etc. but the clean up time is probably a third of what it is on a conventional foundation.
The biggest misconception about the ICF foundations is that there is no concrete involved. Most of our customers hear about this for the first time and think that the foundation is only made of styrofoam.
But these foundations are the exact same as a conventional foundation, but with over 5" of insulation surrounding the walls. See the picture below showing a tape measure being held to the center portion of a block.
To clarify the 13.25" measurement stated earlier, the form starts with 2-5/8" of styrofoam insulation on one side, 8" of space for the wall to be poured into, and then the other side also has 2-5/8" insulation. The insulated sides provide an R-23+ value to the basement walls, which is significantly better than a bare concrete wall with the blanket insulation attached to it. Feel free to visit the manufacturer's website at www.foxblocks.com.
Cost
So, how do these forms fare in cost compared to a conventional foundation?
An ICF foundation is more expensive than a conventional foundation. There's not a significant difference, like double the cost, but they are usually about $4 more per square foot due to the cost of buying the blocks.
However, if you anticipate on finishing the basement in the future, we personally feel it's more beneficial to spend a little extra on the blocks. Why, though?
Per local fire codes, all exposed styrofoam has to be wrapped with drywall. This contributes to a decent portion of the extra cost. But the drywall is attached directly to the hard plastic saddles that you can see in the picture to the right. There is a saddle every 8" and the drywall can be screwed directly into it. So, the only framing in the basement would be interior walls for bedrooms, bathrooms, etc.
By choosing ICF, the customer is practically half way done with finishing the outer walls of the basement when the home is completed. We also usually ask our electrician to either install outlets per code, or at least get the wires ran for future outlets (if the customer desires to or can afford to). That way, when it's time to finish the basement, the contractor or homeowner doesn't have to remove any drywall to allow the electrician access to the styrofoam behind it.
In Conclusion
The bottom line with ICF foundations is, if the customer can afford the extra expense up front, we think it's the most economical decision in the long run. The basement will maintain temperature significantly better and the customer won't have to incur any extra expense to have every single outer wall framed and drywalled when it comes time to finish the basement.
Hope you enjoyed this little educational piece! If you still have questions/concerns or would like to see a foundation in person, please let us know and we would be more than happy to try and accommodate the best we can.
- C&B Construction
