Between late-night marathons at the CAD station…
… early morning conferences with building families, and then late afternoons (after it either cools off or STOPS raining) loading trucks with hay destined to families in Colorado who are getting their butts kicked by the fires and drought… as well as greedy hay brokers capitalizing on shortages to make quick cash at already suffering families expense. …
(Hay has doubled in price in CO due to this greed. It’s just unconscionable. Hay brokers make Ronin cuss like a sailor.)
We’re up to our armpits in work.
So, guess what time it is?
That’s right… say it with me… MAIL BAG TIME!
We hear you go on and on about how steel beats wood. (Around here, it’s a “Rock, Paper, Scissors, SPOCK” thing every time it comes up.) :)
But the guy down the street (he’s a contractor) is telling us that a wood wall will meet or exceed a steel wall for relative R values, every time.
It’s HIS position that we should just use our money to build a stick home;
“…like everyone else. If steel homes are so good, why aren’t they on every block?”
We’re at a loss to dispute this. Can you?
Confuzed in Mayberry…
(First, kudos on your “Big Bang Theory” insider joke. We love that show…)
Contractors build what contractors KNOW.
However, in this case, your contractor doesn’t know much about US or ISBUs.
We’ll address the last point first…
The REASON that ISBU homes aren’t embraced in the US is threefold;
- The lumber industry has made a killing selling material into the construction market for decades. This profit has bought and paid for politicians to increase the strength of their lobbies and stranglehold on construction in general. Material shortages due to increased moratoriums on cutting timber have only made that worse.
- Steel home construction takes a different skillset than that typical of the standard single family tract home. It means specialized crews with specialized skills. Wood builds MOST homes in the US. Fewer Steel crews exist, so they naturally cost more to hire as subs.
- ISBU homes have suffered here from a lot of negative press and media coverage. Globally, ISBU homes thrive. They thrive because they WORK. In America, they’re seen as “different” and as such, it’s harder to embrace something “unknown”. We’re behind. Period.
It’s generally hard to understand something “new”. And while ISBU housing isn’t “new” beyond our borders, here in the US (as a nation)… we’re still struggling to embrace them. The media and it’s apocalyptic portrayal of ISBUs isn’t exactly helping… except maybe in California! LOL! It leads to fear and some required “new investment” (like at the local planning and zoning office where they have to learn a new product before they can “approve” it) and as such, the learning curve slows down the entire affordable housing process.
Rest assured that as time goes on, ISBU home builds will escalate. As more and more documentation (in AMERICA) is compiled PROVING their value to AMERICAN families, the stigma will be forced back into the shadows, where it will still be fervently and passionately harbored by those “not in my backyard” types…
However… at some turning point, the numbers will prevail as we PROVE to the masses what we already KNOW.
Yes… many of us already know what ISBUs and Corten Steel bring to the table. So, we’re on the leading edge of that “housing” curve. As such, we’re forced to pave the road for those who will follow.
After all, it’s easy to become a disciple when someone else does all the hard work to prove the path was safe, sustainable and even affordable, right? ;)
That said, let’s talk about wall construction;
When you’re talking about exterior wall “performance”, you’re usually talking about “Thermal Bridging”.
“Thermal Bridging” is the transference of temperature (hot OR cold) through the materials you use to actually frame your exterior walls. It’s just basic conductivity.
MOST typical exterior walls are framed using wood studs (2x4s, 2x6s, etc…) place 16″ OC, that is… 16″ apart, running vertical – spaced “on center”. Top and bottom plates tie it all together in a big wood skeleton with “cavities” in between each stud. This cavity is used to hold your insulation, be it fiberglass, cellulose or foam (be it rigid or sprayed in).
Typically, this insulation is either fiberglass batts or blown-in cellulose.
Combining your R value of the wall itself, plus the value of the insulation you add… and then subtracting the openings for doors and glazing will give you a “relative R value for the wall”.
Wood studs have an “R value” of about 1.
But… wood walls are about three times as conductive as the insulation (usually rated at about R3 per inch) that you stuffed into the cavities.
You can see where I’m going with this.
You’re adding insulation to the wall, but some of it’s value is being lost to the wall that contains it.
Basically, you have to take into consideration the “Thermal Bridging” losses created by the structural components of the wall itself.
This means that at every stud location in your wall, you’re leaching a significant amount of heat or cooling during the course of a typical day or night.
This is “Thermal Bridging” at work.
When we calculate R values in wood exterior walls to define a wall’s performance, we usually subtract approx. 10%, to account for this heating/cooling loss.
That means that we have to build thicker walls to get the performance required in some regions. This added lumber and insulation costs you more and that increases the price of your home production.
As you can see, wood walls aren’t exactly “Performance Princesses”.
With ISBU walls;
(Oh, quit it… You can stop groaning. you know where I’m going to take this already.) :)
First, you don’t BUILD them. They come “ready made”. All you do is modify them for your openings (doors and windows).
We design and even (gasp!) build ISBU homes with the insulation on the OUTSIDE of the home.
The OUTSIDE? What?
Yes. Why in the world would you make a small framing system SMALLER? Most of our homes are based on the premise that we are squeezing every single square foot out of them that we possibly can.
After all, you’re paying for that square footage, You should be using it. ALL of it.
And, we do it using the existing steel structure of all that wonderful Corten Steel combined with SPF (and I’m not talking about sunscreen, smarty-pants).
SPF – Spray Foam Insulation (closed cell, please)
… allows you to encapsulate the entire home in a monolithic coating of dense, luxurious, non-decay-able insulation that stops thermal bridging in it’s tracks.
You’re basically covering the area below the floors and the outside of the exterior walls with an insulation product that yields R7 per inch. This means you have “thinner walls” because your insulation performs better.
Beyond that, I don’t need to use a separate moisture or vapor barrier, because SPF provides both of those as a by-product.
Additionally, all that foam creates a cocoon of foam that even lends itself to increased structural integrity. You’re basically gluing all your components together using that foam as a binder. It’s like duct tape on Mark Martin’s NASCAR Race Car! :)
Once you’ve applied the foam (we’ve talked about how to do that in several places on this blog) you cover it up with your favorite exterior veneer or cladding product.
NO THERMAL BRIDGING.
And, covering it all up is easy. Around here, we like Hardie Plank. Cement board based products are easily applied, very durable (they are extremely weather resistant in comparison to some other materials), low maintenance and relatively inexpensive. That’s all good.
Some families like rock, stucco or even brick. Your ISBU home is based on steel BOXES. You can make it look like whatever you want. The limit is your creativity.
Is this process a bit more expensive than the traditional stick build your contractor was trying to sell you? Yes.
However, it’s stronger, more efficient, and in most cases, almost maintenance free.
Here’s something else to consider;
ISBU homes are also easily secured. This makes them ideal for remote or rural locations like off-grid or vacation homes.
Building an ISBU STEEL home means that nobody gets in unless you invite them in. Secured ISBU Homes require torches or grinders to gain entry. :)
Your neighbors are probably getting energy audits and adding insulation and caulking as the existing insulation and “seams” in their homes break down and lose their “R value”.
With a properly constructed ISBU home… YOU won’t be doing that. Ever.