The Strength of Steel

The Strongest Building Material
Pound for pound, steel is the strongest construction material available (unless you count exotic materials like titanium). It is so much stronger than wood that the two cannot be fairly compared. Indeed, steel has a strength-to-weight ratio 25 times greater than wood, which highlights the common misconception that a steel structure will be very heavy. Just the opposite is true. For a wooden frame to be as strong as a steel frame with the same dimensions, the wooden frame would have to weigh many times more, which is one of the reasons we don't build skyscrapers from wood. What is clear is that steel provides the greatest strength for the least weight and the greatest value for its cost.

Which frame would you rather be under . . .

. . . if a tree were to fall on it?

Tensile and Compressive Strength
Unlike wood and concrete, steel is extremely strong in both compression (resistance to pressing) and in tension (resistance to stretching). This is important because when something is bent it is compressed on the inside of the bend and stretched on the outside. A material that cannot resist both types of force is more prone to fail under a load. For example, concrete is strong in compression but weak under tension. That is why almost all concrete used in construction today is "reinforced" with steel rebar to add tensile strength. This combination of tensile and compressive strength gives steel such great resistance to high wind loads and roof loads (e.g. snow and ice).

On Easter Sunday in 1999, this Autumn
View model in Mendon, Louisiana
weathered a direct strike from a 150
mph tornado with no significant
damage.


During Hurricane Katrina, 140mph
sustained winds with gusts up to
185mph toppled six pine trees from
16" to 28" in diameter on top of the
roof of this Kodiak garage in
Abita Springs, Louisiana.


Although the falling trees damaged
some roof panels and underlying
purlins, the frame did not fail and
would have protected anyone inside
(note the crushed cars). The Augusta
model a few feet away suffered
almost no damage at all.


A charming Villager model Elasticity
The "elasticity" of a substance measures how far you can bend or deform it before it will not return to its original shape. Both wood and steel are fairly elastic, and this helps them resist loads without failing. Of course, steel can resist a much greater load than wood. As you probably know from experience, it takes a lot more force to bend a one-inch steel rod than it does a one-inch wooden dowell. Chances are, you can bend the wooden dowell to the point of failure and snap it, but what happens when the circus strongman bends a steel bar? It doesn't break.

Ductility
Even more important than being elastic, steel is extremely "ductile," which means that it can be deformed far beyond its elastic limit without failing (breaking). That's how we make the cold-formed components for your home. We deform steel into the shapes we want. This quality is very important in the most extreme circumstances like earthquakes and hurricanes. Even if you were hit with a quake so violent that it permanently deformed your steel frame, the steel would continue to support a load until it completely failed, which could keep your house from collapsing and give your family time to escape. Wood, on the other hand, is not a ductile material. When stressed beyond its elastic limit, wood fails almost immediately. In a wood-framed structure, almost all the ductility is in the connections — the steel nails and fasteners that hold it together. That is why a steel-framed home is much safer in an earthquake. It can absorb far more force before it begins deforming, and it can continue protecting you long after that point is reached (see pictures at right for a real-world example).

Fire Resistance
Steel's resistance to fire is well known, but we cannot emphasize it too strongly. While the chances of facing a hurricane or earthquake are low in much of the country, every homeowner must guard against the threat of fire. A Kodiak Steel Homes framing system will help you do this because it will not contribute to a fire. Although given enough time and fuel virtually any home can burn, if you avoid using other flammable materials on your roof and in your walls you can greatly lower your risks.

Termites, Mold, and Rot
While not as sensational as the natural disasters described above, problems like termites and mold cause billions of dollars in damage to wood-framed houses each year, threatening people's health and financial security. Simply put, steel eliminates these threats. As long as you do not use other materials that are at risk, you can forget about them. Steel also does not shrink, swell, warp, or settle, nor does it weaken over time under a load as wood does ("metal fatigue" is caused by repeated bending or twisting and not the steady or repeated application of force).

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