Wood is by far the cheapest and most abundant building material we have available. It’s also the easiest and most economic to work; ie, shape, cut, etc. With the advent of various types of structural composite lumber these days, wood has become even more affordable, stable, and with higher strength values.
Wood is also extremely user-friendly on the DIY level as well, and can be fastened or tapped into with ordinary, generic fasteners. From the building phase all the way to the living phase, wood is all-round easier to work, handle, and utilize.
And let’s not forget its positive insulative and acoustic properties. Wood has a significantly higher R-value when compared to steel, as well as a lower stiffness to density ratio, making it more insulated to sound travel.
Weaker in virtually every respect per unit volume when compared to steel. Wooden structures are somewhat limited in their design; in particular, long unsupported spans. Long wooden spans must have large cross-sections with a high second moment of area, rendering them impractical for most unsupported spans longer than about 2 to 4 meters.
Wood is also susceptible to termite infestation, and rot due to moisture or age. However, this can be avoided in most cases by properly treating and maintaining the wood, particularly the foundation beams and columns close to the ground level.
And as we all know, wood is highly combustible. A wooden structure is not one you’d want to be in during a fire event. There are precautions and ways in which to retard or slow fire down, but being that the primary bone-frame is highly combustible, there’s only so much you can do. Fire insurance premiums are therefore higher for wooden homes.
Although more expensive, both as a building product, as well as to install, steel is in most cases the preferred option if cost wasn’t a concern. It has an elastic modulus roughly 20 times higher than wood, allowing considerable freedom in the design and look of the structure.
For example, glass curtain walls, cantilevers, and large awnings are a few of the perks that are available with steel frames.
As far as insulative properties go, as mentioned above, steel is inferior to wood. However, I beams and C-shaped studs etc have, due to their shape, only the thickness of the steel that would act as a thermal and/or acoustic bridge. So if insulation is packed snug between columns, they can in some cases achieve an overall building R-value (not to be mistaken with material R-value) that is higher than a wooden structure.
Due to its high strength, steel also has the ability to support heavier cladding and floor slab materials, such as ALC and other cement based products. Granted, these heavier materials are more expensive, but they have high thermal mass and are extremely durable. In any case, steel frames provide this option.
Steel rusts. Yes, just as wood will rot, steel will rust if the conditions are right. That’s why steel must be properly galvanized and maintained if you want it to last.
Although steel structures are quoted as being strong in earthquakes, fires, and other natural disasters, in cases where a comparable wooden structure would fail, steel would almost certainly also bend and warp to the point the structure wouldn’t be safe or fit to live in. Such damaged steel structures cannot simply be bent back into shape, but must be torn down and rebuilt. The difference here is that a steel structure might last longer before completely collapsing.
The question then becomes, is the difference in price worth the simple fact that the structure would still be standing — albeit barely?
Being that the overall weight of the structure is fairly substantial, the foundation requirements are inevitably higher. Consequently, the foundation cost itself goes up as well.
In the end, the conclusion we seem to arrive at is that a steel frame seems to be superior in practically every way…if you can afford it.