Q. We are being told that our new front porch can be held up by fiberglass columns. This is confusing, because we wonder if they would be strong enough to hold up the roof. Is this a common thing to do? The contractor showed us pictures of different kinds of columns, including round and square with different styles, like Roman or plain, etc. What do you think of this idea? We expected wood columns that we could stain or paint.
A. So now I get to write a column about columns. Fiberglass can be molded to many shapes, including boat hulls, car bodies, I-beams and … columns. The material is synthetic, made of resins fused with glass fibers drawn from heated silica, which is basically fine sand, one of the most abundant materials on earth. One window company, Marvin Windows, uses fiberglass for their window frames because it is many times stronger than vinyl.
You could use wood for columns. It’s also one of the most abundant materials found on the planet, but the difference is that fiberglass, once heated, formed and cured, is completely stable and resistant to expansion, contraction, elongation, shrinkage, warping, twisting and rot. Fiberglass I-beams are the structural material of choice for buildings that house corrosive materials such as acids. A battery production facility would utilize fiberglass components, for example.
The one thing about fiberglass columns that I’m concerned about, from a structural design point of view, is the connections needed to other materials. Screws, nails, brackets and bolts may weaken the column unless reinforcement is designed and manufactured into it. Steel columns with steel connections are very strong and reliable, whereas metal to fiberglass, two dissimilar materials, may not be strong enough to resist horizontal forces. To be safe and redundant in the structural reinforcement, I often recommend that the fiberglass, which actually is capable of supporting many thousands of pounds of load, has a steel or wood column inside it, bolted into the foundation support system, to safeguard against the potential of being forced sideways by high winds, falling trees or vehicles.