Q&A / 

Residential Steel Beams

DEAR TIM: My house plan calls for steel beams that will support the floor joists and even parts of a brick wall. Can I substitute wood beams for steel? Is a steel I beam hard to handle on the jobsite? Do you think I can install one with some friends? How can you get the best steel beam prices as my budget is pretty tight? If I find a used steel beam, do you see any problems incorporating that into my new home? Steve B., Cinnaminson, NJ

DEAR STEVE: Steel I beams are pretty husky structural components used sparingly on a residential building site, because wood is the primary structural material found in most homes. However, steel is a ho-hum material on a commercial or industrial construction project as it’s the mainstay of these larger projects where wood is scorned because of its inherent fire danger and limited characteristics as buildings get big.

This custom home had multiple steel beams that intersected at 90-degree angles. Note how tall the beams are. PHOTO CREDIT: Tim Carter

This custom home had multiple steel beams that intersected at 90-degree angles. Note how tall the beams are. PHOTO CREDIT: Tim Carter

Architects and engineers employ steel beam design in homes for both beams and columns because it’s so strong. You can typically hold up the same loads with wood, but you need more of it and usually the size of a wood beam is much larger than a steel I beam, that’s holding up the same amount of weight. Termites and other wood-destroying insects don’t eat steel, so that’s a distinct advantage if you want certain parts of your home to remain standing.

You can substitute, in many cases, a wood beam for a structural steel beam. If you desire to do this, be sure you have a structural engineer, or an architect, specify the material and the needed supports. If you do use steel, pay close attention to the connection details at the steel beam support. The connections between the beam and columns must be secure.

I would never install masonry on a wood beam. There is too great a chance the wood will deflect and cause failures in the masonry. What’s more, it may be a building-code violation in your area.

Steel beams, as you might suspect, are heavy. Steel beam dimensions and sizes are not the same. You can have two different beams that are nearly identical in height and length, but one may weigh twice as much as the other beam. Typically, you’ll see beam sizes called out in numeric form like 8x17. Usually this means the steel beam is very close to 8 inches tall and weighs 17 pounds per lineal foot. This is a very common size found in many residential homes. But you can get 8-inch tall steel I beams that weigh over 35 pounds per foot. I installed 10x31 beams in the last house I built for myself.

But take a moment and do the math. Let’s say you have a ranch home and a 40-foot-long 8x17 beam is called for in the plans. You can have that beam delivered to your building site. Don’t try lifting it yourself, as it weighs almost 700 pounds. A smaller beam that long presents handling challenges as well because it will be like a wet piece of spaghetti when you pick it up with all your friends. If you’ve never handled beams before, it’s best to work with smaller ones before trying to handle long pieces of steel.

Steel is a commodity, and its price fluctuates. The current steel beam price you have to pay for new steel may not be bad as you might think. Currently, the market is depressed and supply may be far greater than demand. You may be pleasantly surprised to discover that you can purchase a construction steel beam for not much money.

You may be able to find decent steel beams from a demolition contractor who routinely salvages them from buildings. They sell them for scrap, so the price you pay will usually be much less than that of a new beam. However, you have all sorts of challenges when dealing with used beams. You might not get the exact size you need, the beams can be bent and you have to figure out how to transport it to your job site. My guess is a demolition contractor is not set up to do this for you. But stranger things have happened.

At the end of the day when you compare all the costs involved in obtaining a used beam instead of a new one, you may discover there’s not that much of a difference in price. In any event, be sure the beams you use are primed and painted to prevent or minimize rust.

If you decide to try to erect the steel yourself on a job site, be very aware of the dangers. The pockets in a poured concrete foundation are not that deep and if you’re not careful the beam can slide out of one end while you’re futzing with the other end of the beam.

To level beams in pockets you need solid-steel shims of different thicknesses. Never use wood shims, even treated lumber that is not supposed to rot. The heavy loads on the beam can compress the wood over time.

Steel beams can be blown over by wind if they are not secured. I’ve seen beams collapse after a rainstorm saturated clay soil causing it to expand and lift up columns that are supporting the beams. Hundreds of pounds of weight floating above your head and body on a construction site are never to be underestimated.

Author's Notes

I received the following email from James Calhoun, who is an Architect. He wrote:

"Tim, something you might want to know. Most municipality building codes do now allow used structural elements, like old steel beams, to be placed into new constructions without certifications by an Architect or Engineer (who in their right mind would do that...) or a serious (50%) devaluation of the rated structural capability of the member. Otherwise, you did a good piece on the advantages of steel in residential structures. I design steel for homes all the time."

Thanks, James.

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