Supporting the New Opening
When it comes to supporting the new opening, the default option is usually to use a steel beam. You could use exposed timber beams, although you will need more timber for the same span that steel can create. People often want to avoid timber posts in the layout, but they can be attractive features that also help subtly divide areas.
Understanding Span, Wood and Steel Beams
In Engineering terms, span is the distance between two intermediate supports for a structure. A span beam is what is required to replace an existing load bearing wall.
Wood, whether it’s dimensional lumber (whole wood) or engineered, usually costs less in terms of both the material and labor to install. Dimensional lumber beams, composed of several horizontally attached studs, can be built on-site, to save on supplier costs.
Laminated veneer lumber (LVL), composed of several layers of glued plywood comes pre-made from a factory but still costs less than structural steel I-beams. Also, attaching your other components to wood of either type is easy compared to steel. Steel needs fabricator-formed holes for bolts, which means careful architectural pre-planning.
Wood beams have their downside, though. Dimensional lumber shrinks as it dries. In fact, when the support beam shrinks, it pulls away from floor joists and can result in drywall stress fractures, floor squeaks and interior doors that fail to operate properly. While LVL avoids the shrinkage problem, it does cost more than beams of dimensional lumber.
Since steel is considerably heavier than any similar-sized wood product, the beams will require special handling with heavy equipment or a crane. These special handling procedures definitely add to the cost of the building. Typically, beam sizes are described in numeric form like 8×17. Usually this means the steel beam is very close to 8 inches tall and weighs 17 pounds per linear foot. This is a very common size found in many residential homes. That being said, you can get 8-inch-tall steel I-beams that weigh over 35 pounds per foot.
Steel beams grant you added design options that you just can’t get with wood. Because steel has much greater weight bearing strength, you can use fewer vertical supports for the same span and less height of the beam. Steel offers you larger uninterrupted open spaces. Plus, since steel beams come in a variety of strengths, you can easily work long cantilevers (overhanging roofs or floors with no end supports) into your design. No other material in use today can offer as many engineering options as steel.
One word of caution
Creating a new structural opening in a home is not a weekend warrior project. We recommend that you work with a structural engineer who will advise you on what best support beams should be used and what size to use.