Open Floor Plans

Most new home constructions since the early 1990s have featured open floor plans that eliminate some partitioning walls from rooms that were once kept separate in traditional home architecture.  Simply put, a home that has no partitioning wall between kitchen and dining room, dining room and living room, or among all three is generally considered to have an open floor plan. In older homes, a parlour, living room, den, dining room, kitchen, even a butler’s pantry or a breakfast nook – all the shared spaces in the home – were kept separate by interior walls.

What are the benefits of an open floor plan?

For starters, a home with a large and open interior space can feel like it’s much larger than it actually is. Incorporating the meal prep area, the dining area, and the lounging or living area all into one big space can also bring your family together more often, even if they are engaged in separate activities.

Perhaps the greatest advantage of an open floor plan is that it eliminates or incorporates underused spaces (parlor, formal dining room) into the spaces that tend to get the most use (kitchen, living room).

Opening up an older home

It’s important to consider the structural implications. Be aware that it’s not always obvious whether a wall has a structural function.  Even lightweight timber partitions may be providing support or stability.

Not all homes are well-suited for open concept floor plans in their natural state. In fact, many require the installation of steel beams to bolster their structure and allow for the removal of one or more load-bearing walls.

To determine if your home can accommodate this layout, you will likely need to work with a talented structural engineer. They will assess the structure of your home and compare it to your desired layout to let you know how to make key improvements.

open floor plan

Load Bearing Walls

A bearing wall is a support wall that transfers load from above down through the structure to another wall, a beam, and/or a foundation.  Needless to say, all exterior walls are load bearing.

The bigger a house is, the farther apart its load bearing exterior walls will be and, thus, the more load bearing internal walls there will need to be to support the floor. Often, these load bearing walls are roughly near the center of the house because the center of the house is the farthest point from any of the exterior walls. Look for an internal wall that’s near the relative center of your house. There’s a good chance this wall is load bearing, especially if it runs parallel to a central basement support beam.

load bearing wall

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.

steel beam spans
wood truss table
header span