Structural steel is used to carry most of the weight of a building. Damaging the structural steel can cause the building to become structurally unsound and can increase the risk that the building will collapse. If you are performing renovation on a building and you do not want to cause damage to it, you will need to determine where the structural steel is located so you do not cause damage to your property.
Look at the Type of Home You Have
Exterior walls provide support for roof trusses. While gable-ended framing relies entirely on the exterior wall to support the home, hip roofs require more extensive support. Even with one story, the roof can weigh a considerable amount. Then, when there is even more than one story, the roof will need even more support. Look at the direction that the ridge runs. This direction is usually the same as the direction that the load-bearing walls will run.
Check the Basement
Another way to determine load bearing walls is to head to the basement and look for any walls that sit on the foundation. These walls would be considered the load-bearing walls.
Look for Beams
Buildings have beams that hold most of the home's load. They will either look like steel or will consist of concrete with steel in the center. The beams often provide support for multiple walls. The beams will usually not be visible except in rooms that are not completed.
In the center of the home, on the first and second floors, there are often walls that run parallel to the basement center beam. The walls on the first floor that run perpendicular to the floor joists are usually load-bearing walls.
Some walls end in posts or columns. These are usually load-bearing walls. The beams will often be incorporated into the wall. The wall might also have a boxy section that hides a beam.
Determine if You Have Steel Girders
Not all buildings rely on load-bearing walls. Some buildings have steel girders that transfer weight to the exterior walls. If these are used, there is a good chance that the interior walls are not load-bearing. Also, walls that do not have anything directly above them are less likely to be load-bearing walls.
When you are not sure if a wall is a load-bearing wall or not, you should consider contacting an engineer who works with structural steel, such as Garelick Steel. It might be possible to modify the wall, but you will need the appropriate bracing beforehand to prevent the building from collapsing.