Sound Smarter on the Jobsite: Bearing Walls

Everyone knows they're important, but what exactly are they? And can you tell if it's a bearing wall by knocking on it with your knuckles, ala HGTV stars and rookie realtors? (No!)

A "bearing wall" is simply a wall that carries load. The main job of structural components, be they beams, columns, walls, etc is to transfer the load of the structure (and whatever it's holding, like furniture and people) to the ground. These loads are called "gravity loads." There are other loads, broadly called lateral loads, like wind, seismic, etc that are resisted in other ways, like shear walls. But that's another thread. So bearing walls are important, and if you just take one out, the bldg is severely compromised and may even collapse.

How do you spot bearing walls? Well, in wood construction, joists (horizontal members that make up floors) can only span so far, but a house may be wider than that distance. So a bearing wall is usually somewhere in the middle, breaking the span of the joists. Here's what I mean, using a typical Boston triple decker as an example. This floorplan is repeated on each floor, and these were purpose built as 3 unit buildings. They are awesome! And they also happen to be very simple, structurally, which is why they were easy/cheap to build. Most were built in the 1890s-1920s.