Load Bearing Wall Identification
DEAR TIM: How can you identify a load bearing wall? I would like to knock down a wall between my kitchen and dining room that is just four feet long. To the best of my knowledge there are no electrical or plumbing lines in the wall. There is a phone line in this short wall. The wall does run perpendicular to the floor joists above and below the wall. What are my options? Tim G., Rochester, NY
DEAR TIM: Bearing walls have a mystic aura all their own. Plaster, drywall and wood paneling finishes that are applied to all interior and exterior walls act as a very effective camouflage in the average residential home. All walls tend to look the same. A cleverly placed bearing wall can be as dangerous as a stealth bomber. Remove one without adequate re-support and all sorts of things may drop down on you.
Keep in mind that bearing walls are ones that act as a structural element within a house or home. They typically are carrying and transferring a load from one point to another. In a properly designed home, the loads eventually get transmitted to a foundation, a thickened part of a slab and/or a concrete footer that supports a column or post. Knowing this, you can work up from these elements in the average home and locate many structural elements and bearing walls. But beware, some loads are very well hidden and not all bearing walls are found in the middle of a structure.
The exterior walls on houses that support the roof are primary bearing walls. Not all exterior walls are bearing walls though. There are many houses where just the front and back walls are bearing walls. My home is different. Because I have a hip roof that slopes towards each exterior wall, each of those walls is carrying some roof weight. To make it even more complicated, the second floor of my home has a smaller footprint than the first floor. Some first floor interior walls are actually supporting the main roof of my home. This innocent looking wall with two openings in it is a bearing wall that supports 20 percent of the roof and 33 percent of the second and third floor loads!
Frequently interior walls that run perpendicular to the run of the floor joists above and below are candidates for bearing walls. But there are many a wall such as this in a home that are not bearing any weight whatsoever. If you discover a wall or a beam directly below this wall or parallel with the wall within a short distance, then the suspect wall may be a bearing wall. Bearing walls are not always stacked one on top of another. This is why detection and identification is an exact science.
Don't assume for a moment that your short wall is free of electrical or plumbing lines. It is not uncommon for cables, wires and pipes to run horizontally from an adjacent wall to another wall as they run from one location to another. Trust me, as you begin to strip the drywall or plaster from this wall you could quickly run into a plumbing vent pipe or an electrical wire. I have on occasion discovered abandoned gas lines, heating ducts, return air ducts and even clothes chute pipes in very innocent looking walls. The absence of utility lines and pipes below a wall does not mean they are not present above.
Another surprise one can find in a wall is a column or post. The wall itself may not be a bearing wall but it is hiding a crucial support member. Several years ago I built a light commercial building that has a four inch steel column buried in an unsuspecting interior wall. From all outward appearances each and every interior wall in this building appears to be non-load bearing because the roof structure is all modern trusses. But this particular truss roof was different. It had a giant girder truss that was accepting loads from other trusses. This special truss needed extra support mid-span!
If you desire complete peace of mind, you should hire a professional to make the determination for you. Structural engineers are trained to do this. They are often listed in the Yellow Pages. Often you can get the advice you need for several hundred dollars. To keep the fee to the absolute minimum, remove the drywall or plaster from the wall before the engineer arrives. The fee you will pay will be very small compared to cost to repair structural damage that may result from a hasty demolition party.