Your chimney doesn’t hold your house up. I’m fact, when your house was built, a hole had to be built in the roof and floors because the chimney was in the way. The roof and floors are not held up by the chimney. You can remove your chimney, and your house will stand up just fine. You might just want to plug the hole though, so rain and birds don’t come inside:)
Brick is not a structural building material. Brick is merely a veneer. It’s a siding. The walls of your home or even high rise buildings are not held up by brick these days. Almost always, there’s a wood stud wall in brick homes that is the actual structure. Instead of nailing wood siding to that wall, brick was used. No different than wood siding being a nonstructural veneer, brick is the same. It’s just there to protect the real structure from the weather.
Brick facades are spaced about an inch away from the actual structural wall, so any moisture that makes its way through the brick has a way of draining down to the ground. This space is called a drain plane.” At the bottom of a brick wall, you will often see little tubes, screens, or gaps where any water that found its way through a brick wall to escape. These are called weep holes. Since you just learned a new word, here’s another brick-related word: wythe. A wythe is a stack of bricks forming a wall. It’s an old English word.
Back in medieval times, bricks did used to be structural, and a single wythe wall meant there was a single layer of brick between inside and outside. Since brick and the mortar that connects it is somewhat porous, a single wythe wall was not very luxurious. Water could deep through and there was no way to insulate it. The double-wythe wall meant there were two layers of brick with an air gap between. This gap provided a place for moisture to drain and likely not leak through the second, interior wall. It also provided a place for insulation.
Brick walls were structural when our limited engineering knowledge was as basic as: just stack things up and hope they stay. As buildings got higher, the bricks got bigger, and/or the walls got thicker to provide a more sturdy base. Think about it: the pyramids were built of giant stone blocks just stacked on top of one another. Gravity pulls down, so a massive brick base can resist that force.
Something that brick doesn’t support well is side-to-side motion from earthquakes and wind. When a brick building moves sideways, there’s nothing to stop the forces like the ground resists gravity. As brick moves sideways, they start to separate, and you can see this sort of structural failure when there’s a staggered separation in the mortar joints of bricks that sort of stair-steps its way across a building. This is sure-sign evidence of lateral failure (which means side-to-side movement).
To help to resist this sideways force, metal braces that look sort of ladders are laid horizontally in the mortar of brick to help to join several bricks together since they are all “glued” to the same metal “ladder.” This is known as: metal reinforcing. Before metal was readily used or available, a row of bricks would be oriented on end with their short side facing out, so they could span to connect each wythe of a double wythe wall. This was an early form of reinforcing. When you see a brick building that has a different orientation of bricks every ten courses (rows) or so, this is a sure bet that the building does NOT have metal reinforcing. You should stay away from these buildings during earthquakes.
When these sorts of buildings are remodeled, it is common that building departments will require the building to be “seismically braced.” This means a steel frame needs to be erected within the brick facade, so the steel does the job of holding up the brick (properly). Needless to say, adding steel frames within existing buildings is VERY expensive. Tearing the building down to rebuild would be much cheaper, but often, old brick buildings are preserved because they are deemed historically relevant. Consequently, owners of old brick buildings face really expensive retrofit costs if they ever want to remodel their building. These are often project stoppers. Even though everyone has good intentions when they want to historically preserve a brick building and make it more sturdy, the cost of doing so is rarely feasible for most people.
So, if you like brick, know that it’s just a facade in modern architecture. In historic architecture, it’s a beautiful burden because it’s not as strong as the three little pigs have made everyone to think. The flexible house of sticks would actually resist the forces of an earthquake quite well:)
If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help