Are you having trouble with your brick archway? You’re not alone. If your home was built in the last 30 years, chances are you fall into one of two groups: those with a cracked archway or those who soon will have a cracked archway.
While some masonry arches have a steel lintel under them, most do not since it is cumbersome and unsightly to bend and install a flat lintel under an archway. Most masonry archways, whether made of brick, stone, concrete, cast stone, or block, are designed to have their support installed internally because this is stronger and more attractive than having a visible lintel.
This internal support is commonly known as a bond beam. If you consider the visible design of an archway, like a brick archway at the front entrance of a residential home, you would see brick in the front, brick on the bottom, and brick again on the backside of the archway, making something similar to a U-shape. Although this example is referring to a brick archway, these practices can, however, be applied to any masonry archway.
On the inside of the archway is an open cavity that runs the length of the archway. This open space on the interior of the archway is the location of the bond beam. Think of this bond beam like a spinal cord on a human. When you see a ballet dancer arch her back, it’s the spinal cord that provides the support. Similarly, the bond beam is a skeleton of steel rebar strands arching through the open cavity within the archway and then along with brick ties placed in between the bricks, and extending into the cavity where they’re wrapped around the steel rebar strands. This connects the brick façade to the rebar, and then the cavity is poured solid with concrete. The concrete forms around the rebar and the brick ties.
Once hardened, the bond beam provides the support necessary to carry the load of the brick above but also forms a mechanical bond throughout the archway which makes it impossible for the brick in the archway to move out of its original position. Advantage Masonry installs a bond beam on every archway we construct in order to internally support and prevent movement of the brick.
In the last 30 years as inspections on residential homes decreased, so did the installation of critical components such as bond beams, brick ties, and moisture barriers. Unfortunately, most brick homes built within this time period do not have a bond beam. Therefore, as soon as the home experiences settlement of the foundation, the archway begins to pull apart. You might wonder how you can tell if your archway does NOT have a bond beam. It’s simple. If there is a fracture within the mortar, bricks, or both and it has formed a gap or misalignment, then you likely do not have a bond beam since a bond beam would prevent this type of movement. In this case, it would need attention. If left un-repaired, the archway would eventually collapse.
To build an archway, you first have to build what’s called a negative template. This is a wooden framework in the shape of the archway. It provides support for the masonry during construction and is left in place until the masonry has cured to a point where it’s capable of carrying its own load. You begin by laying the bottom ribbon of bricks right on top of the negative template. Once the bottom ribbon is in place, you build the front and back walls up, approximately 12-16 inches, installing the brick ties as you lay the brick. Then you install the steel rebar strands, wrap the brick ties around the rebar, pour the cavity with concrete, and let it cure overnight. The next day you can finish bricking up the wall on the front and back. Once the archway has sufficiently cured, you can now remove the negative template and your archway is complete.
The mortar cures 98 percent in approximately 28 days, and the remaining 2 percent cures indefinitely, making the archway stronger with time. If you suspect your home’s archway doesn’t have a bond beam, it’s beneficial to act quickly. If the problem is identified before the archway begins to move out of its original position, it’s sometimes possible to retrofit the existing archway with a bond beam. On the other hand, once the archway begins to move from its original position, the archway must be taken down and reconstructed because it would no longer be stable enough to repair in place.