Understanding Stair-Step Cracking and Its Structural Impact
Today we’re going to look at a few different buildings with header failure. One of these particular buildings is a brick facade and a brick header while the other building is also broke the side yet it has a stone header at the windows. Issues of header failure are significant and require significant structural repair, yet these areas of failure can actually be deterred or postponed or deferred for many decades if the building is just properly reported. Will explain this today and show several photographs of these issues from the field.
The problem with header failure is prolific, we see these issues throughout many historic buildings in Washington DC. Header failure happens when a door or window header cracks, begins to move, or breaks under the pressure of the load above. In most cases, door and window opening headers are actually carrying less weight than one might expect, but nonetheless, as the building shifts and particularly with cases of unmitigated masonry joint deterioration, these headers will become slightly dislodged and shift. In most cases header failure can be prevented by simply repointing or tuck pointing the masonry joints of the building in a proactive timetable.
The building shown in the picture below looks similar to many historic buildings here in Washington DC. This particular building was built just over about 100 years ago. At a glance, you can see that some updates and changes have been made to this facade. For example, the window at the top of the picture is in an opening with a recessed brick surrounding the window. That’s not original. It wasn’t built like that many years ago, at the time of the initial construction. Instead, somebody modified that window opening and replaced the original larger window with a smaller contemporary or more modern type of window and infilled the brick around the new smaller window.
This building was built with brick masonry in a common bond. Although the name for the common bond indicates that it’s prolific, it’s not as simple as the simpler running bond. A running bond just includes bricks set side-by-side in a stretcher course position where each brick’s middle is set below the end of the bricks below. By comparison, this brick configuration is similar, yet it also includes a header course interspersed at every 7th row. That header course provides more connection between the double wythe of brick work.
This type of strengthening bond helps prevent lateral deflection, yet the cracks you see here are largely related to lateral deflection in the facade. As we mentioned above, much of that lateral deflection could have been prevented by simply repointing or tuck pointing the facade in the decades past. As the more joints deteriorate, the cohesive nature of the brick assembly begins to lose connection and then the wall can start to waffle and fall apart. Lateral deflection can be described as a wall.or facade beginning to have a fattened belly. It starts to become a little bit round where before it was only perfectly flat.
In this case, the first place of acute problems happens to be at the headers of the doors and windows because that is one of the weakest spots where the brickwork is spanning an opening, yet it’s not just floating. There are multiple different types of headers, and this particular type of flat header is actually supported by a steel or wrought iron implement. In contemporary or modern times, masonry spanning an opening is often supported with a steel angle iron.
In the coming week, we will continue looking at similar types of window header failures, but particularly at a set of stone headers that are set within the brickwork, isolated and unique in nature among the entire facade of more typical bricks, and built in a radius turret facade.
We can Help
Our company focuses on historic restoration more than modern building upkeep, maintenance, and construction, but our company understands both types of construction very well and a full picture well-rounded approach is needed in any niche in the construction industry. Although we focus on historic restoration, repointing, tuckpointing and historic brick repair, our company also has technical knowledge and competencies in the areas of modern and contemporary construction as well as we become one of the leaders in that area of the market today. Understanding both historic and modern or contemporary construction is useful because both aspects help understand the challenges and potential solutions for challenges in building science and construction.
We can help with a variety of historic masonry restoration needs and upkeep, from modest tuckpointing and or repointing to complicated and extensive historic masonry restoration. Infinity Design Solutions is a historic restoration specialist contractor specializing in both historic masonry restoration such as tuckpointing our repointing, and brick repair. If you have questions about the architectural details or facade of your historic building in Washington DC, reach out and say hello and if we can help we’ll be glad to assist you. You can email us or call us on the telephone at the following link: contact us here.
