Flat Bar Reinforced Window Headers: Structural Benefits
The history of masonry construction goes back thousands of years and is central to the evolution of the civilizations in human history. It wasn’t just a coincidental byproduct, it was core to the development of both civilizations and the growth of mankind, in terms of population and social complexities. In many ways, masonry is a simple but fundamental element in human history. You could even argue that the world we know today would be very different if it wasn’t for masonry construction.
Here on our blog and in on our website we’ve looked at several different types of historic arches used in masonry construction to allow for openings to be built for both windows and doors. These different types of arches have a history that goes back many hundreds of years, even thousands of years in some cases. Arches and headers allow for windows and doors to be installed in the middle of a structural load path without debilitating or limiting the strength of the load resistance to a significant extent.
Especially with the use of relatively small masonry units, for the construction of exterior facades, it is important to have relatively strong and stable headers or arches to support the load of the walls and the remainder of the load path above doors and windows. Without relatively strong headers or arches, the building load can crush doors and or windows and or at least lead to damage or further deterioration and to the debilitation of the building envelope over time.
The picture below shows a relatively typical historic brick wall, built on the exterior facade of a historic building, but unlike a typical historic segmented arch or jack arch window header, the ones shown here have a flat wrought iron structural steel support.
In the past, here on our blog, and here on our website, we’ve also looked at several different common types of historic brick arch headers. One of the strongest and earliest examples of a self-supporting arch in masonry was the Roman arch. The Roman arch looks like a semi circle arch because the top of it is rounded on a relatively short radius, not much wider than half the width of the opening.
It sounds like a relatively short radius would mean that the arch is less tall, but it’s actually the opposite, because with a short radius, an archway must be set close to the center of the circle that will be made by the arch. These arches do not have a bottom though because the bottom of the arch would occur into the opening space, the top is the only part that is actually incorporated into the opening.
Roman arches are actually one of the tallest of the types of arches, with the exception of some other notable types like the Gothic arch. The other main types of arches like the Jack arch, segmented Arch, and other common arches are actually not as tall as the Roman Arch and since the Roman Arch is much superior in a self-sustaining structural aspect, one of the few reasons the other arch types exist is because of the functional, non-decorative, purposes of being less tall. Being less tall allows a lower floor to ceiling height which basically saves costs and allows for cheaper construction with a similar ratio of fenestration or openings.
Unlike the common segmented window and door arches found in most of the historic parts of DC, these openings, shown here, have headers supported with a wrought iron flat bar. In many of the cases of historic arches, no steel or iron was used at all. In many cases at the time of original construction of these buildings, steel was not really widely available. Instead wrought iron was the predecessor and more common type of structural building metals.
In ancient historic times, prior to the advent of the Roman arch, often posting and beam type structural load paths were built to support buildings in areas around and above openings for doors and windows. Integral in-wall arch systems often perform much better than most post and beam type assemblies because posting and beam type assemblies alone generally lack some of the weather resistant characteristics of masonry facades. Also, wood elements, alone over time, set to span large openings in a horizontal position will generally deflect and sag.
The picture below shows one of these openings at a relatively low angle where you can see that the flat bar runs directly under the bricks of the header, but does not include a lateral and integral bend or angle as you would find in typical shelf angle or angle iron used in contemporary construction today.
In a follow-up article coming out soon, we’ll take another look at more angles and details related to this flat bar iron arch reinforcement. Some of the elements that we will look at are the differences between structural steel reinforcement and self-supporting and/or flat bar type reinforced openings and how the Advent of steel changed the types of construction used in contemporary building systems and how it evolved from its historic roots to the now common more modern elements.
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.
