Enhancing Structural Integrity with Flat Bar Reinforced Window Headers: Part II

This past week, we looked at some of the historic types of window openings and began comparing the wrought iron flat bar used at this particular historic building and the contemporary types of elements like shelf angles and structural steels.  Together, these elements improve the structural capacities of walls and building assemblies in construction. Because of the differences in tensile strength versus compressive strength and the integral nature of combining those elements to achieve a synergy in structural resistance, the advent of structural steel significantly changed building construction principles and techniques.

Wrought iron and steel have some distinct properties and historical usage in building construction. Wrought iron, used extensively in the 19th century, is a fibrous, malleable material with a low carbon content, making it somewhat resistant to corrosion.  It was

often used for decorative elements like railings and gates, and window grilles and door hardware in masonry buildings. 

Steel, on the other hand, has a higher carbon content and is stronger and more versatile than wrought iron, with superior load-bearing capabilities. However, steel was not widely available until after the Bessemer process was invented in the mid-19th century, which allowed for the mass production of steel by more efficiently removing impurities from iron.

Even with this advancement, steel did not become widely distributed and accessible for construction purposes until the late 19th and early 20th centuries.  Before this time, the use of steel in building construction was limited, and wrought iron remained the dominant material for window and door openings in masonry structures, like the historic row homes in Washington, D.C. As steel production ramped up in the early 20th century, it gradually replaced wrought iron in many structural applications, but it wasn’t yet commonly used in smaller residential buildings during the transitional period between the two centuries.

These details about the evolution of Steel and the transition from wrought iron to steel as a structural reinforcement in masonry, changed the methodologies used in masonry construction.  Particularly where steel is used as a masonry reinforcement and where used in window and door headers, steel changed the details of construction.   In the next picture below, you can see that the type of brickwork used in this portion of the building has changed from a running bond or common bond to a stronger English bond.

The English Bond Flemish Bond are commonly found here in Washington DC historic neighborhoods, but where the Flemish bond has a particularly charming visual aesthetic, the English Bond looks more monotonous and functional, yet has a significant overall strength capacity.

The picture below you can see that although the window header appears similar to a Jack arch, the underside of that header has a large radius. A large radius, in this case, happens to be a very shallow curvature.

Unlike some of the examples we looked at last week, at this particular header the bricks that comprise the jack arch looking header are set in a soldier course brick facing.

In the next picture below, you can clearly see there’s some deep recesses and what was originally built with a relatively close to flush joint in the brick mortar. This particular photo shows an example of where the mortar needs to be repointed. Although the building is an overall moderate to decent shape, as brick mortar deteriorates, without repointing, the building will deteriorate in a relatively non-linear timeline.  Once joint begins to deteriorate significantly as the mortar has here in the picture below, continuing deterioration happens at an increasing rate, without repointing and or tuck pointing.

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.