The Purpose of Masonry Lintels
Where there are door window openings in the facade of a brick building, typical bricks above those openings are generally smaller than opening itself and therefore the brick needs structural support to span across the top of the openings to hold those bricks up in place.
Even though mortar and cementitious elements like concrete are strong, when mortar is built between individual masonry units, it lacks sufficient adherence and tensile strength to hold the whole brick assembly in place when it’s not supported from below. Lintles are one of the types of elements that span the entirety of the opening and beyond to support brick and masonry elements above. Today, we’re going to take a look at some examples of masonry lintels in historic facades.
These particular headers are cut in the shape of jack arches. Normally when headers are built with brick units in the shape of a jack arch, they have inherent structural stability, even with individualized brick units. The jack arches are almost flat, and as we explained, they still have a structural cohesiveness and resistance to vertical deflection because each of the voussoir bricks generally has a degree of angled taper.
Individual bricks, whether it be in a Roman arch or a jack arch, generally have a degree of taper created by rubbing those bricks, in historic processes. That tapered angle gives the brick the ability to lock together and form a resistive arch, even in the case of a jack arch header which is not actually arched. As a side note, sometimes these headers are still referred to as arches.
As you look closely at the underside of the lintels, you can see a horizontal relief cut into the underside of the headers. This particular relief allows any water that rolls back away from the front edge of the stone or cement lintel to fall off the underside of the lintel instead of continuing all the way back to the window. This helps preserve and extend the life of the window because with less exposure to water which runs down the face of the facade, the window is less exposed to the forces of deterioration and rot.
Often details like this are subtle, sometimes they’re hardly even noticeable. With a slight projection, in many types of different architectural facades, a masonry element that slightly projects beyond the planar face of the facade can prevent a lot of the typical non-wind-driven rain from hydrating the surface of the facade.
When buildings don’t take these type of passive typical weather pattern type effects into account, they unintentionally allow a greater degree of water to be in contact with the facade and therefore allow a greater degree of permeation into the historic masonry. Over time, obviously, a higher degree of hydration will result in accelerated deterioration of the historic masonry. As we’ve discussed often, here on our blog and website, these forces will result in deteriorated mortar, and in other cases will often also result in accelerated deterioration at the masonry units and or decorative elements of the facade.
The joints around the perimeter of the lintels also need to be checked and maintained from time to time. Although different from a typical brick unit, the lintel is also a masonry element that is surrounded and set in a mortar bedding at the angles of the polygonal shape. This header is shaped similar to a jack arch which, as we discussed above, isn’t actually in the geometric form of an arch. Nonetheless, either when built with brick, with voussoirs that are individually rubbed or cut to fit the interlocking shape, or set in an individual unit like this, the structure above the window or door openings can be properly supported.
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.
