Gothic arches in ashlar cut granite
Similar to one of the pictures that we looked at in this past week’s blog, in the picture below, you can see one example of the mortar joints, even more closely. The joints vary a little bit throughout all the different areas of the facade because they’re crafted by hand, but here, you can see a relatively continuous ribbon that runs in the middle of the mortar joint area. These ribbon joints are also sometimes referred to as strap joints, in some cases. (Technically though, there is a subtle difference between a strap joint and ribbon joint.
The strap joint can often, at least in the decades immediately following the initial construction, have a shaper edge.) Often in masonry construction, particularly in historic building facades, we find that several elements are intended to project away from the remainder of the face of the building to help with shedding water away from the remainder of the facade below.
The specific elements used may vary between architectural styles. These joints may help in that type of effort, to a degree, but one of the main benefits or aesthetic details of this type of application is that the ribbon joints, or strap joints, cast a thin but distinct shadow against the wall as the sun rises in the morning and sets in the afternoon. It creates a visually enhanced or contrasting characteristic across the face of the building facade.
The next picture below shows a Gothic arch, from a low angle looking upwards towards the top of the facade. Gothic arches are truly a beautiful architectural detail. After over 100 years of age and exposure to the elements, it still looks almost as good as it did the day it was built. In some ways the faint patina on the surface of the stones even improves the aesthetic. Of course, that’s up to an individual subjective judgment, but many people prefer the age historic look of these masonry facades.
If you look very closely at the underside of the keystone and voussoir stones, you can see the chisel marks left from shaping these stones. The keystone is the stone at the center top of the archway and essentially, from a structural perspective, locks all of the stone work together.
The keystone takes the load of the remainder of the facade stone above the opening and transfers the pressure of that load in a distributed application to the stones below. The voussoir stones, in turn, receive that load, or weight, or pressure, from above and then also transfer that pressure and weight both downward but also outward away from the opening of the window essentially resisting the force to collapse under the weight, into the opening area.
In this particular design and construction, the sides and top and bottom of the stones are cut with a rectilinear type form so that they can be joined and mate with the adjacent stones, but the vertical exposed face of the stones has almost a unformed type shape similar to a split face type masonry. Above, we mentioned the chisel marks left on the underside of the stones that you can see in the picture above.
The exposed vertical faces don’t show the same marks created during the chiseling and cutting and shaping of these stones. Here though the next picture below, you can see a clear example of this strap joint, or ribbon joint, of the motor. In last week’s article, we talked about the importance of proper repointing which applies to all types of historic masonry, in a relatively long timeline. We recommend having a mason, like our company who specializes in historic masonry, check on the building facade condition routinely.
In the case of historic masonry, that scheduled timeline may happen over a period of years. If a building hasn’t been checked in a long time though, it’s not a bad idea, and it can really help, just to have a mason like ourselves come out and look over the conditions of a 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.
