Learn everything you need to know about brick copings
Most historic buildings in urban areas have flat roofs. It’s possible to have a sloped roof on a brick historic building, in fact many slopes roof buildings are built with masonry but the majority of the brick buildings in the city have flat or low-slope roofs. There’s a few reasons why buildings were built like this, with low slope roofs, in historic times. Even in modern times the configuration of a typical building would warrant and justify a flat roof. The main reason for this type of configuration or physical layout is related to density and the proximity of buildings in urban areas like Washington DC.
Moderate to High-Slope Roofs
Moderate to high-slope roofs, also known as pitched roofs often require drainage at more than one side. (A shed-style type roof, with a moderate degree of grade but only a single plane of configuration, is one of the few exceptions.) In the city where buildings are built directly side-by-side, the shed style type of roof would be very similar to the existing roofs but with a higher degree of slope the parapet walls would have to be built taller than a flat or low sloped roof. This slopes roof configuration would require taller attic walls and larger attics which are somewhat unused or only partially used space. Also, the building code has limitations, depending on area and capacity in the overall height of the building so in effect the pitched roof would limit the height of the usable space of the building. The larger attic walls would require increased construction and materials costs because these walls are labor intensive to build, as they are not just partitions but also fire rated demising walls.
In effect, this type of layout and condition of building low slope roof buildings with parapet walls above the roof is extremely common in urban centers because, effectively, the building can get a much larger portion of usable floor and living space to the comparative cost of materials and labor involved in the requisite construction. However, this condition of side-by-side row buildings with parapet walls extending above the roof, while extremely common in urban neighborhoods, is almost exclusive or limited to just those urban areas and not commonly found in the countryside or suburbs, save warehouses and industrial parks as one of the rare exceptions.
The picture below shows an example of a parapet wall which extends above the framed portion of the building construction.
Why Roof Sharing Between Buildings Is Problematic
Brick demising walls most commonly, almost always, extend above the framed portion of the building structure. There are exceptions but where the parapet wall does not extend above the frame portion of the building, the roof then is shared between adjacent buildings and is actually a common element which is problematic because property lines divide the common element which requires coordination between multiple property owners at times of upkeep, maintenance, and repair. Technically, in the absence of a masonry parapet wall, there are also issues of potential lack or omission of a proper fire separation at the demising wall area. For example, in a building without a parapet that extends above the frame portion of the building a fire could easily spread from one building to another as the building may be separated by a masonry wall, bit if there is no masonry wall between the roof framing or roof decking at the top of the building the fire could easily jump from one building to the next.
The picture below shows a different angle of the same parapet wall from the photo above. You can see in this picture that the masonry wall, from the time of the original construction, has never been tuckpointed or repointed. This wall is built with a common brick. The common brick was installed quickly and sloppily. At this point, we recommend tuckpointing or repointing of that existing historic masonry and potentially more extensive repairs depending on the condition and / or any loose or disconnected brick that is still remaining in position but not currently adhered with a cohesive mortar joint.
The next picture below shows that same wall at a direct facing, at 90ﾟ from the wall. In this particular picture, you can more clearly see the voids and gaps in the mortar. As well, the motor has been applied, as shown below oozed out from the joints in the brickwork. That motor was never struck or smoothed with a trowel or jointer tool. We would recommend striking the mortar joints, at all types of reconstruction. Applying a proper strike to a mortar joint has several potential benefits. Generally the brick mortar striking process compresses the mortar to an extent which helps pack that mortar into the joint and create a more continuous fill of the joint, especially where it’s most important, at the outer edge of the brick wall. In historic brick masonry, as can be seen all around the historic areas of Washington DC, the mortar joints were often struck with a flush joint. The flush joint is relatively effective from a weather resistance perspective and the weathered joint strike is potentially even a bit better, but the overall positive effects of the weathered joint strike are debatable, because the reveal or recess between the top of the joint and the adjacent bottom brick edge is largely ineffective as a drip edge in most precipitation conditions. Either way though, leaving the mortar loose and sloppy as was done in the case of the wall below is a lower quality method of construction. However the reason that this wall was built in this fashion is likely because it was intended to be a blind facing where it would be against an adjacent wall with a covering such as a metal coping. At this point in time and likely for several decades past, no metal coping has been present above this wall and signs of deterioration are present.
The next picture below shows that same wall but from an angle looking downward. You can see the top of that wall and you can see the double whyte construction. This particular wall was built two bricks thick, in other words: double wythe, as is most commonly found in historic row building construction in Washington DC.
As precipitation, particularly in the form of rainwater, falls from the sky and lands directly on top of this wall, the water will pool, and infiltrate the masonry. The pooling of rainwater on suppressed or flat building areas is also referred to as “ponding”. As the rain lands on the top of that wall it will not shed or flow away from the wall because the top of the wall is built flat and without a grade or slope. Also, particularly between horizontally joined brick masonry units, as the mortar joints deteriorate in such an old historic construction like this, water will find its way through those joints. Historic mortor joints are semipermeable, even when almost brand new.
Brick Paving
Brick paving, in a horizontal type position on sidewalks and even on some roadways, is very similar but there’s a big difference. In this case as the mortar deteriorates, those bricks do not have a substrate layer below them to support the bricks other than the other bricks below in the building wall assembly which are also subject to deterioration from the same lack of defense from moisture at the top of the wall. Coping is needed to span and cover the top of this wall to protect this masonry.
Brick Demising
The picture below shows the top of a brick demising wall built in Capitol Hill in the mid 20th century. The top of the brick wall,built similar to other brick construction rowhomes in Washington DC, is capped with a terricotta coping. Sheet metals of varying substrate materials have been used as metal copings here in Washington DC, going back to the late 1800’s and it’s a little bit of an aberration to see a terracotta or stone coping on the top of a building facade or demising wall but in this particular case that waa the selection chosen and used. In the mid- 20th century that type of coping actually became more common for a brief period simultaneous to the advent of thin CMU block clad with brick at exterior facings.
The picture below shows an example of a very common type of metal coping on a rooftop parapet. You can compare this common modern method to the historic materials used. This metal coping spans the double whythe brick demising wall between two rowhomes.
Maintaining A Modern Flat Roof
To properly maintain, repair, and care for these historic buildings, a knowledge, interest and understanding of historic building principles is required. Here in Washington DC, historic masonry buildings are extremely expensive and the amount of financial loss caused by improper repointing and low quality construction is staggering. However, in addition to the direct financial value of the property, there is also a cultural loss when historic buildings are damaged. By comparison, consider neighboring poor cities, when historic buildings are damaged, it’s not just the loss of value to the property owner, there’s also a loss to all inhabitants and visitors of a city, present and future, who care about architecture, history, and culture.
We encourage all of our clients, and all readers of this article and to our blog in general, to prioritize the historic built environment of Washington DC and neighborhoods such as Capitol Hill, Dupont Circle, and Georgetown and become educated on on the difference between proper historic preservation versus improper work which leads to significant damage to the historic fabric of a building.
From a conservation and preservation perspective, several approaches can be taken to improve conditions related to deteriorated historic brick masonry. Primarily, lime mortar brick joints and low temperature fired soft red clay bricks should be inspected and checked on a routine maintenance schedule, either seasonally or at least annually. If brick masonry is kept in good condition, the life of embedded wood elements can be significantly extended. Hire a professional contractor which specializes, understands and appreciates historic construction elements and buildings.
In this article we talked about the terminology and concepts of historic masonry restoration, follow the links below for more related information from the IDS website:
- Binders in mortars and concrete
- Brick burns
- Butter joint
- Capillary action
- Cantilever
- Cementitious siding
- Cheek wall, masonry — Draft
- Chemical testing
- Code, building — Draft
- Cold joint
- Cold weather masonry work — Draft
- Damp proof course
- Downspout
- Electrical distribution panel — Draft
- Fenestration
- Ferrous metals
- Great Chicago Fire
- Green bricks
- Gutter, roof
- Lime mortar
- Lintel
- Load path
- Oriel window
- Oxidation
- Parapet coping
- Plug, clay
- Pressed bricks
- Raking, of mortar joints
- Raggle, aka reglet
- Rectilinear
- Roman bricks
- Roman arches
- Roof eave
- Roof termination
- Row buildings and row homes
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- Rubbed bricks
- Rubble stone masonry
- Sand, Builder’s
- Sedimentary rock
- Scratch coat
- Sprung arch
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- Squint bricks,
- Strike, or striking of mortar
- Tapestry bricks
- Tooth-in, interlocking masonry connections
- Vitreous
- Water diversion systems
- Zipper-joint
These concepts are part of the fundamentals of historic masonry restoration, tuckpointing, and brick repair.
The links in the list above will take you to other articles with more information on defects, failures, preservation and repair of historic masonry. You can learn a lot more on our blog. Feel free to check it out. If you have questions about the historic masonry of your building in Washington DC, contact us or fill out the webform below and drop us a line. We will be in touch if we can help.