This week we picking up and covering the second part of a discussion looking closely at case studies and the principles of masonry foundation decay and deterioration in the presence of excess moisture. The outline for last week’s and this week’s articles follows below, this week we will cover sections IV through V:
We happen to think this week’s discussion is particularly interesting. In the past we’ve discussed the litany of environmental impacts on historic brick buildings, especially in terms of degradation and deterioration, and we’ve also touched on the issues of climate change. However, in this week’s article we talk much more about the areas of ensuing and amplified environmental driven deterioration. This topic is particularly interesting because it’s not something DC and Capitol Hill residents have had to really deal with in the past, but this issue will be an increasing concern in the future. Restoration and overhaul of historic masonryRestoration and overhaul of historic masonry, a complicated and laborious process, is currently extensively needed within Washington DC’s historic neighborhoods like Capitol Hill. As these historic brick rowhomes bear the marks of time and associated deterioration, weathering and wear, a comprehensive restoration process becomes necessary from both a structural and aesthetic perspective. Historic masonry restoration involves a nuanced process of rejuvenating old buildings, particularly their brick and mortar components, in an attempt to preserve their original character. The lion’s share of historic basement restoration in Washington DC involves some degree of repointing and tuckpointing, which entails repairing the joints between bricks. Historically compatible mortars are used, some with a higher lime content for increased flexibility and breathability, and others with lower lime content for reduced compressive strength. It’s not intuitive, especially in the American culture, to selectively choose a building material because it has a lower strength, but the reality is that historic bricks were fired at a relatively low temperature, especially when compared to modern bricks fired by combustion fuels. Since historic bricks were fired at lower temperatures, they have a much lower compressive strength and for the mortar to be compatible, particularly with common brick as opposed to pressed brick, the mortar must actually have a lower compressive strength. The brick composition varies between buildings and even areas within single historic buildings, two categories are found in most often: bricks at the sides and rear of structures are generally common bricks. These bricks were kiln-fired at lower temperatures, resulting in reduced strength but higher absorbency. At some buildings front facades, brick with higher consistency of constituent materials and shape / size, compared to other bricks in a building assembly are referred to as a pressed bricks. Normally pressed bricks will have a very thin motor joint, often referred to as a butter joint. During restoration, the old mortar between the bricks is tediously removed and replaced with fresh mortar that closely physically mirrors the original but has increased homogeneity. Compatibility and breathability with the existing bricks are prioritized to maintain the building’s historic physical properties. In essence, historic masonry restoration is akin to providing a thorough makeover for aged structures, focusing particularly on their brick ajd mortar components. Through tedious repointing and strategic brick replacement, a building can rejuvenated while adhering to its original design and ensuring its structural durability. Bricks used at the below grade foundation portion of the building were generally common bricks, even though common brick has a lower compressive strength resistance, it was still strong enough for the foundation of these historic buildings. It’s actually very rare for a pressed brick to be used at any location in a building except where it’s visually observable from a public area, and generally only where visually observable at the front facade. So, in this case where a common brick is used at a foundation, almost in all cases, that common brick will also be set in a common mortar joint. Common mortar joints included less binder material, essentially, less lime in mortar mix ratio. Effectively, with a common brick joint at a below grade brick assembly, the walls were generally somewhat porous, especially after decades of aging and deterioration. ![]() We looked at another, similiar. picture from this particular building’s basement in the last article. A sump pump has been installed and there are also separate perforated gravity drains as well. Without the waterproofing, even after tuckpointing the brick would still deteriorate at an accelerated rate. The connection between building deterioration and climate change.In all of our discussions on deterioration and entropy in systems related to masonry and really any part of the overall building, there is a recurring underlying theme. All of the forces of deterioration and eventual destruction of buildings are related to nature. The environment outside, essentially everything out there outdoors, is changing. Climate change is real, despite the politicians and supposed pundits on the right and the conspiracy theorists who believe that climate change is a hoax. It’s actually happening and more and more we will continue to feel the effects of climate change, all around us including right here in our lives where climate change accelerates and exacerbates the elements of nature which lead to masonry deterioration. There’s been pretty strong evidence of climate change, destruction of our environment by proliferation of unregulated chemicals and manufacturing, the greenhouse effect, and acid rain, since the 1970s. However concern for the environment has constantly been derided, considered the passion of quacks, to hug a tree and save the planet. Just four years ago, the president of the United States ridiculed and told Greta Thurnberg, a child at the time, to “chill out’ because she cared about climate change. Meanwhile, while the people in power create a smokescreen, destruction to our environment is happening at an alarming rate and we will pay real consequences. We generally think about those consequences in more abstract terms, such as the idea that we’ll be a little less comfortable in the summer and have storms that are a bit more extreme, forcing us to pay higher insurance premiums and deductibles as the insurance industry continues to profit, even under the strain of increased costs related to storm damage. ![]() This picture shows a modern construction, with CMU aka cinder block, in Capitol. The building was recently converted into a condo building. The single wythe cinder block always leaked, during the approximately 7 year life of the building, since there was no waterproofing at the exterior or foundation of the building. These pressures will significantly increase with continued global warming, past a point of ecological destabilization. As the environment continues to destabilize, weather will become more extreme which will lead to the continuation of the deterioration if historic buildings, especially like those in Capitol Hill and the historic neighborhoods of Washington, DC. There is an interconnection between climate change and the condition of our historic buildings in Washington DC. Weather is simply one of the main drivers of deterioration. As weather becomes more extreme, with more precipitation or specifically precipitation thatless predictable or in greater force overall, there will be a corresponding negative effect to the condition and aging or deterioration process of historic masonry. Climate change ushers in a series of environmental shifts, cascading together, including increased rainfall, more frequent and intense storms, and fluctuations in humidity levels. These changes impact the moisture dynamics of masonry structures. As rainwater infiltrates the porous masonry, the freeze-thaw cycles become more pronounced due to temperature fluctuations. This repeated expansion and contraction stress leads to the gradual deterioration of bricks and mortar joints. The increased moisture levels also provide an ideal breeding ground for biological growth such as mold, mildew, and general bioconalization further accelerating masonry decay. The effects of climate change are not limited to moisture intrusion alone. Rising temperatures and increased humidity levels contribute to a phenomenon known as salt weathering. As rainwater infiltrates the masonry, it dissolves soluble salts present in the materials. Upon evaporation, these salts crystallize, exerting pressure on the masonry and causing surface spalling and efflorescence. Additionally, the intensity of solar radiation can lead to color fading and surface degradation of historic materials, altering the visual character of the buildings. The foundation, a critical component of any structure, is particularly susceptible to the impacts of climate change. Increased rainfall and groundwater levels elevate hydrostatic pressure against the foundation walls. This heightened pressure can lead to seepage and water intrusion through cracks and imperfections in the foundation, causing moisture-related issues within the building. As a result, foundation stability may be compromised, necessitating comprehensive repairs and reinforcement to mitigate the risks of structural damage. ![]() When you think of foundations, cement, and mortar, you don’t really think about the interior type of materials which are extremely susceptible to exposure to moisture. This basement, at the time of original construction was unfinished, and stayed that way for over 100 years until the basement was recently underpinned and a new wall layout was built to create an interior living space. In coming decades, there will be an increase in the trend to use every available square foot off an interior space as property prices increase, not just in dollar for dollar terms but also in terms of a proportion of CPI. In the face of these challenges, the preservation and maintenance of historic masonry buildings will eventually evolve to incorporate adaptive strategies that align with the realities of a changing climate. Sustainable preservation practices, such as the application of modern breathable waterproofing systems and protective coatings, offer a means to mitigate certain types of moisture intrusion while allowing trapped moisture to escape. These systems might be able to function like a shield against some of the impacts of climate change, safeguarding the masonry from degradation to an extent. As the long term impacts of climate change become increasingly palpable, holistic approaches to preservation may slowly emerge. Historic masonry buildings, in time, may be viewed through a lens that recognizes their vulnerability to the changing environment. Preservation strategies that encompass comprehensive site analysis, ongoing monitoring, and adaptive management are potentially useful. As Capitol Hill’s historic brick rowhomes weather the dual forces of time and environmental shifts, the combination of sustainable preservation practices, adaptive restoration strategies, and a respect for architectural heritage becomes more important. At the time of publishing this article (late August of 2023) the National Trust for Historic Preservation highlights the issue of climate change and the associated damage to historic American architectural treasures, right on their home page. ![]() The architectural floor plan above, courtesy of the Library of Congress, under a creative commons license, shows the wall layout of the Decatur House in Washington DC, the current home of the National Trust for Historic Preservation. In a future article we look even more closely at the future potential impacts of climate change on out historic brick and mortar buildings of Washington, DC. Climate change poses a range of threats to the physical structures of historic brick buildings in Washington DC. More intense and frequent weather events, such as heavy rainfall and extreme temperatures, can increase moisture exposure and water intrusion, weakening mortar and bricks. Freeze-thaw cycles, salt damage, mold growth, and shifts in vegetation and pests can further accelerate deterioration. Erosion, foundation instability, rising labor and material costs, as well as potential regulatory changes, compound the challenges. The new threat of climate change basically amplifies all past threats and concerns and elements of building deterioration from natural or environmental sources. 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. 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, fill out the webform below and drop us a line. We will be in touch if we can help. <p>The post Deterioration of Masonry Foundations In The Presence of Moisture – Part II first appeared on Infinity Design Solutions.</p> Via https://www.ids-dmv.com/masonry/deterioration-of-masonry-foundations-in-the-presence-of-moisture-part-ii/
0 Comments
Leave a Reply. |
About UsInfinity Design Solutions LLC (IDS) is a full service general contracting company in the heart of the Dupont Circle neighborhood of Washington, DC. We focus on repair and renovation of buildings and facilities in both historic designated neighborhoods and the commercial-zoned central business district of the city. Follow Us
|