Terra Cotta Facades: Assessment and Restoration – 2015

Erik Valentino, Masonry Preservation Services, Inc. (MPS)

This year, Erik Valentino continues his participation in the AE 537 (Building Performance Failures and Forensic Techniques) visiting practitioner lecture series with an encore  presentation titled “Terra Cotta Facades – Assessment & Restoration”

Mr. Valentino’s has presented several masonry related topics to the class over the years.  You can view the summary, reference material and discussion of one of his previous historic masonry presentations by going to the Building Failures Forum post: Historic Mass Masonry Restoration. You can also find some good tips on all forms of masonry restoration including brick, stone and terra cotta (the subject of this post and discussion) by visiting the Masonry Restoration page on the MPS website.

As noted in the National Park Service Preservation Brief 7 summary (see below for link to full brief): “Today, many of this country’s buildings are constructed of glazed architectural terra-cotta. However, many of these are in a state of serious deterioration and decay. Glazed architectural terra-cotta was, in many ways, the “wonder” material of the American building industry in the late 19th century and during the first decades of the 20th century. New technology and methods of rehabilitation now hold promise for the restoration and rehabilitation of these invaluable and significant resources. Restoration/rehabilitation work on glazed architectural terra-cotta is demanding and will not tolerate halfway measures. Today’s preservation work should equal the spirit, attention to detail, pride in workmanship and care which characterized the craftsmanship associated with this widely used, historic masonry material.”

Unfortunately there are fewer craftsmen with the skills to repair and restore terra cotta than ever before. In addition, many architects and engineers are not familiar the performance and special techniques needed to investigate and execute terra cotta restoration projects. A good start in educating yourself on the topic (especially if you were not fortunate enough to have attended Mr. Valentino’s seminar) is to read and study Preservation Brief 7 (provided below) and enter into the discussion that follows at the bottom of this post.

For more detailed information and extensive references on architectural terra cotta:Download the Bibliography of Architectural Terra Cotta

Additional reading on the topic of Terra Cotta preservation and restoration can be found by using the link provided below to Preservation Brief 7

Preservation Brief 7

The Preservation of
Historic Glazed Architectural Terra-Cotta

National Park Service

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46 Responses to “Terra Cotta Facades: Assessment and Restoration – 2015”

  1. philr
    October 25, 2016 at 8:04 pm #

    One original concern that I saw with terra cotta, is the fact that damaged units have to be replaced with original materials, to match correctly However, after I though a bit more about it, it may be easier than matching a certain tint of old brick or a mortar color. Custom terra cotta replacement units can likely be “experimented with” in a much more economical way, in smaller quantities, than a palette of brick.

  2. YusufA
    October 25, 2016 at 1:29 am #

    Nice blog there Yingze. It is good to see how beautiful the modern use of Terra-cotta is in building facades. I was wondering on how sustainable the material is and I came across this site which discusses that.

    http://www.inmatteria.com/2015/12/26/the-use-of-terra-cotta-cladding-and-its-remarkable-sustainable-results/

    Here, the conventional ceramic production is compared to that of Terra-Cotta and goven that the latter is made of only water and clay mixed to form a mould with no extra additive. It becomes a very sustainable material and its use can be further encouraged.

  3. Mehrzad
    October 24, 2016 at 9:50 pm #

    As Erik mentioned in the lecture, old existing architectural terra cotta is often more involved in its failure detection mostly due to the steel anchorage systems present, and only a remote visual inspection is not enough.

    The following article is a good introduction of failure types in terra cotta. As summarized in Table 1, the two more hazardous and structurally unsound conditions of unbonded/unanchored terra cotta unit plus delaminated face shell of terra cotta require getting close to the units and mechanical sounding (with soft-face hammer) while touching the units.

    http://ascelibrary.org/doi/abs/10.1061/9780784412640.022

    Another paper (see below) by the same author talks about more advanced methods such as Impulse Response Testing and In-situ Strain Relief Testing that have been used to estimate the residual stresses at the face shell of terra cotta. These stresses may cause vertical splitting in terra cotta that is attributed to the tightness of the systems designed in early 20th century. The first method eases a quick full investigation of terra cotta in order to identify the locations that needs more through assessments. Boreseope has also been used to look at degradation or disappearance of support steel J-hooks, angles and rods by drilling small holes into terra cotta that may also act as weep holes helping drainage of the water from terra cotta.

    https://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP11468S.htm

  4. Yingzhe You
    October 24, 2016 at 9:43 pm #

    Terra Cotta was one widely used all over the world and I was thinking if it is still used by some architect now. I googled online and find some interesting introduction of terra cotta modern buildings and I’d like to share with you all.
    http://architizer.com/blog/contemporary-terra-cotta/
    As mentioned in the article, terra cotta is a really good material for facade use, and this old material looks really good in the modern style buildings.

    • Di W
      October 24, 2016 at 9:51 pm #

      Yingzhe,
      Nice pictures!
      I have told you Terra-cotta is still being used in building facades. Look at those pictures of modern buildings, aren’t they brilliant!

    • Yemi O
      October 25, 2016 at 12:44 am #

      Very interesting. I have actually seen/been to some of the places in NY but never took time to notice the facade material. The material looks very aesthetically pleasing so I wonder why it is not being used as frequently

  5. Namwook P
    October 24, 2016 at 2:48 pm #

    Thank’s, Mr. Valentino for your presentation.

    It was very good time to learn about the Terra-Cotta. It is excellent material for the facade in the region of high or low temperature.
    I was wondering about the resilience for the earthquake. I think that the material is also a brittle material like brick and concrete.
    Is it available method to be reinforced such as reinforced concrete?

    I think that using this material, it is possible to reduce use of concrete. the concrete is quite not good for an eco-friendly material because of carbon dioxide gas.

    • Shubham
      October 24, 2016 at 11:38 pm #

      Namwook P, first question I had was, is Terra-Cotta as good as concrete in compression?

      I applaud to your thought and did some research. The PCI Standards link below says, compressive stregnth of Terra-Cotta to be 6000 ksi.
      https://www.pci.org/uploadedFiles/Siteroot/Design_Resources/Guides_and_Manuals/_Related_Content/PCI_Standard_Architectural_Terra_Cotta.pdf

      I think its the bonding of Terra-Cotta with rebars which holds us back from such exploitation. On the contrary, reinforced concrete has workability advantage (no kiln required), and the good bondage adds up to it.

      I read an article which states of usage of Terra-Cotta and tie-beams, in Masonry arch floor construction, but separately leading to a composite action. Have a look- http://www.structuremag.org/?p=430

      • Joe H
        October 25, 2016 at 8:34 am #

        I think it is also important to note that many of the issues that Mr. Valentino showed us were in areas where excessive rebar was used or where rebar deteriorated. The use of rebar appears to really only be a tie back and installation method for the terra cotta, and doesn’t do much for it from a structural standpoint.

        If there were a way to reinforce the terra cotta, maybe not to withstand extremely high loads but simply to limit deflection, this could go a long way in preserving terra cotta facades and making it a much more durable material than it already is, especially on places like corners where we saw a lot of issues during the presentation

    • Prateek Srivastava
      October 25, 2016 at 8:28 am #

      Hey, Namwook

      http://www.archdaily.com/32778/nbk-terracotta-facade-panels-hunter-douglas-contract

      http://www.articlesfactory.com/articles/home-business/the-advantages-features-and-factors-of-the-terracotta-panel-and-wall.html

      As mentioned in the articles in the link shared above there are many advantages of terracotta being used as an external facade.

      Answering to your question regarding resilience of facade there are cases like, Antigua in Guatemela which has been through many earthquakes and volcanoes but it still boasts of it magnificent building etc with terracotta facade.

      Apart from the strength of bonding between the facade and the actual structure, the resilience depends on the building structure as a whole, so if there are proper provisions for base isolation,in my opinion the facade will automatically will perform at its best and will serve its serviceability period.

  6. Ommar E
    October 24, 2016 at 10:59 am #

    Advantage through variety!

    A lesson I learned from Mr. Valentino’s lecture is that most of the failures in architectural Terra-Cotta façades were historically due to the failures of the supporting material and the improper building techniques. As we have seen in one of his repair examples, Mr. Valentino has managed to put back the same Terra-Cotta that existed in the building after revamping its support system and gave the façade another 75 years of age, while preserving the original look of the building. So, given the advantages Terra Cotta I was wondering if contemporary building envelope assemblies could accommodate for the needs of this building material. Since, visuals are very important when it comes to understanding of façade and its components I searched for photos and videos that deals with Terra Cotta. The manufacturer promotional video provided below shows the journey of architectural terracotta from clay raw material to its final use on buildings along with very good information on the properties, in how it withstands the elements, and modern installation techniques. It is a nice watch! Architectural Terra-Cotta is alive and well.

    NBK ARCHITECTURAL TERRACOTTA
    https://www.youtube.com/watch?v=TJc6W80V0nU

    • Yamile R
      October 25, 2016 at 12:48 am #

      Ommar, thanks for sharing the video. I have seen the use of terra cota on newer buildings. I actually got the opportunity to participate in the design of a corporate building using a ventilated terra cota facade.

  7. philr
    October 21, 2016 at 11:01 am #

    I wonder if the future of terra cotta will be like plaster..still available if you really want to use it, but finding someone (like Mr. Valentino and his craftsmen) who understands how to work with it properly, will be the primary concern.

  8. Shubham
    October 20, 2016 at 8:55 am #

    A great presentation by Mr. Valentino. Such beautiful buildings had terra-cotta facade which I didn’t realize while I passed through them, prior to presentation. The order of discussion, rationale, evaluation, failures, repair took us from introduction (the basics) to the restoration techniques. The photographs in presentations were great in explaining the timeline of failure.

    With the examples of steel corrosion, it was clear that as a forensics engineer you should focus on underlying cause of failure not just effect, else the result would be more uneconomical or even hazardous.

    With this one cannot undermine the vulnerability of water, so the steel should be anti-corrosion coated or proper flashing should be provided.

    What are stress induced failures in Terra Cotta, apart from thermal stresses?

    I have a very basic question. We all know that facades aren’t meant to carry any load, but what about their thermal stresses, self weight, self-intactness, their interaction with other components. So, do facade need any prior analysis?

    • ErikS
      October 24, 2016 at 12:01 am #

      Shubham, please see my response to Alec B under Joe H.

  9. Prateek Srivastava
    October 20, 2016 at 8:01 am #

    The presentation about Terracotta facades was an exhaustive one.

    Terracotta has been used in different parts of the world in one form or the other like in sculptures, buildings etc.

    The first advantages of the Terracotta Panel are the special design of the surface. The color of the Terracotta Panel has been determined by the clay qualities and without any dyes and thus it contains the natural colors which is not easy to be faded. The brightness of the color of the Terracotta Roof Tile could be changed with natural light and weather from outside.

    The second advantage of the Terracotta Panel is the combination of traditional and modern. The clay for the Terracotta Panel is one kind of the mild material and it is easy to be used with glass, metal and wood which would maintain the coordination of the Wall Facade Panels.

    Though it has some of the advantages as mentioned it has to be installed with proper workmanship so that there are very few chances of water penetrating in the interiors of the facade which we have seen in many cases is the root cause of many failures. It leads to corrosion of the steel joining the terracotta with the structure its plastered on. There are chances of spalling etc which are to be looked for while maintenance work.

    The question being what should be the duration of a routine maintenance work for a building having terracotta facades?

  10. Joshua Z
    October 20, 2016 at 2:14 am #

    I found Mr. Valentino’s lecture on terra cotta to be very interesting, as I had never been exposed to the material and its use outside of roof shingles in the southern United States. It was great to learn about how to identify terra cotta facades and learn about its use in architecture throughout American history. His presentation touched on a few of the main points we have been discussing throughout the semester, including quality of workmanship and the importance of maintenance. A particular instance of this that stood out to me was the part of his lecture referring to the corner of a roof, where it was falling apart. The owner, or whoever did the repairs, jammed mortar into the cracks of the terra cotta in order to “fix” the problem. While this may have “fixed” it aesthetically, it still damaged the terra cotta pieces as the mortar held the water and only made the damage worse. Another part of the lecture that stuck out to me was his discussion of short-term lintel repair, when he said that while the short-term fix did the job, it did not solve the underlying issues in the long run. This ties back to the concept of maintenance that we had discussed in Mr. Pirro’s lecture about concrete deterioration. In his lecture, he brought up points about how the earlier you fix the issue, the less expensive it will be in the long run. This concept applies to terra cotta as well. If you fix the failure early on, the cost will be significantly less than it would be if you were to repair it later.

    It is also unfortunate that use of terra cotta has become less prevalent in architecture today. It has proven to be versatile in many ways, and I would wonder what it would take for it to become a popular building material again.

  11. Brendan B
    October 20, 2016 at 1:28 am #

    Mr. Valentino’s speech about terra cotta was very informative as this is my first time being exposed to the material. The only previous time I heard about terra cotta was in an architecture class, which did not contribute much to my structural background. When I first heard of terra cotta, I thought of it more as an architectural material instead of a structural material.

    One of the most interesting parts of Mr. Valentino’s presentation was seeing pictures of several of the poor repair attempts, and the point he made about how making a poor repair does more harm than good. Similar to concrete, water can get into the material and cause issues such as spalling and corrosion if not repaired properly. As with any building material, it is important to repair before the problems escalates and gets worse. With terra cotta, it is even more important to repair as falling pieces can pose a safety hazard to pedestrians on the street below. It was certainly a pleasure to be exposed to a practice that is not as common in the industry.

  12. Mehrzad
    October 20, 2016 at 12:45 am #

    It also was my first exposure to terracotta and I enjoyed the lecture given by Erik. As he mentioned, figuring out underlying causes of the failure in terracotta is the first step prior to taking any remedial action specially when full replacement of terracotta is expensive or deemed unnecessary at the first look.

    Two main improvement components that need to be addressed in repairs of terracotta systems are structural integrity and moisture control.

    Building designers in the early 20th century did not pay enough attention to relative movements of structural and architectural elements that would subsequently introduce cracks in the claddings. This tight setup could be one of the reasons where larger cracks propagate in terracotta (this concern is addressed with joints in newer masonry walls or deflection tracks in cold-formed wall assemblies, etc). This makes periodic record of the crack openings in terracotta important (as Erik mentioned in one of the slides). Depending on the stationary cracks or cracks with limited movements, various repair systems may be used (page three of the following guide)

    http://www.edisoncoatings.com/html/REPAIR_OF_ARCHITECTURAL_TERRA_COTTA.pdf

    For moisture prohibition, one lesson from the lectures is that the seemingly easy and cheap solution of caulking or otherwise waterproofing the joints worsens the situation entrapping the water inside. A well-designed flashing and usage of mortars with less compressive strength than terracotta (to not constraint movement of the terracotta and consequent cracking) in the joints are successful scenarios.

  13. Shane M
    October 19, 2016 at 11:20 pm #

    The terra cotta presentation revealed a side of forensic engineering that I never expected to come across. The only use of terra cotta I have ever learned about is the standard red terra cotta roofing shingles that are popular on southern homes. Mr. Valentino made some great points about how owners should always put in the time and money to preserve their terra cotta cladded structures. They are in possession of a significant piece of history, and also a damaged façade could pose a potential threat to pedestrians below.

    I see that there always seems to be an issue with failures caused by poor workmanship or misguided installation of a system. The lack of knowledge in the industry on terra cotta and its applications is unfortunately affecting its feasibility in the long run. Owners will continue to see it as more of a hassle than a possible choice of material. I would like to ask, is there any chance that this material could be making a comeback?

    • Joshua Z
      October 25, 2016 at 1:27 am #

      Shane,

      The only way I see the material of terra cotta making a comeback is for more people to become more educated on the proper way to use it. However, while the information age has made it possible to learn about anything and everything, it seems that only a select few have the required knowledge and skill to properly use terra cotta as an architectural material. So, it would take a great deal of time for more firms and people to become properly educated on the use of terra cotta in construction. And even so, this would come with a great learning curve. As you mentioned, there seems to be an issue with failures caused by poor workmanship or misguided installation of a system. Thus, there would be a lot of work for the the firms that know how to deal with terra cotta if it made a comeback, because those who are just starting out would make mistakes before mastering its use.

    • Brendan B
      October 25, 2016 at 1:48 am #

      Shane,

      The running theme of the different building enclosures that we have been exposed to seems to be how poor workmanship can decrease the life of the material. Similar to installing flashing incorrectly with wall water barriers, poor terra cotta repairs can also trap water within the material leading to these problems. Unfortunately poor workmanship can have such a great effect of the deterioration of these materials, when it can easily be avoided with proper education of the installation of the material.

      This ties in to your question whether terra cotta can make a comeback. One of the main reasons terra cotta had a fall out was due to the difficulty in identifying causes of deterioration. If more engineers are aware of how the material behaves and how to restore it properly, a comeback could certainly happen. Once more buildings are using terra cotta, more people will be exposed to the material and be more inclined to use it.

  14. YusufA
    October 19, 2016 at 10:49 pm #

    I must admit that the presentation of Mr Valentino was an exposure to a different use of Terra-Cotta for me.

    I have been in contact with the materials usage back in Nigeria but majorly for flooring purposes. Its use has also gradually been phased out as it is in the United States with many homes and buildings opting for the use of Marble and majorly Ceramic Tiles instead.

    However, I used to always wonder if the material was unreinforced but now I understand that there is a significant amount of anchors at specific places placed in the glazed architectural Terra-Cotta and anchored into the building for support.

    Just like many other previous lectures, the importance of preventing water was again highlighted and this is an aspect that would still need to be carefully considered for repair works and new installations.

    One thing that I also learnt was the identification guidelines which I almost immediately put into practice after the class.

    PS:I think I may have stumbled upon the first set of Terra-cotta flooring on campus at the main entrance staircase of Boucke Building. This was just a test of my Identification knowledge and I hope I can be corrected if I saw the wrong material type.

  15. MichaelB
    October 19, 2016 at 10:13 pm #

    Mr. Valentina’s presentation was very informative for me as I feel I have not learned very much about Terra Cotta. I didn’t realize how indistinguishable terra cotta can be from traditional stone masonry. The terra cotta moldings that mimicked granite were especially convincing.

    Mr Valentino mentioned how you can tell Terra Cotta apart from stone at spots where it’s chipped and you can see the inner layer of the terra cotta. You can also tell it apart by the micro cracks he mentioned that have a very distinct look. I would be interested to know what other indicators there are to identify terra cotta in newer buildings or buildings were the terra cotta was installed properly and well maintained so there are no spots spalled off where you can see the inside of the terra corta.

    • MichaelB
      October 24, 2016 at 11:30 pm #

      From reading an article entitled “Architectural Terra Cotta”, people involved with the terra cotta industry during the early 20th century did understand that water could enter the terra cotta wall system through joints in the units and that installers should avoid filling the voids for areas exposed to moisture. The article even mentions that some terra cotta buildings during the 1920s began to use water control methods such as flashing especially at copings below parapets. This practice was quickly stopped because of the Great Depression unfortunately. Although flashing is rare for old terra cotta buildings according to the article, it could serve as another indicator that the cladding on a structure is terra cotta and not stone.

  16. Ishan Uppal
    October 19, 2016 at 9:17 pm #

    Mr Valentino’s presentation on architectural terra cotta was fantastic introduction to the building material. I was completely unaware of its uses and properties.

    It was amazing for me to find out that a material that was almost obsolete since the 30’s is seeing a resurgence now. A sign of the times and trends I guess. However it does posses certain properties that are optimal for its use in preservatuon. The brilliant colors achievable with terra cotta make it an exciting material for use in facade design.

    During the presentation, once again it was clear that water management with terra cotta, as with other structures is very important to prevent failure and damage. The section loss experienced by the steel anchors needs to be avoided by protecting them from corrosion or by using non corrosion materials.

  17. Ommar E
    October 19, 2016 at 9:13 pm #

    Thanks to Mr. Valentino for an eye opener lecture on Terra-Cotta. The issues touched upon by the lecture such as rationale, evaluation, failure and repair are at the heart of understanding of this facade/externally used building material. I, now, know for sure how large number of building that I passed by thinking that the facade building material is, while it is actually Terra-Cotta. I could also see how this building material was a victim of its own success. Suddenly, you have a building material that resembles many very fashionable and expensive externally and sometimes internally used building materials that is not only less expensive but also very malleable with variety of colors. The wide spread use before developing the right installation techniques and supporting materials that last the lifespan of terracotta itself. As known, from discovered artifacts from thousands of years how durable this material. In addition, it is an environmentally friendly material that with evolvement of new building techniques and affordable corrosion resistant supporting materials is bound to resurface as a viable choice for architects, engineers and owners.

  18. Yamile R
    October 19, 2016 at 8:26 pm #

    I think Mr. Valentino’s talk was very interesting. I myself was not very familiar with terracotta material, and learned a lot about its common failures and ways to repair it.

    From the lectures, we learned that terracotta is used to imitate other materials such as granite, and that it is used to repair and renovate old structures. If it is possible to use terracotta to reconstruct elements, what is the advantage on using it instead of the original material?

    • Rebecca M
      October 24, 2016 at 10:30 pm #

      Yamile,
      I looked further into terra cotta façade manufacturers and found various reasons as to why terra cotta itself is a great material choice. The manufacturer Favemanc in Spain described their façade system’s advantages as energy savings due to insulation properties, reductions of acoustic reverberation, ability to withstand extreme temperature variation, and its wide range of colors and finishes. The link to their website is included below for reference. To me, it seems these advantages are what makes terra cotta such an appealing façade material and its versatility in color and finish create the appearance of various other material while keeping the benefits. As for reconstructing elements, I wasn’t successful in finding a reference regarding replacing other materials with terra cotta pieces because it has a high increase in cost and production time but there are instances where the damaged terra cotta façade is replaced by suitable substitute materials such as stone, fiberglass, precast concrete, and glass fiber reinforced concrete as described on Masonry Preservation Services website. The advantages of the situation of replacing the damaged terra cotta stems from a lower overall cost and potentially a shorter lead time. The only drawbacks would be losing the terra cotta’s material properties and composition.

      http://english.favemanc.com/wr-advantage-facades-terracotta#
      http://www.masonrypreservation.com/services/masonry-restoration/terra-cotta

    • Shane M
      October 25, 2016 at 1:23 am #

      Yamile,

      I believe the major advantage of using terracotta as a repair material comes down to its cheaper costs and the ability to mold it into complex shapes and patterns. Carving a new piece of granite would be both expensive and difficult as it would require someone with experience. If the terracotta can be coated to resemble an original material, then I do not see any reason not to use it for the repair.

      • Yamile R
        October 25, 2016 at 12:23 pm #

        Thank you Rebecca and Shane.

  19. Rebecca M
    October 19, 2016 at 7:18 pm #

    Tuesday’s presentation on terra cotta facades was a great introduction to the history of its use in architecture and how it stands today. As with many other topics brought up in this course, there is always more than one way for something to fail on a building. An interesting point in the terra cotta lecture however is the fact that it is the structural support of the terra cotta that fails, rather than the material itself. With that in mind and after Mr. Valentino’s concise explanation of the typical details that support the terra cotta, it is much easier to understand how the material has failed.
    Again, as with many other topics moisture plays the largest role in the failure due to the corrosion of the steel joining the terra cotta to the main structure. Once signs of chipped glazing or spalling are observed and the investigation begins, how long does it take to remove the materials in order to expose the mild steel holding the terra cotta onto the structures? Also what are the chances that the testing itself taking place causes something corroded to fail? With the outdated practice of filling the terra cotta with brick and mortar or other materials, it seems like that creates more things that you would need to remove very carefully in order to investigate the actual support without damaging anything.

  20. Joe H
    October 19, 2016 at 11:39 am #

    One of the biggest parts of the presentation that stuck out to me was the history and usage of terra cotta as a building material. The timeline laid out by Mr. Valentino definitely made sense, and it is noteworthy that by the time that producers were able to complete their efforts in understanding and preventing deterioration, terra cotta had gone out of popularity, despite having been used with great aesthetic success on many buildings.

    My biggest question is to what extent is terra cotta still used today? I can see that it was a great solution in the early 20th century for neo-classical buildings because they could get the beautiful stone, marble, or granite look they wanted for much cheaper. Now, it seems like the need for terra cotta is much much less. Many buildings now are going for a much more open, modern, sleek feel, to which I don’t believe terra cotta is very applicable. While preservation is definitely important, it is intriguing to think that terra cotta could soon become a lost art, as the demand seems like it should be declining.

    • mkev
      October 19, 2016 at 12:25 pm #

      Joe,
      Terra-Cotta is having a second life in the building industry but not in the form of detailed architectural assemblies. Much of the use is in Terra-Cotta panels for modern curtain wall buildings. One advantage is an unlimited color palate. One of the 4 Terra Cotta Challenge Penn State buidlings is of fairly recent construction and includes such panels. Can you figure out which one it is?

    • Yemi O
      October 19, 2016 at 5:27 pm #

      Joe,

      Terra-Cotta is still heavily used in places like China. During my study abroad, I had the opportunity to see some buildings with terracotta wall panels, however, they are mostly common in the rural/ local areas.

      A modern use can be see in the “Jingdezhen Ceramic Art Building” in china, which is used as a facade panel. You should check it out.

      • Yingzhe You
        October 19, 2016 at 9:11 pm #

        Yemi,
        Yes, there are still many terra cotta buildings remaining in China, but in really rural areas. Most of them use terra cotta tiles for their roofs. But with the development of urbanization in China, more and more countries near cities become to satellite cities so those terra cotta buildings are replaced by the high rise reinforced concrete buildings and even steel buildings.

        What’s more, terra cotta as a famous material in the past even does not have a chance to appear in any of my undergraduate textbooks. Maybe in the near future, we are only able to see terra cotta buildings as tourist attractions. Is tearing all those old terra cotta buildings down and using concrete or other materials with better performance instead a really good idea? I’m still thinking about it.

        • Di W
          October 19, 2016 at 9:24 pm #

          Yinzhe,
          I think Terra-Cotta is still being used in construction such as building facades.While many new products for cladding a façade have been introduced to the construction industry in the years since terra cotta had its hey-day, few have come to surpass terra cotta in longevity, aesthetics and sustainability. Terra Cotta continues to be a material of choice for many designers because of its malleability with regard to shape and texture, its abundance of finish options, its compatibility with other building products, as well as its ability to withstand severe climates both for freeze-thaw and uV resistance.

    • Alec B
      October 21, 2016 at 11:42 pm #

      Joe,

      In response to your post and serving as a continuation of MKev’s post, I found a specific manufacturer of terra-cotta panels used as part of modern curtain wall assemblies (similar to the panels of the new Hub addition). To summarize, TerraClad Ceramic Rain Screen System (by Boston Valley Terra Cotta) is comprised of durable yet lightweight terra-cotta panels on an aluminum framing system. The terra-cotta panels offer a more modern aesthetic for the building and offer many benefits over typical terra-cotta masonry design, installation, and maintenance. The panels come in many colors and textures. I encourage you to check out the link below to reference material that gives an overview of the material while also showing color/texture options as well as installation details.

      http://bostonvalley.com/products/terracladtm/rain-screen/

      • ErikS
        October 24, 2016 at 12:02 am #

        Alec, NBK (http://www.nbkterracotta.com/en-US/home.jsp) is also an architectural terra cotta manufacturer and designer, used throughout the world. Terra cotta is definitely still in use in varying methods. The rain screen is one of the most prevalent today due to being relatively light weight and, as Di mentioned the ability of the material to take on many shapes, colors, and textures its UV resistance and freeze-thaw (if designed and installed properly).

        Which brings me to a response to Shubham’s question regarding design loads and analysis for facades, or more specifically veneers or curtain walls where no bearing load is intended to be carried by the cladding, other than self-weight. Facades components are definitely analyzed and designed to accommodate thermal (both for expansion/contraction and thermal comfort), gravity, wind, and seismic loads. Joints between components must be designed to accommodate the anticipated design movement. Connections back to structure must be stout enough to minimize the risk for fall hazards but must allow movement to accommodate those expected in the design. Generally it is not the cladding components that are the weak point but as we have found it is often the joints that fail either through lack of proper design, improper installation, or deferred maintenance, which then allow water into the system to cause whatever havoc it may. Additionally, when movements are not accommodated for thermal expansion, seismic, wind, etc. can cause the various components to come into direct contact with each other and materials such as brick, stone, terra cotta, etc. are quite brittle and may crack or spall and can become a fall hazard.

        • Shubham
          October 24, 2016 at 10:51 pm #

          ErikS, thanks a lot.
          I visited the website ErikS mentioned, and encourage others to go through the U.S. projects. One can see distinguish thermal expansion/ contraction accommodated in various designs of cladding.

  21. Alec B
    October 18, 2016 at 10:47 pm #

    Mr. Valentino’s talk exposed me to architectural terra cotta facades – a topic in which I was not familiar with prior to this morning’s presentation. I was surprised to learn how difficult it may be (to someone who isn’t as familiar with terra cotta as a building material) to identify terra cotta in building applications. Even with some of the photos Mr. Valentino shared with us this morning, it was not immediately apparent to me that the facade material was in fact terra cotta. I was also interested to learn about the “inner workings” of terra cotta facades. I was unfamiliar with all of the supporting elements that are tied into terra cotta facades, and Mr. Valentino’s example photos of deconstruction and his hand sketches helped me to understand the system better while also illustrating problem areas in the event of a building failure. As Mr. Valentino explained and as the Preservation Brief 7 reiterated, terra cotta itself usually doesn’t fail; instead, the installation fails or the adjacent materials fail. Designing and constructing a “breathable” terra cotta facade seemed to be highlighted in this morning’s talk; issues appear to arise when constant moisture is held within over-packed brick, mortar, etc. that composes the structure beneath the terra cotta facade. As mentioned in Preservation Brief 7, “Repointing of mortar which is severely deteriorated or improperly or infrequently maintained is one of the most useful preservation activities that can be performed on historic glazed architectural terra-cotta buildings.” Mr. Valentino showed several photos of architectural terra cotta facades in need of repointing. How is the repointing process typically completed? In some instances, it seems like there is severe deflection that creates large gaps in the terra cotta that needs to be corrected; it is difficult for me to visualize how such large deflections over time may be corrected by repointing.

    • ErikS
      October 19, 2016 at 5:48 pm #

      Thank you Mr. Valentino for your presentation.

      Alec, once again it is demonstrated that moisture plays a major role in material deterioration on buildings and structures that can lead to structural deficiencies, failures, or collapse. The repointing work is performed to maintain what the designers intended to be a watertight barrier at the surface of the terra cotta. The desire and belief was to keep the water at the surface so it would never be at the interior to soak the fill material or corrode the steel; however, as we have seen mortar debonds, terra cotta moves and cracks, other materials move and crack and you get water beyond the exterior surface and the deleterious effects of moisture, freeze thaw, and corrosion take over.

      The expectation of repointing is that you will minimize and control the majority of the bulk water from migrating into the structural side of the terra cotta. The problem is maintenance work such as repointing does not occur often enough (if at all) and then you begin to have the deflections and gaps form, which then are objectionable both from an aesthetic concern to the owner but also a perceived safety concern from the owner (which often times is warranted). This is the point when often uneducated (I use that term in meaning not knowledgeable in proper methods of restoration or where to look for assistance) tell their maintenance crew to seal it up or patch it as Mr. Valentino (and our previous presenters) explained and the initial displacement progresses to a point the safety concern is no longer only perceived but actual.

      Again, the $1, $10, $100 rule applies; look at the example of the corner cornice that they had to demolish and take down to base steel structure and rebuild. Obviously this deficiency had been observed previously based on the “repair” attempts with the sealant and mortar fill were the terra cotta units no longer were level. This could have been maintained at a much lower cost with proper pointing or application of sealant (if necessary) or flashing ($1), then repaired when the displacement was first noted, likely with minimal structural deterioration due to corrosion ($10), but instead the major repairs were required to replace and supplement steel and damaged terra cotta sections ($100). This owner is lucky the terra cotta did not fail and collapse and cause personal or property damage.

  22. mkev
    October 18, 2016 at 12:26 pm #

    Terra-Cotta Challenge: There are four known campus buildings with clay tile and/or Terra-Cotta as a part of the visible external construction on campus. I challenge the AE 537 Class to identify them all. In at least one case, you may need to use the identification techniques discussed by Mr. Valentino (the non destructive ones of course).

    • philr
      October 19, 2016 at 8:14 pm #

      Weaver, Armsby, Patterson?

    • Prateek Srivastava
      October 20, 2016 at 7:43 am #

      1. Hub south facade
      2. Millennium Science Building
      3. Botany Building roof ridge
      4. Carnegie Building the motifs and columns

      I hope these are correct.

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