Didi and Sandi Pei designed the Bank of China Head Office Building in Beijing, China, with their father I.M. Pei. Italian Roman classic travertine defines the building inside and out. All of the stone was extracted from a single quarry by Mariotti Carlo & Figli Srl in Tivoli, Italy.

Chien Chung (Didi) Pei, AIA, and his younger brother Li Chung (Sandi) Pei, AIA, not only share a family bond, but they also both have a passion for architecture. As a result, they set out on their own in 1992 and opened Pei Partnership Architects in New York City. Before beginning their own endeavor, however, the two gained valuable experience in designing large-scale buildings while working under the tutelage of their father, I.M. Pei, for nearly two decades.

Didi Pei earned a Bachelor of Arts cum laude in Physics from Harvard College in 1968. Four years later, he graduated from the Graduate School of Design with a Master’s Degree in Architecture. Prior to founding Pei Partnership Architects with his brother, Didi Pei spent the first 20 years of his professional career contributing to a range of prestigious projects at I.M. Pei & Partners (now Pei Cobb Freed & Partners), including the Grand Louvre in Paris and the National Gallery of Art in Washington, DC.

While at I.M. Pei & Partners, Didi Pei developed nationally recognized expertise in museum architecture and medical facility design. Last year, in collaboration with Perkins+Will, he served as Partner-in-Charge for the 1.2-million-square-foot Ronald Reagan UCLA Medical Center, which was dedicated on June 4, 2007. Additionally, Didi Pei is leading the design of the U.S. National Slavery Museum in Fredericksburg, VA.

Sandi Pei earned a Bachelor of Arts magna cum laude from Harvard College in 1972, and a Master’s Degree in Architecture from the Graduate School of Design in 1976. Upon graduation until starting Pei Partnership Architects in 1992, Sandi also worked at his father’s firm.

Project types that Sandi Pei has worked on since the beginning of his career include educational facilities, laboratories, museums and commercial offices as well as hotels and residential designs. Among his award-winning projects are the MIT Arts + Media Technologies Facilities in Cambridge, MA; the Creative Artists Agency Headquarters in Beverly Hills, CA; and the Bank of China Tower in Hong Kong.

Since founding Pei Partnership Architects, Sandi Pei has directed the design of almost 11 million square feet of building space and several large-scale urban development projects in the U.S., Mexico, China, Indonesia and Singapore. Among his projects currently under construction are the Industrial and Commercial Bank of China Headquarters in Beijing, China, and The Centurion, a luxury high-rise condominium project in New York City.

Together, Didi and Sandi Pei have collaborated on world-renowned projects such as the Bank of China Head Office Building in Beijing, China, the Macao Science Center and the Suzhou Museum - located in the Pei family’s native city in China - which opened to international acclaim in 2006. Additionally, they are designing the new chancery building for the Embassy of the People’s Republic of China in Washington, DC, which will be completed in 2008.

Both Didi and Sandi Pei are actively involved in a number of professional and civic organizations, including the American Institute of Architects (AIA). While Didi Pei serves as a member of the AIA’s Delano-Aldrich Fellowship Committee, Sandi Pei is a former Director of the AIA/New York Chapter.

Didi Pei is a trustee of the Collegiate School in New York City, and was also recently elected Vice Chairman of the Board of Trustees of the China Institute in Manhattan. He has frequently been called upon to lecture to professional and education organizations on architectural design, including to local AIA chapters in such places as New York, NY; Jacksonville, FL; Memphis, TN; Salt Lake City, UT; Orange County, CA; Los Angeles, CA; and Vancouver, BC. He has served as a jury member for architectural design awards in many of these same chapters, and he has lectured at the University of Texas (Austin), the University of Michigan (Ann Arbor) and Columbia University. Moreover, he has also lectured at the National Gallery of Art and the National Building Museum - both in Washington, DC. Internationally, Didi Pei has lectured in China, France, Italy, Mexico and Aruba. He received the UCLA Medal in June 2007.

Sandi Pei has extensive experience in the fields of education and the arts, including board membership and trusteeship of schools, civic organizations and professional associations. He has also lectured widely, and he has participated as a critic at several schools of architecture and as juror to the National Endowment for the Arts and to international competitions. Sandi Pei is also a former Trustee of the New York Foundation for Architecture, and he is a member of the International Council of the Museum of Modern Art.

Stone World: When did you make the decision to pursue a career in architecture?

Didi Pei: People often ask, “Did you do this because your father is famous?” I always tell people that when I made the decision to be an architect, my father wasn’t famous. I graduated from [Harvard University] in 1968, and that was a long time ago. I got a lot of calls a few years ago when the father of one of my classmates from that same period decided to run for president. Everyone said, “That must be very interesting - your father was very famous and his father was very famous.” And I said, “When he and I were in school together, his father wasn’t famous and my father wasn’t famous.” It just really didn’t register. I just don’t think that was part of it at all.

SW: But you always had an interest in design.

Didi Pei: Well, when I was in boarding school, my parents took us to Europe for the first time. We went around and looked at all the monuments and so on. And then we did it again after I graduated from boarding school. So I had been to Europe twice before I went to college, and I had seen a lot of these things that sort of piqued my interest. But, when I was in college, I actually majored in Physics. So I think that is what I thought I was going to do.

SW: When you looked at some of the architecture in Europe, did any one building or monument in particular stand out for you?

Didi Pei: Not for me. Maybe it is different for Sandi. Of course, when you go to Europe, it is a completely different environment, so it makes it more interesting to look at. And there weren’t really projects that my father had done - at least in this country - at that time.

SW: As you progressed in your career, and your father did too, did you learn any lessons from him?

Didi Pei: Well, of course. After I finished architecture school, I worked in his office. I think that is really the key - to get good work experience. It is very important to work in a good office and learn good habits.

SW: What were some of your other influences?

Didi Pei: For me, it wasn’t really architectural. I was interested in art, and I took a lot of art courses. I was also interested in photography, and I did a lot of that when I was in college. So in a way, this was sort of a transition into architecture.

Architecture is a profession where you are working for somebody else with somebody else’s money, and you have to do a really good job. It is not the same as just being an artist where you have a blank canvas, and you can do whatever you want and then see if somebody wants to buy it. It’s not the same at all. There is a real practical side of the profession that is common to what a lot of people do. Everybody thinks that an architect is some dreamer with his head in the stars somewhere, but I think that good architecture really does require that you always have your clients’ interest in mind.

SW: When did you decide to start your own firm?

Sandi Pei: Each of us had been working in our father’s office for well over 15 or 16 years, and we came to a point where we wanted to have much more control over what we were going to do. It was a point in our careers that it was time to move out, if we were ever going to do it.

Didi Pei: My father retired, so to speak; although he never really did retire. He retired in 1990, and in 1992, it was a really slow time in the entire industry. I had just finished working on the Grand Louvre in Paris, and I was back in New York. I was working on a museum project in Luxemburg, which for political reasons stopped. So I said, “Hmm, I’m usually working on two or three projects at any one time.” And all of a sudden I didn’t have any particular project, so I had a choice of either going to the partners and asking them to reassign me, or since things weren’t really going that well in the whole industry, this actually was a good time to get out. When you get involved in an architectural project, usually it is at least four years, and sometimes it’s more. The Ronald Reagan UCLA Medical Center took 10 years. And it’s very hard to get out once you get in.

Sandi Pei: We had the opportunity at the same time to move out. A client had approached my father with a project [that we ended up working on]. You don’t move out unless you have some idea of what you are going to do.

Didi Pei: It wasn’t until much later that we got our first big project, though. We had gotten little projects at first. I had worked on something for my kids’ school. I was asked by Mount Sinai Hospital to redo some operating rooms for them. I wasn’t really worried about getting work, but then all of a sudden this project came along. They had asked my father, and he said that he was retired. They went to his firm, and they said that they were doing a project for one of the company’s competitors, so they couldn’t do it either. So they went back to my father, and my father said, “Well listen, my two sons have started a little office. I would suggest that you talk to them.”

SW: Once you started your own firm, did you begin to pursue other project types? Were you going after something different in terms of size or client?

Sandi Pei: Good question. Of course, we were going after whatever we could get. But my own inclination since, and my own focus, was to [continue] to do the same type of work in our own practice. Because that was the scale of work that we were trained to do. I didn’t really want to do kitchen renovations, and I didn’t want to do single-family homes.

Didi Pei: You find that each different building type and each different building size is a whole different sector of the profession. I think that both of us were much more comfortable in large-scale commercial and institutional projects.

Sandi Pei: It’s good and bad in the sense that this is a sector that not everyone comes to and says that they can tackle. But at the same time, for a small practice like ours at the time, we were competing with all the big firms - and with firms that had a much bigger track record. We had no real track record of our own at that point in time. So, we were fortunate to have this one project, Sentra BDNI, with which we were able to start. It was a very big project - 3.5 million square feet. It was in Indonesia. And that was the kind of project with which we were going to build a practice. We spent three or four years before it went into construction.

Didi Pei: I don’t think we knew how big it was when they came to talk to us. Like a lot of things, it just became bigger and bigger and bigger. The piece of land got a little bit bigger, and then they obtained another piece. It was a wonderful client. We have had an ongoing relationship with them. It has led to other opportunities. It’s wonderful that we have repeat clients. I think that is a key to developing your own office - to develop good relationships with your clients as well as with the consultants with whom you work. We did get a lot of work from both of them.

SW: When you started, was it just the two of you?

Sandi Pei: Yes. It was just the two of us, and then we grew. Now we have about 40 staff members. It’s a nice size.

SW: How involved are your clients usually when it comes to selecting materials?

Sandi Pei: It really depends on the kind of client. Obviously, some clients are very involved and come with a great deal of knowledge and their own group experience and predispositions. And they come to say that they admire that kind of work, and they know what they are going to get - standard quality. Others wait until we offer our suggestions.

Didi Pei: I agree. It depends on the client. Some clients have a very strong idea of what they want, and others really want the architect to make a recommendation. So we get both.

Sandi Pei: Of course, we are supposed to be much more on the cutting edge - much more versed in the latest materials and the way of doing things. Nowadays, buildings are increasingly environmentally friendly and apply some of the highest industry standards. [Our clients] don’t necessarily know them, so this is why they come to us.

SW: Specific to stone, do you often have clients that want to use a particular stone on a project?

Sandi Pei: No. I think that we really come with the knowledge about the use of stone, what is appropriate, what is suited to the climate or the environment - whether it is granite or marble.

Didi Pei: And it is also very important to know what the price is. I mean, these stones have very different prices, so a lot of that goes together. We always try to give our clients a choice. We will have in our mind some sort of general color range and visual idea of what we want the stone to look like if we are recommending stone, but then again, we always give them a choice. And included with the choice that we propose for them is, of course, the price.

SW: What sources do you use to learn about new stone products on the market?

Sandi Pei: We are very aware of who the various quarry producers are, what is being produced, what is coming out these days, where it is coming from, what the prices are, what the strengths are, and what the production schedules are of these various materials. We need to know that. In order to make a recommendation, we need to know quantities and the delivery schedule as well as technical information.

Didi Pei: There are people inside the industry who are not necessarily suppliers themselves, but have very good knowledge of the various types of stone. In fact, the information is changing all the time. Because stone is a natural material, a stone that was used on the last project may suddenly be unavailable. You have to know these types of things. Or maybe you will find out that for another stone that you really like, that particular quarry is backordered for four or five years, and it’s not going to be available either - no matter how much money you are going to pay.

Sandi Pei: Often times, even the quality and color of material has changed over time. They can be at a different bench of the quarry, and the material coming out may be entirely different; there may be an unattractive aspect. So, you do need to know that.

Didi Pei: I remember looking at one particular quarry that was very slow, and in order to keep the people working, they actually quarried all of these blocks. They were just sitting out there, and nobody was buying them. But because they are also fabricators, they need people working in the factory. I was told that if I wanted to come in and place a large order, I would get a really good price on this stone. A few years ago, it was very expensive. So for these people who are in the stone business, it can be tough.

SW: It does change, and the opposite is also true. Sometimes a stone that is generally considered to be reasonable in price and readily available becomes tough to get. Then people find themselves paying a premium for it. It is really something to keep on top of. So for a project like the Ronald Reagan UCLA Medical Center, did you have a stone consultant or other people visit the quarries?

Didi Pei: We had a stone consultant, who was Marc Heinlein. But also, we took the client to visit the quarries to actually look at the material that we had already selected. You can’t just go all over the world and turn it into some kind of a junket. It was a very focused trip looking at different stones that we could recommend.

SW: Do you do that with your clients for most of your projects?

Didi Pei: Yes, we do.

SW: What are some practical lessons that you have learned working with stone over the years?

Didi Pei: I think it is just like anything. For example, even when you have a range of stones that you like, you still have to do a lot of research. For example, with some stones, there is a limit to how large you can get them. A lot of people would never even think about that. They would say, “I like that stone,” and then they go through all the work, and they do all the detailing and everything else, and then all of a sudden, they find out that there is a maximum size. Then all of a sudden, you are really in trouble because you have set everything by then - your window sizes and everything else. You have to do a lot of research. You just don’t look it up in some book or you don’t look it up from some little samples; you have to really go all the way.

SW: I suppose that is a lesson that also takes place in-house with some of your younger associates. You have to educate them on what needs to be done when specifying stone.

Sandi Pei: I think that most of these decisions about selection of stone happen at a level where the principal involved offers design direction on the project. But, of course, those who are executing those drawings and doing the detailing need to know and need to work with a technical specialist in anchoring.

Didi Pei: They are learning more and more about how to put things together.

Sandi Pei: I think the other aspect is that stone is a natural material, and that is one of the things that you learn. And that is why stone is so interesting, and that is why stone use has different characteristics and problems and challenges. We have had times when stone has been cracking, and you have to understand why. Sometimes stone has been sitting on the site and gathering water, and then of course, freeze/thaw cycles are a problem that we have encountered before. And, as we were saying earlier, sometimes the stone is not as advertised because you hit a different bench in the quarry, and suddenly the stone that you recommended isn’t actually the one that you wanted.

Didi Pei: In our office, we have a very active continuing education program, which applies to all aspects of architecture - particularly different materials and so on. So we will have people from the stone industry come in and make presentations. They are quite well attended in our office. These are the many ways that younger people can learn about material.

Sandi Pei: And people like stone because it is a natural material. And that’s why people tend to be attracted to stone. That’s why every piece looks different, and we enjoy seeing how it is laid up.

SW: Do either of you recall a particular positive or negative experience when using stone?

Sandi Pei: I had mentioned that we had a situation where some stones had been sitting around in crates. They actually came wet - all the way from Italy. So they were sitting in a wet environment during the winter.

Didi Pei: The contract documents [provided to the stoneworking company] are not just the drawings. The documents are the specifications, which will and should cover the way in which the material is handled. And I think that it is important; a lot of people don’t pay much attention to that aspect. So, when we say “contract documents,” it is the drawings and the specifications.

SW: On the positive side, are there any stone projects where you were able to achieve something in stone that hadn’t been done before?

Didi Pei: If you put it that way, I think about a project that I was working on when I was in my father’s office, which was the National Gallery of Art in Washington, DC. First of all, we had to reopen the quarries to get the stone. Second of all, the stonework was designed as it had been done for the original National Gallery of Art. The stones were actually laid out on the ground - all of them exactly the way that they would have been put up on the building. And since they are all slightly different from one another, they could be moved around, and the location was actually determined for each stone.

We did achieve one thing for that building, which I don’t think has ever been done before or since. In order to get very small joints over an extremely long length without any interruption in plane, each stone was individually supported with gaskets in between and not mortar. And on the outside of the building, we actually had 1/8-inch joints over the whole building - for a length of over 450 feet long. It was a straight wall. So I think that is one of the things that when you know what you want to do, you really work hard, and figure out a way to do it.

Sandi Pei: Also, pioneering some technical details can result in very difficult technical problems. Often times, we do things again and again the way they have always been done - because that’s the way that they have always been done. But we can make improvements now that we know [new techniques]. For example, Neoprene gaskets are a good example of what technology is there.

Didi Pei: At the Ronald Reagan UCLA Medical Center, we have an exterior wall made of stone - which you don’t usually see for a hospital. It is one of the most severe seismic areas in the U.S., and that wall had to be able to withstand movement. In California, it is referred to as an “Essential Building,” according to the building codes, which means that in the event of an earthquake, the building not only has to stay standing, but it has to stay entirely functional. So, the wall had to be able to completely withstand that kind of movement. That was a challenge in itself.

SW: What are some current projects that you are working on?

Sandi Pei: The one that I am currently working on that has the most stone is The Centurion on 56th Street just west of 5th Avenue [in New York City]. Stone is not ready to go up on the wall yet, but in about seven months, it should be finished. It’s going to be a very nice building. The exterior will be fully clad in hand-set French “Chamesson” limestone, and it will feature a dynamic stepped profile consisting of a succession of cascading terraces.

Didi Pei: Almost all of our projects have stone somewhere - whether it is in the building wall itself, or in the paving, or on the floors in the lobby. I don’t see how you can build a building today without having some stone somewhere. People say, “Oh, stone is just for the wall.” But it’s not. There are so many other places that you can put stone. So, we always try to find the appropriate material for the right place.

We are doing projects in China. We have a project in Fredericksburg, VA, The United States National Slavery Museum, which is going to be a stone building. The Chinese Embassy in Washington, DC, which is presently under construction, is a stone building. That building, for example, is Italian travertine, but we had to find a quarry that would sell the blocks to be cut to size in China. Not every quarry is going to sell their blocks. That was another complication. When we were starting to source out the material, we had to consider that as well.