Established as one of Philadelphia's major architectural firms, Bower Lewis Thrower Architects (BLT) was founded in 1961 as Bower and Fradley Architects. Seventeen years later - in 1978 - the firm made a change in partnership and took the name that it still carries today.

BLT has an expansive portfolio which includes a broad range of project types. The scope of its designs include mixed-use, corporate/commercial, hospitality, retail, residential and academic. Each principal plays an integral role in the design and project management of all of the firm's commissions. Among BLT's principals are: John A. Bower, Jr. FAIA; John E. Thrower AIA; Arthur W. Jones AIA; Michael L. Prifti AIA; and Eric M. Rahe AIA.

To date, BLT has completed designs of more than 5,000 hotel units as well as a full range of conference and support facilities. These projects range from intimately scaled inns, extended stay and suites-type operations to full-service business and convention hotels such as the Loews Philadelphia Hotel and the Philadelphia Marriott. Additionally, BLT has done work

for entertainment establishments, including Harrah's Atlantic City casino/hotel and the Borgata - a new 2,000-room venture of Boyd Gaming/Mirage Resorts.

Office design also comprises a large amount of the firm's work - with nearly 4 million square feet of space either completed or in construction as well as an equal amount of space planned for future development. Included in this work are both headquarters and operational facilities for a variety of corporations, institutions and government agencies. BLT has further designed numerous speculative and build-to-suit office buildings for developers.

For its work in mixed-use develop-ment, Bower Lewis Thrower has received national attention and numerous awards for Princeton Forrestal Village, a 67-acre parcel owned by Princeton University. This complex includes new retailing, office, entertainment and hospitality services in a town-like environment. The firm has also built continuing relation-ships with prestigious educational and cultural institutions such as the University of Pennsylvania and the Baltimore Museum of Art. BLT's work at Penn includes the Wharton Business School's award-winning Vance Hall, renovations to the Van Pelt Library and the Medical School's new state-of-the-art Stellar-Chance Laboratory Building.

Recently, Stone World sat down with several architects from BLT to discuss some of their current projects that have used stone as well as issues related to the stone industry. The participants in this roundtable discussion include:

  • Kevin W. Aires AIA
  • Victor C. Antes AIA, Director of Interior Design
  • Michael L. Prifti AIA, Principal
  • Roderick H. Wolfson AIA, Associate
  • Michael R. Ytterberg AIA, Associate

SW: Describe the type of work you do.

Wolfson: Our firm is unusual in that we maintain a much broader selection of projects than most other firms our size. We have both a large commercial practice as well as a large institutional practice featuring renovation, historic preservation as well as new con-struction. So we're active in quite a few different markets. I think, as you can see, we often use stone. I direct a lot of the institutional work, and it's often rubble fieldstone used, given the context of the Mid-Atlantic region. Cut stone is specified more for the commercial projects, which have a higher budget.

SW: How do you go about deciding if you are going to use stone and what type of stone you are going to use?

Antes: For interiors, natural stone is very important in terms of defining the quality or enhancing the space, and we use stone a great deal. One of the things I tell my interior designers is that there are three important components in defining the quality of the space. One is floor material, because, immediately, when you walk into a space, whatever that floor material is sets the whole tone and character. Another important aspect is lighting; it doesn't matter what's happening if the lighting isn't good. And, finally, there is the furniture. The furniture defines the space.

In all of our buildings you'll see lobbies. Thus, an important question becomes, what do you put on the floor? We start with natural stone. We like to use natural stone in the lobbies of our space. And then we have to decide if we are talking about 1 1/4-inch material or possibly thinset. And to what extent can we do it? What is our budget? Immediately, that establishes the character of the space. We're talking about all sorts of projects. It doesn't matter if it is hospitality or office or something else entirely. We use stone to set the character in terms of the floor.

We recently completed a job in Chicago that was very high end. We used some blue stone as insets in the millwork. You can't afford to put it on the floor, or elsewhere, but you can buy little squares of it and use it like that. It's a great stone with a lot of variety. And the fact is there is more variety in stone than what the average designer knows about.

Ytterberg: I think the work of the firm is highly context-sensitive as well as obviously client-sensitive. While our work is regionally focused, the firm also works along the Atlantic Coast reaching as far north as Boston and south to the Carolinas. As Roderick [Wolfson] pointed out, though, we frequently choose local fieldstone - Media schist, which comes from a quarry in Media, [PA], and presumably other places. You can find it in most buildings in Philadelphia and the surrounding region, and it's in our work as well.

SW: Does the schist that you are finding now match well with what is on some of the historic buildings?

Wolfson: I think given what we have seen, we have been very pleased with the matches masons have been able to come up with. At the Penn Charter School, which is going to be a new middle school from the ground up, the selected stone is going to match the campus' Wissahickon schist. There we have some concerns about [the fact that there is] only one quarrier.

Aires: Right. There was a case where the client insisted that it be stone because the whole campus is Wissahickon schist. We had just finished a preliminary bidding and I had an alternative quarry call to ask to submit their granite, which they claimed had somewhat of a mica content. They tell me there is only one quarry in the area left that does this, the one in Media in the Delaware Valley. So I guess there is another quarry out there that makes something they think is similar, but we haven't seen it yet. I know it was used on some projects at St. John's and St. Joseph's [Universities] and some others.

SW: That was going to be my next question. There is a large vein of that material that runs into Maryland as well. I was wondering if you used any Maryland schist or is that too different?

Ytterberg: That might be something to consider in the future, for reasons that Kevin [Aires] mentioned. But I think historically speaking, stone has not been expensive. Local products tend not to be expensive, and traditionally it's not a problem.

SW: How often do you visit the quarries?

Ytterberg: It just depends. With the Wissahickon schist, there isn't a lot of reason to go every time. On the other hand, everyone is always eager to do a trip to Italy.

Wolfson: I think that at least with the institutional clients and the institutional fieldstone, we tend to rely on the masons. It's been sufficient to put out a specification that says, "Here's the existing building. Match it and have mock-ups and field reviews." Partially, it's budget-driven. The client's budget for professional services isn't going to have us visiting different quarries in the design stage, but it seems to work in the industry. Masons are able to bring stone to the site, and it is a good match. We don't have a lot of quibbles about how it doesn't match. It's worked out well. It's an interesting aspect of the relationship that there is some trust there.

SW: When working with stone do you find it difficult or easy to find good stone masons to work with?

Wolfson: I guess I'd say both. Surprisingly, we have used stone on a number of institutional buildings, and most of the time the general contractor has come up with a mason that really knows their craft, and we are really pleased. They seem to be really looking out for the long-term benefit of the building. So I'd say generally, there's not only one or two in town, who, if you don't get them you're stuck. There are all kinds of people I've never heard of who are doing good work. We do see bad [masonry work] - particularly pointing and grout work - both things we inherit from other projects, but also it is something we police in terms of mock-up panels. It takes some pushing to say we don't want the mortar smeared all over the stone face, or we have to say, "Look at how the old one had a ribbon joint. That's what we want here," and, "Don't dig deep grooves where water is going to catch." So we do have to police that sort of thing.

SW: Is there a certain qualification process before the masons bid?

Wolfson: I think that it is on the general contractor's shoulders. The general contractor is the one that has to "deliver the goods," so they take the burden of who they're going to trust or who is going to stick them with a big headache.

Ytterberg: I think, again, because of the local area, there are a lot of very good masons. And of course it seems silly, but it's true, they are mostly Italian - in that the Italians have been masons since the Middle Ages, and they all came out of Northern Italy and spread across to Europe and then came to this country. And I don't know how it is possible, but after almost 1,000 years later, all of the major masonry firms are still run by Italians, and they are still doing really great work.

SW: How would you compare working with the stone industry to other industries such as wood or carpet?

Ytterberg: I think that stone is so much more specific to its source, unlike virtually any other product. Whereas with other products, lots of people can supply the material, stone is practically the only product where you can only get it from one place, generally. Sometimes there is another quarry that has something that might work, but it is never exactly the same. So that makes working with stone very unique. Even in this day and age of industrialized processes and interchangeable things, it's still something that reminds you of what it used to be like years ago.

For our purposes, stone has inherently conservative attitudes about it. You tend to use the material that you are familiar with and is locally available. It speaks to values of stability, with people's notions of stone and why they want to use it in the first place. It is very expensive, so it is sort of immune to the forces of fashion, because you can't come up with a new product, flood the market, and then the following year, move on to the next style or variety. It's always the same stone. It would be a weakness to market stone in the context of an ever-changing, fashion-driven kind of design industry. The very reason people want it is because of its permanent set of values and the very real sense of maintenance-free and long-term life span - all these pluses stone brings to us.

Antes: It's interesting though, there are standards and certain marbles and stones that one uses. But then there are some exotic stones out there - not as well known - which have a great beauty to them. You have to be running in a certain crowd to find out they exist and what the price range is going to be. There's non-standard "stuff" out there, for instance, German stones and so on, that have multi-colors and look like green slates. There are some very nice things to choose from.

The problem with that is when you go to specify it. We have a job we're completing now for a law firm in Boston. We were looking at some limestone and a bluish slate; the client was sensitive to the price. We we're also working remotely so they found us a supplier¿$30 a square foot for a blue slate. They blew us out of the water. In terms of material, we're talking about spending maybe $7 or $10 - not $30. My client wasn't interested.

Wolfson: And I think how you specify it is a difficult thing, particularly with historic projects where you're matching marble and granite. We really rely on the stone architectural reps, and they are very helpful in going out to the site and finding the marble that matches what we're working on. Here in Center City, we're working with a pink marble in Suburban Station - the main train station that was built in the 1920s. There's cream and pink marble to match as well as some 1960s granite. One of the sales reps was really helpful in getting us samples to base our specification on. The flooring there is terrazzo, but the pink marble is trim on the columns.

Aires: We also need to ask for bigger mock-up samples for certain stone materials that have a mottled look across them. At least with the [Penn Charter] school, I noticed it is not just one stone color. There are dozens. And the same applies for the slate.

Wolfson: Yes, we're trying for a slate roof there to match the existing one.

Aires: It's not just a gray roof. It has pinks and grays mixed together. So there you need a much bigger mock-up to see all of the colors.

Ytterberg: I think that highlights a good point. If there is any single stone type that ends up on the exterior of our buildings, because so much of it exists in the area, it's Wissahickon schist. But for the interior of the buildings, we obviously want to see a tremendous variety of stone types. And because a large percentage of our projects are historical/adaptive reuse projects, we face a situation of matching what was removed. We're working on a building right now that uses Mankota stone. So there is a much greater range of sources there. But again, it makes it specific. You have to go back to that quarry.

Wolfson: We designed a science addition for the Baldwin School. It was a 1960s building - fieldstone with Kasota spandrel panels - and we needed to add one more base. We wanted to match the Kasota stone, and the contractor went back to the same quarry, but because they were digging at a deeper place, the stone wasn't an exact match.

Antes: For one of our projects, a high-end residential project named the Phoenix, we have a retail atrium featuring a lot of natural stone. Some of the stone throughout is interesting, Tennessee Pink marble, for example, which is very prevalent throughout our area. It can be a typical stone to work with because of its coloration and so on, but the neat thing about it is that it is harder than marble and a little softer than granite. So we use that generously. Another interesting stone in the building is Kasota stone - sort of a yellow marble that you don't see quite as much of, but these are things that create the character of the building. Also, there is a lot of [Vermont] Verde Antique marble. It's interesting to see how stone was used back then, and how we try to use it now. One plus with certain renovations is, what you have to work with, existing materials, is a lot better than what you might be able to afford new.

So for this building, which has all of the Tennessee marble, etc., with very nice inlays, we say, "Can we do the retail atrium in Tennessee marble?" And [the owner] says no. So then you ask, "Can we use Kasota marble in that atrium?" And again, the answer is no. The question then is, how do you create that feeling? There, we are actually using other natural stones to try to keep the continuity. We are using five different colors, ranging from a cream to a salmon type. And that's what is nice about stone. The stones are great when you look at the character of them. There are a large number of varieties and types available. The problem, we as designers have, is if you go to our resource library, you either find small samples or larger ones that are deceiving in terms of the overall character.

SW: When looking for new stone, do you look for new sources often or do you refer to the same library of stone?

Antes: The library is pretty static because there aren't a lot of stone vendors out there to keep the library updated. It's not like ceramic tile reps. The [stone reps] are sort of "old country." They work with the quarries. When you are talking stone, they're looking for big corporate headquarters that will use a lot of material. They're not interested in small jobs. It just doesn't make sense for them. And even though we are doing a lot of bigger projects, establishing a relationship with someone who has a quarry, who has a sample, who is interested in doing the sample and getting them to you, is often difficult.

SW: For your residential work, how do you go about selecting stone?

Ytterberg: I recently completed a residential custom project that adheres to a lot of issues we are talking about. This is a pool addition to an existing home. The home already featured traditional local stone, so we matched what was existing. The exterior decks and the interior around the pool is all slate. Again, it continued what was already in use around the house. The pool and guest wing doubled the size of the house, including extensive slate exterior decks continuing around the pool. The walls are all Wissahickon schist. In some areas, such as the bathroom and guest suite, there are some decorative uses of tile. The tile was available through a supplier of tile products as opposed to a quarrier.

But again, there was an Italian mason involved with this who did fabulous work in terms of the sharpness. There are various places where there were oddball angles in the plan for the stonework, and the masons did a fabulous job. The only negative was that we found one stone to form the lintel on the upper fireplace, but gave up looking for the stone to form the lintel on the lower fireplace.

SW: How do you look for a huge stone like that?

Ytterberg: You go to the quarry and poke around. I suppose we probably could have had it cut and shaped, but it was decided against at that point.

SW: When you use a schist or fieldstone, what are the sizes of the pieces, and how is it put up? Is it sliced on the back and used as a veneer, or do you use full-size pieces?

Wolfson: Generally, it is 6 or 8 inches thick. One project - a church we completed in Devon - started with the presumption that 4 inches would be more cost effective. But we discovered a lot more cutting would be involved to get 4 inches; with 6 or 8 inches, they simply put it up.

SW: For your new construction, would you say that Bower Lewis Thrower has a specific design style or is it more of a general philosophy?

Wolfson: I think our philosophy is to not have a specific style.

Ytterberg: Well, we have a philosophy that is to be responsive to the client, context and the other issues involved around any particular project. Certainly, this is related to largely the fact that 30 to 40% of our work is adaptive reuse and additions/renovations to existing buildings. Even taking that as a subset of our work, there is no single approach. For one project, Trinity Evangelical Lutheran Church, we have a building where there is an existing nave, and it was enlarged by an addition of a transept across the nave to create a traditional cross-shaped plan, where the architecture of the transept matches the nave absolutely. You just cannot tell that anything was ever different. On the other hand, we have projects such as an addition at the Bryn Mawr College Campus Center where the Wissahickon schist continues throughout, but the details that blend with the existing building don't mimic it exactly.

Wolfson: It clearly is a modern building.

Ytterberg: It's an interpretation. We have other examples where additions are even further away from the existing building. So even within that narrow range of adding to an existing building, it is not a one-size-fits-all solution. It depends upon the desires of the client and the needs of the project and all sorts of other issues. I wouldn't characterize the philosophy as being completely pragmatic; it definitely goes beyond that point.

Aires: I think it varies for the type of client we're talking about, too. I know at the Penn Charter school, it's a Quaker institution, so there's a strong commitment to consensus building with a lot of input from the faculty all the way up to the administration. In this case, we're not only trying to be responsive to one user. In other cases, you do have just one [user].

Wolfson: At Penn Charter, we had a great dialogue regarding what the new middle school should look like. The original building on campus is a 1920s style. There are some '60s and '70s structures that have the right stone, but there is no sympathy with the architecture otherwise. So we engaged in a dialogue.

Aires: The existing building has a large tower and a very consistent facade. Our addition is a separate building. We're keeping with the traditional materials of stone and slate, but also looking to larger window openings and more modern detailing.

SW: When you are working on a project like this, where the representatives of the school and everyone else is involved, is it hard to get everyone on the same page in terms of what you are going to do in the design?

Aires: Sometimes you have to get people to focus on what the question is at hand because everyone has their own agenda and concerns. And when you bring in neighbors, which is something that a school like this wants to do, they obviously have a perspective as to what is important. Usually one can get a focus on what the specific question at hand is. For instance, "How wide does a window need to be?" That generates talk about what type of opening and how you are going to deal with the stone involved.

Wolfson: It takes a lot of drawing on our part to communicate. We're trained to think visually, which is often hard for lay people. You want them to get a full understanding so they are empowered to make decisions. We find the challenge is to "draw" the right things so the participants are actually "picturing it."

Aires: We've started to use a lot more color in our renderings, which I think helps the client understand, but at the same time it's very hard to be literal with colors. So what we like to do is bring samples in, and with the stone, they have it right there on campus so it's not a problem.

Wolfson: And once we go to three dimensions, it helps them.

SW: In a case like the Penn Charter school, does the client look at mock-ups, or is that more for your own use?

Wolfson: Typically they are in on that. It just depends on personalities, and how much they have a set opinion verses deferring to their consultant. We want to hear what their gut reaction is. If they are concerned or unsure whether something is going to look good, we want to pursue it until there is a comfort level.

The affordability issue of slate is something we keep bumping into. The Penn Charter slate is multi-colored, and the thickness of it is really beautiful. At the Baldwin School's main building, which was designed by Frank Furness, the whole roof was all red slate. A little bit is remaining on the vertical. In fact, we had to salvage some from the main roof in order to finish and restore the arches.

At Baldwin, we explained that the original roof was red slate and indicated what it would cost to do more with that material. It was at least twice the price of asphalt shingles, and as asphalt shingles climb in life to 40 years, it's hard to get clients to make an initial investment with slate.

SW: What are some other recent projects that your firm is working on?

Prifti: I'm serving as Principal-in-Charge, with BLT Associate Mark C. Wieand AIA as Project Manager, for two labs we're designing [in joint venture with Payette Architects] at Penn State University, State College, PA. There is a $45 million Chemistry Building and a $34 million Life Sciences laboratory that are linked across the quadrant. It is very exciting. They are mostly brick, but there is limestone and granite trim at the base to make for traditional campus architecture, as they have in the adjoining buildings there. It is not a predominant use of stone.

SW: What type of limestone and granite?

Prifti: Whatever is to match. Basically, it is a contextual issue there, and so everything is to be sympathetic to the campus - rather elements of the campus. They use three different brick colors, and we're picking one of the three. The same applies for the stone. They use a lot of indigenous stone and then some that is brought in.

SW: Is the project just starting?

Prifti: The Chemistry Building documents are finishing up, for the Department of General Services, which follow a protocol where the Common-wealth is the client. The other building, Life Sciences, is a direct commission by Penn State. So it is really interesting. We have two very similar user groups, and two buildings that are very similar in appearance, but we have two dissimilar clients and two methods of procurement and construction. We're going to have our hands full. Life Sciences documents should be finished up by late May or June.