Metal is now more than just a building tool, it's become an architectural design choice.

Today, metal as a surfacing material for architectural projects is more an initial-design material than simply an acceptable substitute. Metal can be shaped, folded, polished and colored in forms to which no other material can compare.

Add to this the long-term performance, ability to texture, polish and finish, pleasing weathering characteristics and you arrive at a material palette unsurpassed.

Metal has become the design material of choice for many architects. On some structures metal is the defining feature of the building's facade. Metal, as a design surface, is particularly vulnerable to aesthetic defects and aberrations of construction and manufacture.

It is not so much that metals are softer than other cladding materials; next to diamonds, metals make up some rather tough substances. It is simply that metals are more reflective than other materials and thus minor deflections and scratches are accentuated. "Oil-canning," defined as unstable stresses in flat-plate diaphragms, is a inherit defect associated with sheet metal used in architectural applications.

Thin copper surfaces, when first installed, appear as if someone has been playing basketball on them. As the copper ages and darkens, the reflective surface disappears and so do the distortions. However, when first seen by the customer, panic often sets in. Every detail now is under scrutiny. Convincing them to wait and see is not so easy. Things are now very subjective.

The Museum of Glass in Tacoma, Wash., is covered in shingle panels specially shaped to fit the cone. Photo courtesy of A. Zahner Co.

The awkward stage

Many customers do not understand the way metal will move and change with time. They see an aged roof and this is what they want. And they want it now. They would prefer to skip the adolescent period (as would most parents) and get right to the mature, unchanging stage of the metal surface. No surprises.

Fabricators and constructors of metal surfaces add or take away from the quality of the finished product. They create a large part of the final shape of the building and affect how the building is perceived. This is a burden architectural-metal contractors carry. They are the sculpting tools of the artist. They are expected to have the necessary knowledge and skills to achieve what the designer has created. They have no excuses.

With architectural metal surfaces, the details are where the time and money goes. Success and failure are determined by how the details, the edges and seams, are addressed. First, you have to be allotted the necessary time to achieve the custom edge or finish work. But a clear understanding of the materials - and what is to be expected of them - is necessary.

Metal surfaces take on a level of sharpness, an appearance demanded by the nature of the material. This sharpness is relative to the metal being used. Some metals, such as stainless steel, titanium and steel can have a very straight, unwavering edge. Other metals such as copper, zinc and lead will have a softer edge appearance. Their low-reflective surfaces do not show the undulations, compared with stainless steel and aluminum, where wavering edges can destroy the appearance of the finish surface. Even when the edge is hemmed over, the distinct hard or soft appearance is apparent.

This building on the campus of Bard College in Annandale-on-Hudson, N.Y., is covered in a 16-gauge, exposed-fastener, stainless steel panel. It also has an angel hair finish. Photo courtesy of A. Zahner Co.

Defining details

Correctly constructed edges and seams are the defining details of a surface. Regardless of the quality of the material or finish, edges that are wavy and misaligned will have dramatic effects on the opinion of the quality.

With metal, the edge can occur in the form of individual panel seams within the body of the surface, or it can be a transition between surface planes or materials, or simply the termination point of the surface itself. In all cases, the edge must perform similar to the main body of the metal. It must control moisture and air, allow thermal changes to occur, seismic movements must not be restricted and wind pressures must be resisted and transferred back to the main structure of the building.

These functional characteristics must also withstand the rigors of time. Expectations for the edges and seams of a metal surface are the same as those of the metal itself. Proper detailing and construction is demanded if the results are to be successful.

A recent article in the New York Times describes construction in America, for the most part, as being shoddy and lacking concern for quality. The writer compared construction expectations in Europe and Japan to the United States. What is acceptable in the United States is not acceptable in Europe. The premise is that people in the United States lower their expectations.

The article described the "typical" American approach to seams and edges that do not align properly is to fill them with sealant.

For the Chicago Millennium Park, 110,000 square feet of 22-gauge stainless steel was used. An “angel hair” finish was applied to the steel. Photo courtesy of A. Zahner Co.

Building with bandages

With metal, the solution is often a "bandage" or covering to conceal the edge transitions. These "Band-Aids" are folded metal covers that usually have little or no relationship to the general body of the metal surface. They are simple and cheap solutions that take away from the sculptural beauty metal can provide.

It is not a simple task to custom fabricate metal to degrees of accuracy the eye cannot discern. It takes skill and know-how. Metals used in architecture are very unforgiving and expensive. Hurried work can be costly. However, when performed correctly, the result is nothing short of elegant.

In creating surfaces from metal, the edges are often problematic because they are the most visible. Creating edges of metal surfaces that possess the same moisture-deterrence qualities, the same flexibility and the same appearance without looking patchy or covered with bulky flashing will go miles in providing a high-quality appearance.

Perhaps one of the most difficult aspects to architectural metal work is that there are no real standards. Much of what is created falls in a subjective realm. What is the best from one source is considered marginal from another.

From the article in the New York Times, it is obvious the bar needs to be raised in construction in general. The architectural-metal industry needs to upgrade its approach to constructing the metal surfaces they are providing to our customers.

To achieve this, the industry needs better training for its workers. Constructing mock-ups of assemblies helps in several ways. It requires a demonstration of knowledge, technique and abilities. Once accepted, the mock-up can become an objective demonstration of the requirements of the project.

The industry needs improved quality from material suppliers. Chatter marks, coil stops, edge wave and other inherent defects may be acceptable in the HVAC or industrial sheet metal industries, but will ruin the appearance of an architectural project. Suppliers of stainless steel, titanium, copper and aluminum sheet must improve their quality or superior suppliers from Europe and Asia will replace them.

The industry must manage its customers' expectations. It must be given proper time to produce the final custom product. It needs to educate the customer on the expectations of the material. But most of all, it must support its products and stand behind the result.