Dumping steel

When it comes to commercial construction, New England is steel country. Other parts of the country favor concrete, which is more expensive, but here almost all modern towers and tall residential buildings are built on skeletons of steel columns and beams.

But with construction costs skyrocketing, due largely to the rising price of steel, the developers of a new luxury condominium in Providence that will be Rhode Island's tallest building scrapped plans for a steel structure and drew up a new design for concrete. As a result, Blue Chip Properties LLC squeezed two extra floors into a building that didn't need to be any taller.

``The steel price rises day to day," said Minhaj Kirmani, a principal of Weidlinger Associates Inc. of Cambridge, consulting engineers to Blue Chip Properties. ``Nobody can guarantee prices six months down the line."

Though costly, structural concrete has severalsignificant advantages -- including ensuring maximum peaceand quiet in high-priced, high-rise homes. ``You really are looking for as quiet as you can be," said Gary C. Johnson, a principal at Cambridge Seven Associates Inc., the architectural firm on the project.

Besides making the engineering details work, developers have to make the financial numbers add up, and escalating construction costs have presented a huge challenge lately.

Jeffrey A. Gouveia Jr., executive vice president and general manager of Suffolk Construction Co. of Boston, said profit margins on some projects have become so narrow that developers have abandoned them. ``The economics of the projects just don't work," he said.

Others have found ways to trim costs.

On One Ten Westminster, it was swapping steel for concrete.

Even with steel prices on an up elevator, switching to concrete was more expensive foot for foot than steel. ``But the delta" -- that's contractor talk for the price difference -- ``got small enough that we thought the advantages were strong enough to do it," said Jeremiah O'Connor III, project manager for Blue Chip.

At 435 feet, One Ten Westminster will be the same height as if made of structural steel, and from a distance it will look almost identical to what was originally planned. But a few key details will vary: In the new, concrete version, it will be 38 floors instead of 36. Floor-to-floor heights are several inches less in concrete, even though ceilings in finished units are at least as high.

There will be an additional floor of condos and another floor of above ground parking, with one basement level eliminated. That means eight more units to sell, and several million dollars of additional revenue. And it avoids excavation, which was both expensive and sensitive, given the project's proximity to historic buildings.

Those two advantages, plus an engineer's notebook full of less dramatic factors that the development team says favor concrete over steel, mean that despite today's soaring cost of construction the building will get under way in a few weeks, with concrete trucks' bins whirling.

Steel industry representatives bristle at suggestions that concrete is superior. ``In a 38-story building, we can knock four months off your construction schedule," said Robert W. Pyle, a regional representative of the American Institution of Steel Construction Inc., an industry group.

But in certain situations, concrete is preferred. Developer Dean F. Stratouly built Museum Towers apartments in East Cambridge out of concrete in the late 1990s for many of the same reasons it is being used in Providence. ``They're a better residential building when they're concrete," he said.

A concrete building is composed of concrete columns and floors and a core of concrete walls, surrounding elevators and utility shafts in the center; but exterior walls and most walls within the residential units are -- same as in a steel building -- made mostly of sheets of drywall.

The One Ten Westminster project's construction start was delayed by four months while concrete was substituted for steel in the design. ``We dumped an entire set of drawings that we re steel right in the toilet, and that wasn't a pleasant process," said Eamon C. O'Marah, managing partner of Blue Chip. ``But we ended up with a better building."

Construction prices have risen about 20 percent since the beginning of 2004, and the cost of steel -- driven up by fierce demand for steel from China and the other emerging economies of Asia -- is one of the major reasons.

The price of steel is based largely on the cost of scrap metal, which gets recycled into the beams that form modern buildings. That price has gone up about 70 percent since late 2003, meaning a typical ton of finished steel that cost $380 two-and-a-half years ago now costs $660.

Even a concrete building requires some structural steel, known as rebar, to give it strength. But that amounts to only about half of the steel that is used in a steel frame. Rebar is cheaper than steel used in structural beams, and doesn't have to be fabricated into precise shapes and sizes, which with energy prices also rising is increasingly expensive.

One cost saving inherent in using concrete involves how much ``crane time" is needed to assemble a building. Each steel column or beam placed in a steel-structured building is a separate ``pick" by a crane. Tower cranes cost about $50,000 a month to rent, adding a lot to the total cost of construction.

In addition to getting two more floors into a building of the same height with concrete, other factors favored getting away from steel, according to the architects and engineers:

Walls in the units are easier to move if buyers want to customize their units. And the number of internal columns is reduced, so views and rooms are less likely to be obstructed.

Floors and ceilings made out of concrete cost less to fireproof, and steel structures require expensive false ceilings that hide the beams themselves.

Exterior windows and glass and metal panels are easier to hang on concrete than on steel beams.

Cambridge Seven Associates spent months designing and planning a steel building, with a modern glass-and-steel skin. Weidlinger Associates worked months on the engineering, coordinating with Suffolk Construction on prices and construction timetable issues. And the cost of all those professional services increased because of the additional work in going from steel to concrete.

But that wasn't all.

A detailed 6-foot-high model of the building, and a historic market building structure on the downtown Providence site that will be preserved as part of the project, was nearly complete months ago. But then came the switch to concrete.

Though the visual differences are subtle, Blue Chip ordered the artist to start over and make a new $20,000 model.

``It looks the same unless you count the floors," said Gouveia.

Thomas C. Palmer Jr. can be reached at tpalmer@globe.com.