Letters

I read your article in the October 2006 issue on the new Libeskind tower in Sacramento (p. 10), and was amazed by two big inaccuracies.

First, scissor stairs are not novel; they have been used for many years, especially in Europe where they are still in use for multi-story residential buildings. One of my college professors in Warsaw was using it extensively in the late 1980s.

Second, the International Building Code does not permit them to be counted as two separate stairs even if the doors are adequately remote.

IBC 1015.2.1 clearly states: “Interlocking or scissor stairs shall be counted as one exit stairway.” As far as I can remember, no building code in the U.S. has allowed for the use of scissor stairs as two separate stairs for at least the last 15-20 years. Otherwise, all developers would be asking for it to save floor plate space.

Additionally, the City of New York has curtailed the use of scissor stairs for certain commercial projects in response to the World Trade Center attacks because of the danger of having both stairs in a single shaft.

While the construction for the stairway and core for the Libeskind building sounds impressive, it is only “novel” in the fact that they gained approvals for the construction of something that doesn't meet the letter of the code.

I wouldn't want anyone to get the wrong idea.

Lawrence C. Divita, AIA

Davison Smith Certo Architects Inc.

Westlake, Ohio

I normally appreciate the down-to-earth information about architecture and construction that I get from BD+C as a useful adjunct to that of the fad-based journals.

I must comment, though, that the double-stair core featured in the referenced piece is far from novel, in fact having served as a standard dodge for high-rise egress for many years until it became difficult to employ due to changes in building codes. True, the right circulation pattern would render the double stair safe and efficient, but we see no floor plan information upon which to judge in this case.

One can't resist commenting also on the banal appearance of the building as illustrated. I hope that Mr. Libeskind has not suffered the all too common fate of architects finding rapid commercial success following an extended life in the conceptual realm, that of consenting to a cursory design phase and debasement thereof by the client and architect of record.

Kenneth M. Moffett, AIA

Bullock, Smith & Partners Inc.

Knoxville, Tenn.

Your article noting, “Novel double-stair core…” is a bit late.

The architectural firm I worked for in New Orleans, Stanley Muller and Associates, used that stair design more than 30 years ago. We had the task of proving to the permit department that the two stairwells were totally separate. We had a contractor build a four-story mock-up and flood one side with smoke. The building officials and fire marshal were convinced and we started using that stair design on a majority of our high-rise designs.

Robert E. Neal, AIA

Baptist Health Systems Inc.

Jackson, Miss.

I read your “Glazed Brick Primer” in the November issue (p. 79) with great interest and wanted to offer some comments on your flashing details.

Two of the wall section drawings show the flashing inserted into the mortar joint of the concrete block back-up wall. While I agree that this is an excellent installation method, it comes with a very high degree of risk. This age-old detail was born in a time when the concrete block back-up and brick fascia went up concurrently.

Today, we typically raise the back-up to its full height and return, sometimes weeks or months later, to raise the fascia. This leaves the flashing in harm's way for extended periods of time and all too often results in a severely damaged flashing membrane. Picture, if you will, the flashing hanging from that mortar joint over a third-story window during a thunderstorm. We typically get a call the next day asking for instructions on how to repair or replace it. York recommends that you avoid this detail and hang the flashing with a termination bar the same day that you install the fascia and eliminate this installation risk all together.

In addition, your first detail drawing shows a coping stone on a parapet set in a slurry of mortar above the flashing membrane. When this flashing membrane is drawn completely across the top of the block and fascia, as it is shown in the detail drawing, it does not allow any drainage path, because there are no weeps. With this design, you are asking any water that finds the flashing to either go back out the way it came in or, more likely, to wick out through the mortar joint, which is not ideal.

Joe Lincourt

President,

York Manufacturing

Sanford, Maine