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National Diet Library Newsletter

No. 210, February 2017

Rediscovering the Annex Building on its 30th Anniversary

This article is based on the article in Japanese in NDL Monthly Bulletin No. 667 (November 2016).

Rediscovering the Annex Building

<<User’s area of the Annex>>

Completed in 1986, the Annex of the Tokyo Main Library of the National Diet Library (NDL) celebrated its 30th anniversary in 2016. In commemoration of this anniversary, here is an introduction to some of the Annex’s more interesting features together with some rather intriguing pictures taken during its construction. We hope this article will provide an opportunity to rediscover the Annex.

<<The user area at the time the Annex was opened>>

The Annex building is located to the north of the Main building. It is a rectangular building, running east to west, and comprises four floors above ground and eight floors underground.

Perhaps the most distinctive characteristic of the Annex is the gigantic area underground that is devoted to closed stacks. Around the time the Annex opened, the popular quiz "Quiz Omoshiro Seminar," which aired on Nippon Hoso Kyokai (NHK), asked this question: "What is something that is missing from the closed stacks of the NDL?" The answer is restrooms. Even now, the NDL’s closed stacks often appear in magazine articles and TV programs. They are also one of the highlights of a guided tour of the NDL. Recently, there was even a comic series that depicted an imaginary ninth underground floor in the stacks.

We can say this particular fascination derives not only from the fact that the stacks are gigantic but also from their unique function as a repository of all knowledge published in Japan.

From the time it was completed, the Annex’s closed stacks have been a repository primarily for periodicals and newspapers. In fact, the Annex was designed in accordance with what was the prevalent concept of an information society at the time: the idea that the number of periodicals in publication had increased, and library patrons were keeping abreast of the latest information by reading newspapers and magazines instead of books. And although computer terminals have replaced the card catalogs that once lined the halls of the Annex, many patrons continue to visit the NDL with the same objective: the search for accurate and up-to-date information.

We hope this article provides readers with the opportunity to rediscover the attractions of the Annex building on this, the occasion of its 30th anniversary.

The many features of the Annex



In addition to the closed stacks, the Annex building has a great many other interesting features.

Concrete pillars and wall

<<A concrete pillar imprinted
with a wood texture>>

<<The rough finish surface
of the concrete wall>>

As seen in photo on above left photo, wood texture was applied to the surface of unfinished concrete using a mold made of cedar. Special care was taken in selecting the wood used to make this beautiful pattern. The uneven surfaces on concrete walls inside the building were made by chiseling directly into the surface of the wall by hand.

Atrium and double columns

The entrance to the Annex building comprises an atrium that extends from the first to the fourth floor and bring in natural sunlight through a large skylight. Some of the pillars in front of the reading room are made in a "double column" configuration. Each double column comprises two pillars with a beam that connects them. This technique disperses the bearing weight and provides a high degree of freedom in designing space.

Tiles used in the interior/exterior walls

<<The tiling in the hall in the Annex>>

<<Tiling on the exterior wall facing the garden>>

Large areas of both the interior and exterior walls of the Annex are covered with blue tiles. The deep blue color was achieved only after much trial and error. The tiles are double glazed and baked in a kiln at a temperature of 1,210℃, which is 20–30℃ higher than the standard kiln temperature.

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Photo album of the Annex construction: Back to 1981-1986

<<Construction work of the Annex>>

The construction of the NDL Annex building was a technological challenge, requiring excavation to depths of 30 meters in a limited space and the construction of a water-resistant structure.

Let’s go back through time by looking at these photographs from 30 years ago!

<<The steel rebar cage for the continuous retaining wall>>

First, to facilitate excavation to such an extreme depth in a narrow space, a huge, continuous concrete retaining wall was cast around the building site. This retaining wall around the area to be excavated provided protection against landslides and collapsing soil. It also helped prevent groundwater from infiltrating the excavation site. The photograph above shows the steel rebar cage hoisted with a crane and being lowered into the trench.

<<The main building is on the left side of this photo. The excavation of the Annex area has started.>>

<<The first floor and the first basement floor are constructed.>>

<<As the excavation proceeded to a depth of 30 meters, the excavated soil was raised and transported offsite. During excavation, 30,000 truckloads of excavated soil were carried to the site of the Haneda Airport extension. The reddish steel beam in the photos are temporary structures used to reinforce the retaining wall during excavation. >>

Why are there eight underground levels?

There was a particular reason behind the Annex building being designed to have eight underground levels. This reason had to do with the substantial weight that would be placed on the building once the underground stacks were filled with library materials, which required the entire structure to rest firmly on solid ground. A geological survey found a solid stratum, known as the Tokyo Gravel Layer, at a depth of approximately 26 meters underground. It was determined that eight underground levels were necessary to allow the structure to rest securely on this stratum. In contrast, the height of the Annex aboveground was determined in consideration of its effect on the National Diet, the Supreme Court, and other nearby buildings.

<<The roof of the Annex building is supported by a single 24.6-meter-long steel beam.
The photograph above shows the beam being hoisted into place.>>

<<A worker applies waterproofing to a concrete wall.>>

Waterproofing the structure

Waterproofing the structure was an essential measure for protecting the books in the stacks from moisture. Waterproofing was sprayed on the surface of the continuous retaining wall to a thickness of six millimeters. Next to that was built another concrete wall that formed the building’s foundation, to which a 1.5-mm thick waterproof rubber membrane was applied. Next, an inner wall was constructed 30 centimeters from the foundation, leaving an air space and providing the stacks inside the building with multiple layers of defense against moisture.

<<Construction of the aboveground floors>>

<<The completed Annex Building! >>

(Translated by Tomoaki Hyuga and Mika Oshima)

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