Construction - kenchikusekou

Japanese: 建築施工 - けんちくせこう

The implementation procedure for construction work varies depending on the individual work, but generally, the work is carried out in the following order: planning, design, ordering, cost estimation, bidding, contract, start of construction, construction work, and completion. In general, the process from ordering the work to completion is collectively called construction work.

[Shunichi Maruyama and Jun Takenaka]

Construction implementation method

There are various construction methods, such as the direct method, where the building owner carries out the work by themselves, the contract method, where the building owner enters into a contract with a construction company to carry out the work, and the commission method, where a commissioned contract is used. Currently, most construction work is carried out by the contract method, and the work is usually carried out by three parties: the building owner as the customer, and the architect and construction company who are commissioned by the building owner to carry out the design and construction supervision on their behalf.

Based on the contract, construction companies complete a specified building within the contracted construction period and within the contracted amount. In Japan, construction companies can only operate if they receive permission from the Minister of Land, Infrastructure, Transport and Tourism or the prefectural governor, as stipulated in the Construction Business Act. Sometimes multiple construction companies form a joint venture and work together on a project. It is not uncommon for public institutions and companies to have specialists in design and supervision within their own organizations, and for construction companies to take on construction work, including design.

[Shunichi Maruyama and Jun Takenaka]

Bidding and Contracting

When a building owner submits a work order, the construction company submits a work estimate, and once a contract is concluded between the two parties, work begins. A bidding process occurs when a building owner submits a work order and a contractor submits an estimate for the work. Bidding methods include open competitive bidding, where bidders are publicly invited to compete, and designated competitive bidding, where the building owner nominates multiple bidders. In some cases, instead of bidding, the building owner may enter into a contract with a contractor they deem appropriate after discussing and reviewing the estimate. This is called a discretionary contract. When only one contractor is selected from the beginning and a quote is requested, it is called a special order. There are two methods for ordering work: ordering the entire work as a set, or dividing the work into several parts or types of work and ordering them separately.

A construction contract between a building owner and a construction contractor defines the rights and obligations of both parties regarding the completion of the work and payment of the contract fee, and includes the contents of the work, construction period, delivery time, contract fee amount, payment method, and post-completion guarantee. The documents that clarify these contract contents and constitute the contract are called contract documents. Contract documents usually consist of a contract, contract terms, drawings, and specifications. Contract terms are a comprehensive description of general contract contents other than the basic matters stated in the contract. The drawings and specifications are called design documents, and the specifications indicate the conditions of the work, construction methods, accuracy, quality, etc., and clarify the contents of the work together with the drawings. The parties to the construction are legally bound by these contract documents, and the work is carried out in accordance with the contract documents.

[Shunichi Maruyama and Jun Takenaka]

Confirmation application procedure

Prior to starting construction, the building owner must complete the confirmation application procedure based on the Building Standards Act and have the building design confirmed by the prefectural or municipal building official or a designated inspection agency designated by the Minister of Land, Infrastructure, Transport and Tourism to determine whether or not the building meets the legal standards. Normally, this application procedure is carried out by an architect delegated by the building owner. The building must also be inspected by the supervisory agency during and after construction is completed, and it may not be used until it has received an inspection certificate from the building official or the designated inspection agency.

[Shunichi Maruyama and Jun Takenaka]

Construction work

A wide variety of construction work is required from the start of construction to completion of a building. In order to complete these works with the required quality and specifications, within the required construction period and contract amount, it is necessary to create detailed construction schedules and construction plans, and to properly manage and operate various items such as safety, environmental conservation, quality, schedule, construction costs, materials, labor, outsourcing, and machinery.

[Shunichi Maruyama and Jun Takenaka]

"Architectural Construction" edited by Yoshiya Uchida (1999, Ichigaya Publishing)" ▽ "Latest Architectural Construction" by Kazuo Koida (1999, Gihodo Publishing)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

建築工事の実施手順は個々の工事により相違するが、一般には企画、設計、発注、積算、入札、契約、着工、工事施工、竣工(しゅんこう)の順序で遂行される。一般には、このうち工事発注から竣工に至る過程を総称して建築施工という。

［丸山俊一・竹中　純］

工事実施方式

建築工事の実施方式には、建築主が自らの手で行う直営方式と、建築主が建設業者と請負契約を結び工事を実施する請負方式、および委任契約による委任方式などがある。現在、建築工事のほとんどは請負方式によって施工され、通常、工事は需要者としての建築主と、建築主の委託を受けて設計・工事監理などを代行する建築家および建設業者の三者で実施される。

　建設業者は、請負契約に基づき、請負金額内で契約工期内に所定の建築物を完成する。日本では、建設業は、建設業法の定めにより国土交通大臣または都道府県知事の許可を受けたものが営業できる。複数の建設業者が共同企業体（ジョイント・ベンチャー）を結成し共同連帯して工事にあたることもある。公共機関や企業が自己の機構のなかに設計・監理などの専門担当者を擁したり、建設業者が設計をも含めて工事を請け負うことも少なくない。

［丸山俊一・竹中　純］

入札と契約

建築主からの工事出件に対し建設業者側が工事見積り金額を提出し、両者間の契約が成立すると工事が着手される。入札とは、建築主側が工事を出件し、請負業者側がその工事の見積り金額を提出することをいう。入札方式には、入札者を公募して競争させる一般競争入札、建築主が複数の入札者を指名する指名競争入札などがある。入札によらず、建築主が適当と思う業者と見積り内容を協議検討して請負契約を結ぶ場合もある。これを随意契約という。最初から1業者のみが選定されて見積りを依頼される場合を特命(とくめい)という。工事発注方式には、工事全体を一式で発注する場合と、工事をいくつかの部分または工種に分けて発注する方式とがある。

　建築主と工事請負業者との間で結ぶ工事請負契約は、工事の完成と請負代金の支払いに関する両当事者の権利と義務を定めるもので、工事の目的物、工期、引渡し時期、請負代金の額、その支払い方法、完成後の保証などの内容について契約する。これらの契約内容を明示し契約を構成する書類を契約書類という。契約書類は通常、契約書、契約約款、図面および仕様書により構成される。契約約款は、契約書に記載された基本的事項以外の一般的な契約内容を網羅して記載したものをいう。図面と仕様書は設計図書とよばれ、仕様書には工事の条件、施工方法、精度、品質などが示され、図面とともに工事の内容を明らかにする。工事当事者はこれらの契約書類によって法的に拘束され、工事は契約書類に従って実施される。

［丸山俊一・竹中　純］

確認申請手続

建築主は、工事着手に先だって、建築基準法に基づく確認申請手続をとり、設計された建物が法令の基準を満足しているか否か、都道府県または市町村の建築主事または国土交通大臣の指定を受けた指定確認検査機関の確認を受ける必要がある。通常この申請手続は、建築主の委任を受けた建築家が代行する。工事の中間および竣工時にも監督官庁の検査を受け、建築主事または指定確認検査機関からの検査済証を交付されて初めてその建築物を使用しうる。

［丸山俊一・竹中　純］