東京都内の新興住宅地に建つ、一戸建ての住宅である。敷地は北向き、かつ3階建ての住宅に囲まれており、日照面からすると決して恵まれた条件とはいえない。一方で建主は「ヨガができる日当りの良いテラス」を希望されており、これを実現するため家並みが途切れて唯一日照のある敷地東半分の2階にテラスを配置して、十分な明るさのある屋外空間をまず確保することにした。ここに南北方向へ大きく貫通するスペースをつくることで風通しの良さと開放感を得ながら、東西方向には壁を設けることで隣家の窓からの視線を遮断している。
このテラスに屋根をかけて居間や寝室と行き来のできるテラス窓で接続することで、この場所を屋外空間として楽しめるだけでなく、屋内空間にとっても採光や通風に有用な緩衝空間とすることが可能になる。この空間は大きければ大きいほどたくさんの青空をつかまえることができ、日照にも恵まれることになるが、一方で限られた建築面積の中でテラスを大きく確保するという選択は、そのぶんだけ居室の床面積を奪ってしまうという結果にもつながりかねない。
そこで1階と2階の間に天井の低い収納階を挿入し、居間や寝室から収納などを減らすことで可能なかぎり広い居室面積を確保して、屋内空間の減少を補うことにした。天井高1.4m以下であれば収納階は法規上の階数に含まれず、3階建ての法的制限を超えることなく実質的に建物の床面積を増やすことが可能になる。また、収納階が挿入されたことで2階のテラスと居間の床レベルが半階分押し上げられ、両空間の日照がさらに改善されると同時に、隣家の窓と高低差が生じたことで外部からの視線と干渉の起こりにくい状態がつくり出されている。(山本卓郎)
A house with a semi-outdoor space on a large terrace that runs from north to south
“Little House with a Big Terrace” is a lucid example of having large external space in small urban residence with limited site area of Tokyo. Through the process of designing this house, we tried to prove that having rich private external space was important for making crucial difference in the quality of life inside the house, as well as obtaining various possibilities of external activity.
The first thing we decided was having an open-air space next to the main part of the residence and connecting them with a big opening of windows. Big Windows, which are necessary for making internal spaces spacious, well-lighted and airy, is one of the most costly parts of buildings, so we concentrated them to selected places, effective for improving the quality of internal spaces. Considering that the client couple’s original request had a big terrace for doing yoga freely under the sun, connecting the terrace to the living room and the bedroom with big windows was the best way to offer fresh air and daylight to the internal spaces, like having respiratory organ to let the house breathe.
The second-floor level of the eastern half of the site was chosen as a private open-air space, because that place was facing to the rooftop of the single-story garage of a neighboring house on the south. Thanks to the lower height of the garage, this place is exposed to the sunlight in the high-density residential area, which is a relatively rare situation in Tokyo. By making a big rectangular tube here penetrating north-south, a bright and airy open space can be obtained. At the same time, the privacy of this external space is protected against very close windows of neighboring houses on the east, by the wall of the tube closed to that direction.
The tube was tried to be made as large as possible, because larger external space can catch more sunshine and larger blue sky. However, having large external space in the limited site area means a reduction of the internal space of the house. To make up for the loss of the floor area, an attic for storage was inserted between the first floor and the second, whose ceiling height is less than 1400 mm. By this arrangement, this house obtained a sufficient amount of practicable space while the daylighting of the living room and terrace was improved, because the levels of those spaces were pushed up higher.
As you have already seen, “Little House with a Big Terrace” creates comfortable internal spaces by connecting them to the unlimited extension of external space. The most effective way to achieve real spaciousness of urban houses in a high-density residential area is to incorporate unlimited external spaces into the design rather than trying to make internal spaces larger, which is inevitably limited by the size of the site area. (Takuro Yamamoto)
【大きなテラスの小さな家】
所在地:東京都江戸川区
用途:戸建住宅
クライアント:個人
竣工:2015年
設計:山本卓郎建築設計事務所
担当:山本卓郎、森田遥
構造設計:山田憲明、林弘倫(山田憲明構造設計事務所)
家具制作:田中工藝
施工:山中丈大(山庄建設)
撮影:新建築写真部、中村絵(中村絵写真事務所)、山本卓郎建築設計事務所
工事種別:新築
構造:木造
規模:地上3階
敷地面積:70.13m²
建築面積:41.91m²
延床面積:74.63m²
設計期間:2013.02-2014.08
施工期間:2014.09-2015.04
【Little House with a Big Terrace】
Location: Edogawa-ku, Tokyo, Japan
Principal use: Residential
Client: Individual
Completion: 2015
Architects: Takuro Yamamoto Architects
Design team: Takuro Yamamoto, Haruka Morita
Structure engineer: Noriaki Yamada, Hiromichi Hayashi / Yamada Noriaki Structural design office
Furniture production: Tanaka Kogei
Contractor: Takehiro Yamanaka / Yamasho Kensetsu
Photographs: Shinkenchiku-sha, KAI NAKAMURA / KAI NAKAMURA PHOTOGRAPHY, Takuro Yamamoto Architects
Construction type: New building
Main structure: Wood
Building scale: 2 stories
Site area: 70.13m²
Building area: 41.91m²
Total floor area: 74.63m²
Design term: 2013.02-2014.08
Construction term: 2014.09-2015.04