造成と影、対角と光、家と庭

丘陵地の住宅街に計画した家族４人の住宅。敷地は道路から約２ｍの高台に地盤があり北側にだけ接道している。南側も東側も境界間近の隣家に接し、西側も現在は空地だけれど、まとまった面積なので今後アパート規模の建築も予想され、将来的な採光は期待できない。このような背景から「丘陵地かつ低層高密度な住宅地での建ちかた」「隣家との高低差を鑑みた低コストな造成」について考えた。

隣家のブロック塀の土圧、道路との擦付け、前面道路が狭いことによる最低限の土の搬出、擁壁範囲の削減を考慮し造成を整理する過程で、１本の対角線が生まれた。先行して行われた造成の最中、敷地へ訪れると隣家の影は南側を埋め尽くし、その差もあってだろうか、北側はいつもより明るく輝いていた。

そこで、その対角線を活かし、「影を羽織るように家と庭を対角に等分して配置する」ことを考えた。家は隣家の影を羽織りながら光を北側へと導く三角錐状をベースとし、庭は導かれた光を浴びて、１日を通して明るい状態とした。インテリアは庭に落ちてバウンドする北側光と、屋根に割いたスリットから落ちる日脚の南光を拡散させる素材で調律する。天井は庭の光を室内の奥深くまで届けるようにデッキプレートを貼り、夜間は様々な間接光が室内を彩るとともに、一条の光の筋を住宅街に零す。対角線にセットバックされた建ちかたのおかげで前面道路も明るく開放的となった。丘陵地でこのような建ちかたが群をなせば、高密度な住環境であっても明るい周辺環境が計画されうるだろう。「造成と影」という土地の文脈から生まれた対角線と光は家と庭の建ちかたに還元され、周辺環境を明るくするとともに昼夜を通して光と戯れるような住環境をつくることを目指したが、引き渡して数日後に訪れた生活の風景はこんな論理を笑い飛ばすかのように鮮やかに住みこなされていた。この住宅は「論理」と「寛容」で成り立っている。

※第36回美しいまちづくり建築賞/奨励賞

Earthwork and Shadows, Diagonals and Light, House and Garden

This is a house designed for a family of four, located in a residential area on hilly terrain. The plot is elevated about 2 meters above the road and only has access on the north side. The neighboring houses on the south and east sides are close to the property boundary, and although the west side is currently vacant land, its sizable area suggests that apartment-scale construction may arise there in the future, making it unlikely to ensure sunlight in the long term. Given this context, we considered two main challenges: how to build on hilly terrain in a low-rise, high-density residential area and how to achieve cost-effective earthwork while accounting for the height differences with neighboring properties.

In the process of organizing the earthwork, we addressed issues such as the earth pressure against the block wall of the neighboring property, minimizing soil removal due to the narrow front road, and reducing the area of retaining walls. From this process, a single diagonal line emerged. During the early stages of earthwork, a visit to the site revealed that shadows from the neighboring houses enveloped the south side entirely. Perhaps as a result, the north side appeared unusually bright.

Thus, we decided to utilize this diagonal line, envisioning a design where the house and garden are diagonally divided, “draped in shadow.” The house adopts a triangular pyramid shape, embracing the shadow cast by the neighboring house while channeling light toward the north. Meanwhile, the garden bathes in the guided light, remaining bright throughout the day. The interior design incorporates materials that diffuse the northern light reflected from the garden and the southern light streaming through slits in the roof. A deck plate ceiling was installed to deliver the garden’s light deep into the interior. At night, various indirect lights color the interior, while a beam of light escapes into the residential neighborhood. Thanks to the diagonal setback of the building, the front road also feels brighter and more open.

If such a design approach were to proliferate in hilly areas, it might create brighter surroundings even in high-density residential environments. The diagonal line and light, born from the site’s context of “earthwork and shadow,” were translated into the placement of the house and garden, aiming not only to brighten the surroundings but also to create a living environment that plays with light day and night. However, when I visited the house a few days after it was handed over, the vibrant living scene seemed to laugh off such theoretical musings. This house is a product of “logic” and “tolerance.”