Garden structure (carport, bicycle shelter) rules in Tokyo

21 Jun 2025 | #housing | #japan

We are building a house in Tokyo. The house design is finalized, and the constructions is ongoing, so we are finalizing the garden design. One common thing to put into the garden is some sort of roof over either a car or bicycles, often referred to as カーポート(carport) and サイクルポート (cycleport). We just learned that there are rules about these.

After starting the house construction, we got a letter from the Building Supervision Department (建築指導課) of the city hall, reminding us that there are rules about building carports and cycleports, and asking us to confirm with them before we build anything. While these structures don’t require explicit building permits (unlikely houses), they still need to follow certain rules and the city hall staff can come and check it later, and could request to demolish a structure that doesn’t follow the rules.

We forwarded the mail from the city hall to our external construction company, and they received the following rules from the city hall.

Everything counts

Essentially by default all structures are considered like the house, so they have to be included in the building area (建築面積) calculations. E.g. our land has a limit of maximum 40% of the land can be covered with a building, and the overall floor space has to be less than 80% of the size of the land. Normally an outside structure (like a garage or shed) would be included in this calculation. Considering that most land are small in Tokyo, the houses are usually pushing very close to these limits (e.g. our house covers 39.3% of the land), which leaves no place for other structures.

The solution: Ministry of Construction Notification No. 1437

There are structures with high degree of openness (高い開放性を有すると認めて指定する構造) that don’t need to be included in the building area calculations, and Ministry of Construction Notification No. 1437 (建設省告示第1437号) defines the conditions for a structure to be classified as such.

The structure has to follow these:

1. The section without exterior walls must be continuously 4 meters or more in length. (外壁を有しない部分が連続して四メートル以上であること)
2. The spacing between columns must be 2 meters or more. (柱の間隔が二メートル以上であること)
3. The ceiling height must be 2.1 meters or more. (天井の高さが二・一メートル以上であること)
4. The number of floors, excluding basements, must be one. (地階を除く階数が一であること)

For cycleports, #1 and #4 are usually met, however we had to change our cycleport to a different model to meet #2 and #3: our original one was only 2m tall and the distance between the columns was less than 2 m as the colums weren’t at the corners, but at the .25 and .75 points of one long edge.

This led to a situation that due to checking these rules we ended up with a slightly larger cycleport than originally planned (about 10cm deeper and 50cm taller). This came as a surprise, as I thought the city hall will ask us to make it smaller not bigger. But the size is close-enough that the price doesn’t really change, and a taller structure will keep the space feel more open.

Mistakes in online sources

Many online sources (e.g. this) have #2 reversed, saying that the spacing between columns must be less than 2 meters (柱の間隔は２m以下であること). The official document that we got from our city hall (which is the same as the one from the ministry’s website) clearly says that it’s more than 2m (柱の間隔が二メートル以上であること), so I think the other online sources are likely wrong. But just in case, it is better to double check with your local city hall, since there could be different rules for different areas, and the city hall will know the rules that apply to your land.