Kento-kunThis memo provides a clear summary of the laws frequently used in the design of new wooden houses and small-scale buildings.
Kento-kunI’ve got to study hard again today!
Today, let’s learn when building confirmation is required for small wooden buildings, including so-called Category 3 buildings, even outside City Planning Areas.
Today’s basic design memo for wooden houses is about cases where an application for building confirmation is required even outside City Planning Areas and Quasi-City Planning Areas.
As a basic premise, Category 1 and Category 2 buildings under Japan’s Building Standard Act require building confirmation. Therefore, this memo focuses on buildings with two stories or less and a total floor area of 200 m² or less, excluding structures other than buildings.
| Area / designation | Legal basis | Overview |
|---|---|---|
| Quasi-Landscape District | Article 74, Paragraph 1 of the Landscape Act | A district designated outside City Planning Areas and Quasi-City Planning Areas. As of the end of March 2026, these districts had been designated in nine areas across seven municipalities, including Hiraizumi Town, Koya Town, Munakata City, and Satsumasendai City. |
| Areas designated by the prefectural governor | Article 6, Paragraph 1, Item 3 of the Building Standard Act | Areas designated outside City Planning Areas and Quasi-City Planning Areas. These tend to be designated mainly in existing settlements where a certain level of building density already exists. |
| Sediment Disaster Special Warning Area (Red Zone) | Article 25 of the Sediment Disaster Prevention Act | Buildings with habitable rooms located within a Sediment Disaster Special Warning Area are deemed to be located in an area designated by the prefectural governor. |
Kento-kunIt is also important to note that even when building confirmation is not required, a Construction Work Notification may still be required.A Construction Work Notification is submitted to the prefectural governor through the building official. However, if the total floor area of the building work is 10 m² or less, this notification is not required.
Kento-kunAnother important point is that the rule requiring building confirmation within Sediment Disaster Special Warning Areas is not directly stipulated in the Building Standard Act.
Kento-kunInstead, this requirement comes from the Sediment Disaster Prevention Act. Under this Act, a building with habitable rooms located within a so-called Red Zone, or Sediment Disaster Special Warning Area, is deemed to be located in an area designated by the prefectural governor.Therefore, it is important to understand that this rule is not set out directly in the Building Standard Act. Buildings without habitable rooms, such as warehouses or garages, are not subject to this rule.
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