Impact of Japanese Building Code Revisions

Since Japan's fiscal year begins in April, revisions to laws often take effect at that time. The upcoming revision to the Building Standard Law, set to take effect in April 2025, is expected to significantly impact renovations. As a result, many homeowners in Japan are rushing to complete their renovations before the new law is enforced.

What Changes Are Coming in the 2025 Building Standard Law Revision?

In Japan, building renovations generally require approval through a process known as building confirmation. This involves submitting an application to ensure the renovation complies with regulations and undergoing an inspection after completion to verify compliance.

Until now, wooden one-story and two-story homes with a total floor area of 200 square meters or less were exempt from these requirements, allowing many homeowners to renovate without filing for a building permit. However, starting in 2025, all two-story wooden buildings, regardless of their size, will require a building permit. This change will affect a significant number of private wooden homes across Japan.

The need for a building permit will increase renovation costs due to the application and inspection fees, as well as the time-consuming approval process. Additionally, the revised law not only expands the scope of required applications but also increases the number of documents needed. Homeowners will have to submit detailed structural and energy efficiency reports, making the renovation process even more complex and costly.

Impact on Older Buildings

Japan’s frequent building code revisions mean that many older buildings do not comply with current regulations. These structures are generally exempt under a grandfather clause unless major renovations are undertaken. However, bringing an older building up to modern code―especially one built before 1981―can be extremely costly. In many cases, it may be cheaper to rebuild rather than renovate.

Previously, homeowners could renovate older two-story wooden houses (under 200 square meters) within their budget without applying for a permit. However, after the revision, large-scale renovations will need to meet modern seismic and energy efficiency standards, significantly raising costs.

Rising inflation, increasing material and energy costs due to the weak yen, and labor shortages have already driven up construction expenses. Some builders believe that with the new legal requirements, renovating an old building could become even more expensive than constructing a new one.

As a result, more old buildings may be demolished instead of renovated, leading to the loss of historic townscapes and culturally significant structures. This is particularly concerning in areas with narrow streets where emergency vehicles cannot enter, making these buildings "non-reconstructable properties." Since new buildings cannot be constructed on such sites under current laws, large-scale renovations requiring a permit will also be prohibited. Unless local governments introduce special measures to preserve historic areas, many cultural landmarks may disappear.

While high-rise apartments are common in Japanese cities, two-story wooden homes remain prevalent in suburban and rural areas. Especially, many traditional streets and buildings, like those shown in the photo, do not comply with current building codes and could be at risk due to the upcoming law changes.

Can Homeowners Apply for a Building Permit Themselves?

Legally, homeowners can apply for a building permit without being licensed architects or professionals. However, the application process requires specialized architectural knowledge and advanced Japanese language skills. As a result, most homeowners hire Japanese design firms or architects to handle the paperwork.

Even if a homeowner manages to complete the application independently, they must still pay inspection fees, as the local government or a private inspection agency will review and verify compliance after completion.

Do Small-Scale Renovations Require a Permit?

A building permit is required for major renovations, defined as modifications affecting more than 50% of the primary structural components (such as walls, columns, floors, beams, roofs, or stairs). However, for one-story wooden buildings under 200 square meters, permit exemptions will continue even after the law revision, allowing large-scale renovations without a formal application. (Even a wooden one-story building with a total floor area of 200 square meters or less may require a building permit if it is located in a densely populated urban planning area.)

For larger buildings, some homeowners might try to avoid the permit process by breaking renovations into smaller stages. However, if construction phases are too close together, authorities may consider them part of a continuous renovation, requiring a permit.

Regardless of whether a permit is needed, all renovations must comply with the Building Standard Law. Any violations or unsafe modifications could result in government-issued correction orders or penalties.

Major renovations, such as tearing down walls and floors or altering floor plans, will likely require a building permit under the revised law.

What Happens if You Renovate Without a Permit?

Renovating without a required building permit is a legal violation. If discovered, local authorities will issue a correction order. If homeowners comply, there are usually no major consequences. However, failing to correct the violation could result in penalties, including up to one year of imprisonment or a fine of up to one million yen.

Other Important Considerations for Building Permits

Once a building permit is approved, all renovations must follow the submitted plans. Minor modifications, such as repositioning fixtures, can be reported later under a "minor change" procedure. However, major changes, like altering the floor plan, require a formal "plan modification application" before making adjustments.