Publication of Seismic Simulation Results Corresponding to the 2025 Building Standards Act Revision
The 100% Earthquake-Resistant Housing Executive Committee published a seismic simulation report corresponding to the April 2025 law revision. It proved that required wall quantities increase by 1.41x, but Seismic Grade 3 homes will not collapse.
📋 Article Processing Timeline
- 📰 Published: April 2, 2026 at 22:00
- 🔍 Collected: April 2, 2026 at 13:34
- 🤖 AI Analyzed: April 21, 2026 at 06:36 (449h 1m after Collected)
The 100% Earthquake-Resistant Housing Executive Committee (Location: Chiyoda-ku, Tokyo) has published a report summarizing the results of a seismic simulation using the wooden house collapse analysis software "wallstat", in conjunction with the revision of the Building Standards Act (review of wall quantity standards, etc.) enacted in April 2025.
In this verification, using an actual property damaged in the Kumamoto earthquake (Residence Y) as a model, an analysis was conducted to compare the revised new standards (2025 standards) with the old standards (2000 standards) and to identify the differences in safety based on calculation methods.
* The wall multiplier for the load-bearing walls used in this verification is uniformly set to 2.5 times.
■ Background: Heavier Buildings Due to Energy Efficiency and Legal Revision
In the April 2025 legal revision, against the backdrop of buildings becoming heavier due to energy-saving measures, the standards were revised to calculate the required wall quantity according to actual conditions. In response to this, the committee conducted a detailed simulation to visualize the impact the new standards will have on actual seismic resistance.
Conclusion: It was confirmed that Seismic Grade 3 does not collapse even under wall quantity calculations.
■ Main Verification Results
1. Increase in Required Wall Quantity Due to Legal Revision
Comparison of Required Wall Ratios under the Building Standards Act
When calculating the wall quantity coefficient using the "New Wall Quantity Table Calculation Tool (Multifunctional Version)", comparing the old standards (2000 standards) for "light roofs" and the current standards (2025 standards), the current standards showed an average increase of 1.41 times compared to the old standards.
Comparison of Required Wall Ratios under the Housing Quality Assurance Act
Comparing the old standards (2000 standards) and the current standards (2025 standards) under the Housing Quality Assurance Act specification provisions: for Seismic Grade 1, it was 30.5 ÷ 27.2 = 1.12 times; for Seismic Grade 2, 38.5 ÷ 34 = 1.13 times; and for Seismic Grade 3, 46 ÷ 41.1 = 1.12 times, resulting in an average of 1.12 times.
2. Safety of "Seismic Grade 3"
As a result of conducting a simulation using the seismic waves from the Kumamoto earthquake on a model house designed based on the new standards, it was demonstrated that buildings with "Seismic Grade 3" do not reach the point of collapse or major damage.
In this verification, using an actual property damaged in the Kumamoto earthquake (Residence Y) as a model, an analysis was conducted to compare the revised new standards (2025 standards) with the old standards (2000 standards) and to identify the differences in safety based on calculation methods.
* The wall multiplier for the load-bearing walls used in this verification is uniformly set to 2.5 times.
■ Background: Heavier Buildings Due to Energy Efficiency and Legal Revision
In the April 2025 legal revision, against the backdrop of buildings becoming heavier due to energy-saving measures, the standards were revised to calculate the required wall quantity according to actual conditions. In response to this, the committee conducted a detailed simulation to visualize the impact the new standards will have on actual seismic resistance.
Conclusion: It was confirmed that Seismic Grade 3 does not collapse even under wall quantity calculations.
■ Main Verification Results
1. Increase in Required Wall Quantity Due to Legal Revision
Comparison of Required Wall Ratios under the Building Standards Act
When calculating the wall quantity coefficient using the "New Wall Quantity Table Calculation Tool (Multifunctional Version)", comparing the old standards (2000 standards) for "light roofs" and the current standards (2025 standards), the current standards showed an average increase of 1.41 times compared to the old standards.
Comparison of Required Wall Ratios under the Housing Quality Assurance Act
Comparing the old standards (2000 standards) and the current standards (2025 standards) under the Housing Quality Assurance Act specification provisions: for Seismic Grade 1, it was 30.5 ÷ 27.2 = 1.12 times; for Seismic Grade 2, 38.5 ÷ 34 = 1.13 times; and for Seismic Grade 3, 46 ÷ 41.1 = 1.12 times, resulting in an average of 1.12 times.
2. Safety of "Seismic Grade 3"
As a result of conducting a simulation using the seismic waves from the Kumamoto earthquake on a model house designed based on the new standards, it was demonstrated that buildings with "Seismic Grade 3" do not reach the point of collapse or major damage.