Recent Rationalization of Fire Safety and Structural Building Standards for Wooden Buildings - Difference between fire-resistant and Quasi-fire-resistant construction

Sep 15, 2026

Uploaded by Noah

The document explains the recent rationalization of fire safety and structural building standards for wooden buildings, focusing on how fire-resistant and quasi-fire-resistant construction are defined in terms of damage during fire exposure and after the exposure ends. It traces the evolution of timber-related regulations in Japan’s Building Standards Regulation across enforcement milestones, highlighting key developments in CLT (cross-laminated timber) design, testing, and verification methods. It also presents an example of a long-duration quasi-fire-resistant mid-rise project and summarizes related fireproof performance standards rationalized by building stories.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages13

Reading Time33 min

AccessFree to download

Difference between fire-resistant and Quasi-fire-resistant construction

Definitions and performance during/after fire exposure

Evolution of Timber-related Regulations in the Building Standards Regulation

Timeline: 1987, 1993, 2000, 2015-2020, 2024

Example of Long-Duration Quasi-Fire-Resistant Structure

Mid-Rise Building Project Using Long-Duration Quasi-Fire-Resistant Design

Rationalization of Building Standards for Promotion of Wood Use, etc.

Shift to overall wood / partial wood / lower-part wood construction

[Miscellaneous] Story-based fireproof performance standards rationalization

Recent Rationalization of Fire Safety and Structural Building Standards for Wooden Buildings Hiroaki Nishimura Senior Deputy Director Counsellor’s office for Building Regulations, Housing Bureau Ministry of Land, Infrastructure, Transport and Tourism Government of Japan 29 May 2025 Ministry of Land, Infrastructure, Transport and Tourism Difference between fire-resistant and Quasi-fire-resistant construction |
Fire-resistant construction is a structure that does not suffer damage or similar deterioration even when exposed to fire heat for a specified period of time. Quasi-fire-resistant construction is a structure that does not suffer damage or similar deterioration while being exposed to fire heat for a specified period, but allows for such damage to occur after the exposure ends. | | | | | --- | --- | --- | --- | | | While being heated | After heated | | | Fire-resistant construction | Resistance to damage, heat insulation, and prevention of flame penetration are ensured. | Resistance to damage, heat insulation, and prevention of flame penetration are ensured. | | | Quasi-fire-resistant construction | Resistance to damage, heat insulation, and prevention of flame penetration are ensured. | ― | | Concept Evolution of Timber-related Regulations in the Building Standards Regulation | Year of
enforcement | Structural provisions | Fire safety provisions | | --- | --- | --- | | 1987 | | Enabled large-section timber structures using calculation of residual cross-section based on charring | | 1993 |
5 × 5

| Permitted timber construction of three-story apartment buildings outside fire protection and quasi-fire protection zones.(Note: Since 2000, also permitted in quasi-fire protection zones)） | | 2000 | | Enabled fire-resistant construction using timber. | | 2015 | Full-scale Seismic Testing of Buildings Using CLT (Cross-Laminated Timber) | Enabled construction of three-story timber school buildings and similar structures. | | 2016 | -Developed general design methods for buildings using CLT (e.g., 5-layer, 5-ply configurations) .
-Added new connection methods joining columns to foundations and sill plates using dowels and tenons. (2016,2017) | | | 2018 | Added specified strength for thinner CLT panels such as 3-layer, 3-ply configurations. | Full-scale fire test of a three-story wooden school building | | 2019 | Added higher specified strength for CLT based on JAS-specified species groups and grading classifications.
(Announced on December 12, 2018; enforced on March 12, 2019) | Enabled calculation of residual cross-section based on charring for mid-rise wooden buildings(Exposed timber design)
(Announced June 27, 2018; enforced June 25, 2019) | | 2020~ | In collaboration with the Forestry Agency, the addition of specified strength for a wider range of layer configurations is under consideration. | Introduced a verification method allowing exposed timber design without requiring ministerial certification.
(Announced and enforced February 26, 2020) | | 2024 | Established of a specification-based design method (scheduled for FY2024). | Allowed partial timber construction or timber construction of lower floors in large-scale buildings.
(Announced June 17, 2022; enforced April 1, 2024) 6 | | Based on scientific findings obtained through full-scale fire tests and full-scale shaking table tests of building materials and components, technical confirmation of evacuation safety, structural safety, and other factors has been made, and rationalization is being implemented accordingly in a phased manner. | | | --- | --- | Example of Long-Duration Quasi-Fire-Resistant Structure Mid-Rise Building Project Utilizing Long-Duration Quasi-Fire-Resistant Design | Awa Mokuyon Project | | | | | | --- | --- | --- | --- | --- | | -Organizer: Tokushima Prefecture
-Selected Proposal by: Uchino Architects / Omishi Shimazu Architectural Design Office / Kawaguchi Tei Architectural Plann

FAQs

How do fire-resistant and quasi-fire-resistant constructions differ in fire exposure outcomes?

Fire-resistant construction does not suffer damage or similar deterioration even when exposed to fire heat for a specified period. Quasi-fire-resistant construction does not suffer damage or similar deterioration during exposure, but allows such damage to occur after the exposure ends.

Which major milestones advanced timber-related fire safety and structural regulations?

The document highlights key enforcement steps such as enabling large-section timber structures based on charring (1987), allowing three-story timber apartments outside certain zones (1993) and permitting fire-resistant timber construction (2000), followed by CLT-focused testing and strength/connection method updates through 2015-2024.

What is the purpose of rationalization in building standards for wood use?

Rationalization is implemented in phases based on scientific findings from full-scale fire tests and shaking table tests, supporting evacuation safety, structural safety, and broader adoption of wood construction methods.

Sep 15, 2026

Uploaded by Noah