The Japanese “Zairai” timber construction method is a traditional post-and-beam system that uses vertical posts, horizontal beams, and diagonal braces.
It has been used for centuries and is still one of the most common wooden construction methods in Japan today.
■ Feature 1: High flexibility in room layout
Because the structure relies on posts and beams, interior walls can be added or removed more freely compared to panel-based systems.
This makes renovations and layout changes easier.
■ Feature 2: Excellent adaptability for renovation
As long as the main structure remains intact, interior modifications, equipment updates, and layout changes can be handled flexibly.
This matches Japan’s strong renovation culture.
■ Feature 3: Earthquake-resistant design
Diagonal braces and structural walls are placed strategically to resist lateral forces during earthquakes.
Modern metal connectors and structural calculations allow Zairai houses to achieve high seismic performance.
■ Comparison with 2×4 Construction
| Item | Zairai (Timber Frame) | 2×4 (Platform Frame) |
|---|---|---|
| Structural method | Posts & beams | Wall panels |
| Layout flexibility | ◎ High | △ More limited |
| Renovation suitability | ◎ Easy to modify | △ Restrictions due to wall structure |
| Construction speed | △ Slower | ◎ Faster |
| Seismic performance | ◎ Adjustable by design | ◎ Standardized |
■ Why Zairai is widely used in Japan
- Suitable for earthquake-prone regions
- Strong traditional carpentry culture
- Popular renovation market
- Flexible layout modifications
■ Required Disclaimer
※This article explains Japanese building practices and regulations.
※Regulations vary by country. Please check your local codes.
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