Regulatory Update for the Japanese Market: New JAS Species Groups “JS A” and “JS T”

On March 3, 2026, the Japanese government promulgated a revised official notification (formerly Ministry of Construction Notification No. 1452) concerning the reference strengths of structural lumber for platform frame construction. These new building code regulations will be officially enforced starting May 29, 2026.

For Canadian lumber exporters, this revision introduces an important shift in how competing domestic Japanese timber is categorized and evaluated by structural designers.

1. Establishment of Independent Domestic Categories

The core of this revision is the creation of dedicated, independent species groups for domestic Japanese timber within the Japanese Agricultural Standard (JAS).

• “JS A” (Akamatsu / Japanese Red Pine): Previously, Akamatsu was often evaluated against or categorized alongside the broader “D Fir-L” (Douglas Fir-Larch) group.
• “JS T” (Todomatsu / Todo Fir): Previously, Todomatsu was evaluated against or categorized alongside the “S-P-F” (Spruce-Pine-Fir) group.

By establishing these new groups, the Japanese regulatory bodies are separating domestic materials from imported categories to apply structural values that reflect actual domestic timber testing.

2. Comparative Strength Advantage for Canadian Lumber

Following testing by the Materials and Durability Working Group on March 6, 2026 , the newly revised reference strengths (Fc, Ft, Fb) and the published Modulus of Elasticity (MOE) for “JS A” and “JS T” have been set significantly lower than their Canadian counterparts.

This downward adjustment for domestic species highlights the continued superior structural performance and reliability of Canadian D Fir-L and S-P-F. A comparison of the primary structural grades (Class Kou: Special Grade and Grade 2) illustrates this advantage:

D Fir-L vs. JS A (Akamatsu) Reference Values

Units: Reference Strength (N/mm2), Reference Modulus of Elasticity (kN/mm2)

Grade	Species Group	Compression (Fc)	Tension (Ft)	Bending (Fb)	Modulus of Elasticity
Class Kou, Special	Canadian D Fir-L	25.8	24.0	36.0	12.6
	Domestic JS A	23.8	11.6	22.2	9.8
Class Kou, Grade 2	Canadian D Fir-L	19.2	15.0	21.6	10.7
	Domestic JS A	19.2	6.2	15.4	7.8

S-P-F vs. JS T (Todomatsu) Reference Values

Units: Reference Strength (N/mm2), Reference Modulus of Elasticity (kN/mm2)

Grade	Species Group	Compression (Fc)	Tension (Ft)	Bending (Fb)	Modulus of Elasticity
Class Kou, Special	Canadian S-P-F	20.4	16.8	30.0	10.5
	Domestic JS T	18.2	18.0	24.0	9.5
Class Kou, Grade 2	Canadian S-P-F	17.4	11.4	21.6	9.6
	Domestic JS T	16.6	12.9	17.3	8.9

3. Unchanged Specifications

It should be noted that the bearing reference strengths (compressive strength perpendicular to grain) remain unchanged from the previous regulations.

4. Market Implications and Opportunities

Starting May 29, 2026, Japanese builders and structural designers will be required to apply these lower design values when utilizing domestic “JS A” and “JS T” lumber. Because substituting Canadian lumber with domestic alternatives will now mathematically result in reduced structural capacities and higher deflection rates, this regulatory update provides an excellent opportunity for Canadian suppliers to reaffirm the superior strength-to-weight ratio and cost-efficiency of Canadian S-P-F and D Fir-L in the Japanese 2×4 housing market.