Is sugi good for outdoor use?

Yes — the heartwood is durable, with good natural decay and insect resistance, the basis for centuries of Japanese exterior architecture and for charred 'yakisugi' siding; the sapwood, however, is perishable. Reference figures are USDA Forest Products Laboratory values at 12% moisture content.

How hard is sugi and how does it work?

Sugi is soft and light, with a Janka hardness of 510 lbf. It cuts very cleanly under hand or power tools and planes glassy, but it dents easily and splits readily along the grain — the property behind traditional shake and shingle work.

What is sugi used for, and where does it come from?

It is used for temple and shrine architecture, interior paneling, sake barrels, joinery, shoji and tansu, and yakisugi siding. Sugi is native to Japan, where plantation stock is the standard commercial source. Raw Heartwood kiln-dries its lumber to 6-8% moisture content.

ExoticCryptomeria japonica

Sugi

Temple wood. Sake barrel wood. The wood of yakisugi siding.

Sugi (Cryptomeria japonica), or Japanese cedar, is an exotic softwood with a Janka hardness of 510 lbf. Its warm pinkish to reddish-brown heartwood — sometimes showing the prized black 'kuro' zones — is soft, light, aromatic, and naturally decay-resistant.

Category: Exotic
Janka: 510 lbf
Botanical: Cryptomeria japonica
Shipped at: 6–8% MC

Cryptomeria japonica Japanese Cedar · Japanese Cedar · Native to Japan

Native to Japan.

National tree of Japan. Heartwood warm pinkish-brown to reddish-brown, sometimes with darker streaks and the black "kuro" zones the Japanese trade prizes.

Detail of Sugi grain — figured wood texture, photographed at Raw Heartwood — A close read on the grain. Detail of this specimen

What you see.

Heartwood warm pinkish-brown to reddish-brown, sometimes with darker streaks and the black "kuro" zones the Japanese trade prizes. Pale cream sapwood, sharp line. Darkens to amber with age.

Heartwood color detail of Sugi (Cryptomeria japonica)

Heartwood, this specimen

How the grain runs.

Straight. Medium to coarse texture. Strong earlywood-to-latewood contrast — softwood ring figure shows clearly. Slight luster under finish.

Closer in

On the bench.

Heartwood durable. Good natural decay and insect resistance — the basis for centuries of Japanese exterior architecture. Sapwood is perishable. Very easy. Soft, light, clean-cutting under hand or power. Planes glassy. Splits readily along the grain — the property that runs traditional shake and shingle work. Takes hand-tool finishes beautifully. Glues and finishes well. Dents easily. Distinct spicy, slightly sweet aromatic at the cut. Hangs around in dry wood. Part of the cultural appeal. Sugi pollen drives one of the major hay-fever problems in Japan, but pollen is the tree, not the lumber. The wood dust can irritate lungs and sensitize some workers. Western redcedar is well documented for similar effects. Standard dust precautions.

The numbers, looked at directly.

Janka Hardness

0lbf

2,270 N. Side-hardness — force to embed a half-inch steel ball halfway into the wood.

Average Dried Weight

0lbs/ft³

420 kg/m³. At 12% MC.

Specific Gravity

0.34/ 0.42 at 12% MC

Basic over green volume; second number at 12% moisture content.

Hardness, in context

A side-hardness measurement. Higher number, harder wood.

Shrinkage — radial / tangential / volumetric

2.0%radial

4.0%tangential

6.5%volumetric

On sourcing

Where this wood comes from matters.

Not on CITES. IUCN Near Threatened in its limited natural range. Plantation sugi covers roughly 18% of Japan's forest area and is the standard commercial source. Supply is abundant.

What it's for.

Temple & shrine architecture
Interior paneling
Sake barrels
Boatbuilding
Joinery
Shoji & tansu
Yakisugi siding

Worth knowing.

National tree of Japan. Lines the approach to many shrines, including the Nikkō avenue. Yakushima's Jōmon Sugi and other ancient trees are protected national monuments. Yoshino, Akita, and Yakusugi are recognized as distinct quality grades. Old-growth Yakusugi is harvest-restricted now and prices reflect it. Yakisugi charred siding has driven recent international demand.

Sources & references.

Cryptomeria (Cryptomeria japonica) — Wikipedia contributors
Cryptomeria japonica — IUCN Red List — Katsuki, T.; Luscombe, D. (2013)
Sugi (Cryptomeria japonica) — The Wood Database
Forests and Forestry in Japan — Forestry Agency, Ministry of Agriculture, Forestry and Fisheries (MAFF)
Cryptomeria japonica — Gymnosperm Database — Earle, C.J.
Yakushima — UNESCO World Heritage Centre
Shrines and Temples of Nikko — UNESCO World Heritage Centre

Common questions.

Is sugi good for outdoor use?: Yes — the heartwood is durable, with good natural decay and insect resistance, the basis for centuries of Japanese exterior architecture and for charred 'yakisugi' siding; the sapwood, however, is perishable. Reference figures are USDA Forest Products Laboratory values at 12% moisture content.
How hard is sugi and how does it work?: Sugi is soft and light, with a Janka hardness of 510 lbf. It cuts very cleanly under hand or power tools and planes glassy, but it dents easily and splits readily along the grain — the property behind traditional shake and shingle work.
What is sugi used for, and where does it come from?: It is used for temple and shrine architecture, interior paneling, sake barrels, joinery, shoji and tansu, and yakisugi siding. Sugi is native to Japan, where plantation stock is the standard commercial source. Raw Heartwood kiln-dries its lumber to 6-8% moisture content.

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