American walnut

American walnut is one of the most sought-after species in markets across the world and is unique to North America.

Latin Name

Juglans nigra

Other Common Names

black walnut

American_walnut_big
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American walnut trees grow very widely across the eastern USA in mixed hardwood forests and on farms, concentrated in central states but spread from Texas to the eastern seaboard. The trees are one of the few hardwood species planted as well as occurring and regenerated naturally. They grow relatively tall and straight with few lower branches.

FOREST GROWTH

FIA data shows U.S. walnut growing stock is 137.8 million m3, 0.9% of total U.S. hardwood growing stock. American walnut is growing 4.8 million m3 per year while the harvest is 1.9 million m3 per year. The net volume (after harvest) is increasing 2.9 million m3 each year. U.S. walnut growth exceeds harvest in all major supplying states except Michigan.

Alabama Arkansas Arizona California Colorado Connecticut District of Columbia Delaware Florida Georgia Iowa Idaho Illinois Indiana Kansas Kentucky Louisiana Massachusetts Maryland Maine Michigan Minnesota Missouri Mississippi Montana North Carolina North Dakota Nebraska New Hampshire New Jersey New Mexico Nevada New York Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Virginia Vermont Washington Wisconsin West Virginia Wyoming Volume of live trees on forest land, 1000 m³ 0 3.5K All data derives from The Forest Inventory and Analysis Database developed in 2001, a component of the U.S. Forest Service, Department of Agriculture.Data was compiled by AHEC in May 2020 using the most recent state inventory available (2018 for most states).“Forest volume” refers to “Net volume of live trees on forest land" as defined by FIA (see glossary). FIA forest volume data is available for 49 U.S. states (Hawaii and Washington D.C. are omitted) with total commercially significant hardwood forest volume of 14.6 billionWith the 2008 Farm Bill, every US State was tasked to prepare a Forest Action Plan by 2010, reviewed in 2015, to include comprehensiveassessment of forest condition and a strategy for sustainable forestry. Further details are available from theNational Association of State Foresters
Back to whole mainland U.S. 0-20K 20K-40K 40K-60K 60K-80K 80K-100K 100K-120K > 120K Volume of live trees on forest land, 1000 m³ 0 200K
-15K -10K -5K 0 5K 10K 15K 20K 25K GROWTH AND REMOVALS, 1000 m³ -10K -9K -8K -7K -6K -5K -4K -3K -2K -1K 0 1K 2K 3K 4K 5K 6K 7K 8K 9K 10K GROWTH AND REMOVALS, 1000 m³ -2000 -1750 -1500 -1250 -1000 -750 -500 -250 0 250 500 750 1000 1250 1500 1750 2000 GROWTH AND REMOVALS, 1000 m³ -300 -200 -100 0 100 200 300 400 500 GROWTH AND REMOVALS, 1000 m³ Removals 0 Growth 0 Net growth 0
0 200K 400K 600K 800K 1M 1.2M FOREST VOLUME, 1000 m³ 0 40K 80K 120K 160K 200K 240K 280K 320K 360K 400K 440K FOREST VOLUME, 1000 m³ 0 10K 20K 30K 40K 50K 60K 70K 80K 100K FOREST VOLUME, 1000 m³ 0 4K 8K 12K 16K 20K FOREST VOLUME, 1000 m³ Forest volume 0

LCA Tool

4.85
seconds
it takes 13.09 seconds to grow 1m³ of American walnut
The replacement rate is calculated from total U.S. annual increment of the specified hardwood species derived from the U.S. Forest Service Inventory and Analysis (FIA) program and assumes that 2 m³ of logs is harvested to produce 1 m³ of lumber (i.e. 50% conversion efficiency). The rapid rate of replacement is due to the very large volume of hardwood trees in U.S. forest.

Global Warming Potential (Kg CO2 -eq)

03000-30006000-6000

Primary Energy Demand from Resources (MJ)

04000-40008000-8000

Primary Energy Demand from Renewables (MJ)

020000-2000040000-40000

Acidification Potential (Moles of H+ eq.)

04-48-8

Freshwater Eutrophication Potential (Kg P -eq)

00.002-0.0020.004-0.004

Marine Eutrophication Potential (Kg N -eq)

00.07-0.070.14-0.14

Photochemical Ozone Creation Potential (Kg NMVOC)

04-48-8

Resource Depletion (Kg Sb -eq.)

00.0003-0.00030.0006-0.0006
Key
Forestry
Drying
Sawmill
Transport Forest-Kiln
Transport Kiln-Customer
Carbon uptake
Global Warming PotentialPrimary Energy Demand from ResourcesPrimary Energy Demand from RenewablesAcidification PotentialFreshwater Eutrophication PotentialMarine Eutrophication PotentialPhotochemical Ozone Creation PotentialResource Depletion
UnitKg CO2 -eqMJMJMoles of H+ eq.Kg P -eqKg N -eqKg NMVOCKg Sb -eq.
Forestry
/320115000.347/0.0004130.4360.0000025
Drying
58.789016700.4210.0009250.02851.530.0000439
Sawmill
-14683223100.2650.0001640.005390.1890.000226
Transport Forest-Kiln
55.476612.30.2550.000390.00650.320.0000335
Transport Kiln-Customer
214286043.33.160.001020.05912.460.00012
Carbon uptake
-2930///////
Total-27505670155004.440.00250.09994.940.000426
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Walnut from the USA is available as sawn lumber and as veneer. The lumber is generally sold un-steamed and unselected for colour. Specialist producers may offer steamed walnut intended to darken the sapwood and thus reduce the colour difference between heartwood and sapwood. Recent years have seen huge global demand for this species. NHLA Grading Rules are modified for walnut, allowing smaller specifications and smaller clear cuttings and sapwood is admitted without limit. Consultation with suppliers is recommended. 

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  • The sapwood of walnut is creamy white, whereas the heartwood is light brown to dark chocolate brown, making the difference in colour quite distinct. Occasionally the heartwood has dark, even purple, streaks. The wood of walnut is generally straight grained, although sometimes with wavy or curly grain that produces its characteristic and attractive figure, sought after by designers.
     
  • American walnut is quite different to European walnut, which tends to be lighter in colour. 

Mechanical Properties

Walnut is tough, hard and of medium density. It has moderate bending and crushing strengths and is low in stiffness. It has good steam bending classification.

  • 0.55

    Specific Gravity (12% M.C.)

    609 kg/m3

    Average Weight (12% M.C.)

    10.20%

    Average Volume Shrinkage (Green to 6% M.C.)

    100.677 MPa

    Modulus of Rupture

    11,584 MPa

    Modulus of Elasticity

    52.264 MPa

    Compressive strength (parallel to grain)

    4,492 N

    Hardness
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Oiled
American_walnut_oiled
Un-oiled
American_walnut_unoiled
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  • American walnut works easily with hand and machine tools. It has excellent planing, turning and moulding properties. It has good nailing and gluing properties and can be stained and polished to an excellent finish. The wood dries slowly and has good dimensional stability when dry.
     
  • The wood is rated as very resistant to heartwood decay and is one of the most durable (decay resistant) American hardwoods.
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Walnut is considered one of the supreme species for high end furniture, cabinets, doors and interior joinery. It is used for flooring and panelling and it is widely used to contrast with other hardwoods.

Flooring
Furniture
Doors
Panelling
Cabinets

Examples of Use

Boss table by RIVA 1920
Erasmus Medical Centre by Claus en Kaan Architecten
The Coach house by Isis Architecture
The Lantern by Fraher Architects
Zayed University Library by Hadi Teherani
Gaiola credenza by Tree Couture