Sweetgum (Liquidambar styraciflua) in numbers: hardness, weight, strength, shrinkage, movement and decay resistance, taken from the tables of the USDA Forest Products Laboratory’s Wood Handbook, followed by what the wood is like to work and what it is used for. The values are averages from small, clear, straight-grained test specimens; real boards with knots, sloping grain or a different moisture content will differ.
| Property | Sweetgum |
|---|---|
| Janka side hardness, 12% moisture | 850 lbf (3,781 N) |
| Janka side hardness, green | 600 lbf |
| Hardness rank | harder than 74 of the 168 woods with a 12% hardness value in our database |
| Density at 12% moisture | 36.4 lb/ft³ (582 kg/m³) |
| Weight per board foot (12%) | 3.03 lb |
| Specific gravity (ovendry weight, green volume) | 0.46 |
| Specific gravity at 12% moisture | 0.52 |
| Bending strength (modulus of rupture), 12% | 12,500 psi |
| Stiffness (modulus of elasticity), 12% | 1.64 million psi |
| Crushing strength (compression parallel to grain), 12% | 6,320 psi |
| Shrinkage green to ovendry: radial / tangential / volumetric | 5.3% / 10.2% / 15.8% |
| Tangential / radial shrinkage ratio | 1.92 |
| Dimensional change per 1% moisture (radial / tangential) | 0.00183 / 0.00365 |
| Impact bending (drop height to failure), 12% | 32 in. |
| Heartwood decay resistance | slightly or nonresistant |
What it is
Sweetgum (Liquidambar styraciflua) grows from southwestern Connecticut westward into Missouri and southward to the Gulf Coast. Almost all sweetgum lumber is produced in the Southern and South Atlantic States.
The lumber is usually sold in two kinds: sap gum, the light-colored sapwood, and redgum, the reddish-brown heartwood. Sweetgum often has a form of cross grain called interlocked grain. When quartersawn, the interlocked grain produces a ribbon-type stripe that is desirable for interior woodwork and furniture.
Working properties
The wood is moderately heavy and hard, moderately strong, moderately stiff and moderately high in shock resistance. Because of its interlocked grain it must be dried slowly. Its tangential shrinkage from green to ovendry is 10.2%, and in service a flatsawn board changes width by about 0.365% for each 1% change in moisture content, against about 0.183% for a quartersawn board.
Weight and density
At 12% moisture content sweetgum weighs about 36.4 lb per cubic foot, so one board foot (144 cubic inches) weighs about 3.03 lb. An 8 ft board of actual size 3/4 × 5-1/2 in. (a 1×6) holds 0.229 cubic feet and weighs about 8.3 lb; an 8 ft piece 1-1/2 × 3-1/2 in. (a 2×4 size) weighs about 10.6 lb. Green wood is much heavier because of the water it holds.
Density here is ovendry weight plus 12% water, divided by volume at 12% moisture content (Wood Handbook Eq. 4-12: density = specific gravity at 12% × 62.43 lb/ft³ × 1.12).
Wood movement
The Wood Handbook gives dimensional change coefficients for each species: the fraction of its width a board gains or loses for every 1% change in moisture content, between about 6% and 14%. For sweetgum they are 0.00365 across a flatsawn face (tangential) and 0.00183 across a quartersawn face (radial).
Worked example: a flatsawn board 7-1/4 in. wide (a nominal 1×8) that goes from 6% moisture content in a heated winter house to 12% in a humid summer changes width by 7.25 × 0.00365 × 6 = 0.159 in. (about 5/32 in.). The same board quartersawn moves 0.08 in. (about 3/32 in.). Allow for this in panels, tabletops and floors; the wood movement calculator works it out for any size and moisture range.
How it compares
| Species | Janka (lbf) | Density (lb/ft³) | Bending (psi) | Stiffness (Mpsi) | Tangential shrink (%) | Decay resistance |
|---|---|---|---|---|---|---|
| Sweetgum | 850 | 36.4 | 12,500 | 1.64 | 10.2 | slightly or nonresistant |
| Black tupelo | 810 | 35.0 | 9,600 | 1.2 | 8.7 | not rated |
| American sycamore | 770 | 34.3 | 10,000 | 1.42 | 8.4 | slightly or nonresistant |
| Yellow-poplar | 540 | 29.4 | 10,100 | 1.58 | 8.2 | slightly or nonresistant |
| Red maple | 950 | 37.8 | 13,400 | 1.64 | 8.2 | slightly or nonresistant |
| Black cherry | 950 | 35.0 | 12,300 | 1.49 | 7.1 | moderately resistant |
Uses
Lumber, veneer, plywood, slack cooperage, railroad crossties, fuel and pulpwood; boxes and crates, furniture, interior moulding and millwork.
Frequently asked questions
How hard is sweetgum?
Sweetgum averages 850 lbf (3,781 N) on the Janka test at 12% moisture content and 600 lbf green, a little softer than red maple (950 lbf) and black cherry (950 lbf).
What is the difference between redgum and sap gum?
They come from the same tree. Sap gum is lumber from the light-colored sapwood of sweetgum, and redgum is lumber from its reddish-brown heartwood.
Why must sweetgum be dried slowly?
It often has interlocked grain, a form of cross grain, and the Handbook says it must be dried slowly. Its tangential shrinkage from green to ovendry is 10.2%.
Can sweetgum be used outdoors?
Not untreated. Sweetgum heartwood is in the slightly or nonresistant decay class, so it needs preservative treatment or a protected location outdoors.
Sources
- USDA Forest Products Laboratory. Wood Handbook: Wood as an Engineering Material. General Technical Report FPL-GTR-190, 2010. Chapter 2 (species descriptions), Chapter 4 (Tables 4-3, 4-4 shrinkage; Eq. 4-7, 4-9, 4-12 density), Chapter 5 (Tables 5-3b, 5-5b strength and hardness), Chapter 13 (Table 13-5 dimensional change coefficients), Chapter 14 (Table 14-1 decay resistance)
- USDA Forest Products Laboratory. Wood Handbook, 2021 edition (FPL-GTR-282)
Last reviewed: 24 October 2026. Numbers are generated from our parsed copy of the Handbook tables, so every page uses the same data. Values marked * are estimates computed with the Handbook’s own equations. Spotted an error? Please let us know.