Apitong wood movement calculator

Dipterocarpus spp. · imported

Handbook listing: Apitong

Janka
Density
T/R ratio
2.1
Spec. gravity

Apitong (Dipterocarpus spp.) is an imported species. The Wood Handbook strength tables list no matched specific gravity or hardness for it, so those fields are shown as “—”. It shrinks 10.9% tangentially and 5.2% radially from green to oven-dry (T/R ratio 2.1), so a 12-inch flatsawn board moves about 0.26 in (≈ 1/4 in) across a 6-point moisture swing (about 6%→12% MC).

Compute Apitong: movement, weight & board footage

Every number below is worked from Apitong's own shrinkage and density figures, not looked up from a table — change the width, moisture swing, or board size in the calculators linked alongside.

Cross-grain movement by board width

Cross-grain change for a 6-point moisture swing (≈ 6%→12% MC), using ΔD = D × (S ÷ 30 ÷ 100) × ΔMC.
Board width Flatsawn (tangential) Quartersawn (radial)
2″ 0.044″ (≈ 1/32 in) 0.021″ (≈ 1/32 in)
3″ 0.065″ (≈ 1/16 in) 0.031″ (≈ 1/32 in)
4″ 0.087″ (≈ 3/32 in) 0.042″ (≈ 1/32 in)
6″ 0.131″ (≈ 1/8 in) 0.062″ (≈ 1/16 in)
8″ 0.174″ (≈ 3/16 in) 0.083″ (≈ 3/32 in)
10″ 0.218″ (≈ 7/32 in) 0.104″ (≈ 3/32 in)
12″ 0.262″ (≈ 1/4 in) 0.125″ (≈ 1/8 in)
16″ 0.349″ (≈ 11/32 in) 0.166″ (≈ 5/32 in)

Need a different width or moisture swing? Run the movement calculator preloaded with Apitong. At a T/R ratio of 2.1, Apitong is moderately unstable — it moves substantially more tangentially than radially, so flatsawn stock is noticeably cup-prone and quartersawn stock is worth the extra cost in wide panels.

Board footage and weight aren't shown for Apitong — the Wood Handbook strength tables carry no matched density for it, so a weight figure here would be invented rather than computed. The board foot calculator still works without a species; board feet don't depend on density.

Seasonal movement by city

Width change of a 12″ flatsawn board between each city's driest and most-humid month, from USDA equilibrium-moisture-content data.
City Driest month (EMC) Most-humid month (EMC) EMC swing 12″ board movement
Phoenix, AZ Jun · 4.4% Dec · 9% 4.6 pts 0.201″ (≈ 3/16 in)
Chicago, IL May · 12.3% Dec · 15.1% 2.8 pts 0.122″ (≈ 1/8 in)
Miami, FL Apr · 12.2% Sep · 14.4% 2.2 pts 0.096″ (≈ 3/32 in)
Boston, MA Apr · 11.5% Sep · 12.8% 1.3 pts 0.057″ (≈ 1/16 in)
Denver, CO Jul · 8% Dec · 10.5% 2.5 pts 0.109″ (≈ 3/32 in)
Seattle, WA Jul · 12% Dec · 16.9% 4.9 pts 0.214″ (≈ 7/32 in)

Driven by Apitong's tangential shrinkage of 10.9%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.

How Apitong compares

Ranked against the 196 species in the Wood Handbook tables this site carries.

About Apitong

Keruing or apitong (Dipterocarpus) is widely scattered throughout the Indo-Malaysian region. Most of the more than 70 species in this genus are marketed under the name keruing. Other important species are marketed as apitong in the Philippine Islands and yang in Thailand. Over-exploitation and habitat loss have resulted in most species receiving an IUCN rating of endangered or critically endangered. The heartwood varies from light to dark red–brown or brown to dark brown, sometimes with a purple tint; the heartwood is usually well defined from the gray or buff- colored sapwood. Similar to kapur (Dryobalanops), the texture of keruing is moderately coarse and the grain is straight or shallowly interlocked. The wood is strong, hard, and heavy (density of air-dried wood is 720 to 800 kg m–3 (45 to 50 lb ft–3)). This wood is characterized by the presence of resin ducts, which occur singly or in short arcs as seen on end-grain surfaces. This resinous condition and the presence of silica can present troublesome problems. Sapwood and heartwood are moderately resistant to preservative treatments. However, the wood should be treated with preservatives when it is used in contact with the ground. Durability varies with species, but the wood is generally classified as moderately durable. Keruing is easy to saw and machine, particularly when green, but saws and cutters dull easily as a result of high silica content in the wood. Resin adheres to machinery and tools and may be troublesome. Also, resin may cause gluing and finishing difficulties. Keruing is used for general construction work, framework for boats, flooring, pallets, chemical processing equipment, veneer and plywood, railroad crossties (if treated), truck floors, and boardwalks.

Wood Handbook, Chapter 2: Characteristics and Availability of Commercially Important Woods (M.C. Wiemann), USDA Forest Products Laboratory, FPL-GTR-282 (2021), p. 27. Public domain.

Properties

At 12% moisture content unless noted.
Specific gravity
Janka hardness (side)
Density (air-dry, 12% MC)
Weight per board foot (air-dry)
Radial shrinkage (green→oven-dry) 5.2%
Tangential shrinkage (green→oven-dry) 10.9%
Volumetric shrinkage (green→oven-dry) 16.1%
T/R ratio (stability indicator) 2.1

Shrinkage is total green-to-oven-dry (Table 4-4); strength values are at 12% MC. Full bases and the derivation formulas are on the methodology page. Values shown as “—” have no matched entry in the Wood Handbook strength tables (5-3b/5-5b).

Data: USDA Forest Products Laboratory, Wood Handbook FPL-GTR-282 (2021), public domain.