Sal
Shorea robusta
Also known as sakhua, sarai · Botanical Shorea robusta
Revision history
- — Data re-verified in site-wide audit (formulas, sources, durability classes)
- — Working properties and comparable-species data cross-checked against listed sources
About Sal
Sal (Shorea robusta) is a mid-range timber, hard enough for everyday wear and still easy to work, with a Janka hardness of 1,340 lbf (5,960 N) and a density of about 0.74 g/cm³. It grows in India and South Asia.
At 4.0% radial and 7.5% tangential the T/R ratio is 1.88 — typical, and manageable in exterior joinery and cladding provided the gaps are designed rather than assumed. Its fibre saturation point is near 27%. Below it, movement is the governing constraint on this species: 7.5% tangential against 4.0% radial, a T/R ratio of 1.88. Flatsawn boards will cup; quartersawn stock is worth the premium here. — wide boards need real expansion room, not a token gap.
At 740 kg/m³ a cubic metre of Sal weighs about 740 kg air-dry — that figure, the 7.5% tangential and 4.0% radial movement and the 1,340 lbf hardness are the three inputs the calculators below actually consume. Select Sal in any of them to get species-specific results for weight, moisture, shrinkage and hardness.
Working properties
How Sal behaves at the bench and on the machine, drawn from the World Agroforestry Centre (ICRAF), the ITTO tropical-timber service and Indian forestry references.
Durability & use classification
Sal heartwood is durable (EN 350 Class 2), highly resistant to termites and decay, and it is noted in Indian forestry sources for its resistance to fire. This is the timber India has trusted for railway sleepers and structural work for well over a century. One honest note carried by ITTO: sal's quality and anatomical structure vary considerably from place to place.
Typical applications & suitability
Indoor Outdoor — A heavy structural timber first and foremost — specified where members carry serious stress — and durable enough for exposed and ground-contact work. Sacred to Hindus and Buddhists, it is among the most culturally significant trees of the subcontinent.
Documented end-uses: beams, pillars, posts and heavy house construction, railway sleepers and railway carriages, bridges and hydraulic engineering, ships and boats, telephone and electrical poles, window frames, flooring, furniture and heavy-duty packaging. The tree also yields sal dammar resin (used in varnishes and traditional medicine) and sal-seed oil.
Comparable species
Species closest to Sal by density, hardness, stiffness and bending strength, computed directly from the Vriksai species dataset rather than hand-picked.
Trade alternatives. Sal is a Shorea like Balau, and ITTO groups them together in trade. Within India, Teak is the more durable and workable premium alternative, while Keruing covers similar structural ground from South-East Asia.
Alternatives to Sal
Sal measures 1,340 lbf Janka at 0.74 g/cm³, EN 350 durability Class 2, movement rated Good. Because Sal is exterior-rated at Class 2, every candidate below is too. A substitute that quietly drops a durability class is the expensive kind of mistake. Read the numbers against the Janka scale and EN 350 durability classes.
For exterior joinery, cladding and garden work that also has to resist knocks. Harder means more dent resistance but heavier sections and more machining time.
Easier to work and lighter to fix, without dropping below the exterior durability you already have.
Cladding boards and exterior joinery live or die on movement. These give you less of it at equal or better durability. Size the gaps with the shrinkage predictor and EMC calculator.
If Sal is unavailable and the specification cannot change, these are the nearest substitutes across hardness, density, movement, stiffness, bending strength and durability class together — not on any single property. Lower distance means a closer match.
Computed from measured properties only — hardness, density, movement, stiffness, bending strength and EN 350 class. Price, availability and appearance are never inputs. Figures are representative values, not consignment absolutes: two species within a few percent are equivalent until verified on the material. Full method and the rules the engine cannot break.
Substituting outdoors is a match on durability class and movement first. Colour and grain can be matched later; a wrong durability class shows up as a callback in three monsoons. Where two candidates are close, compare them directly before specifying.
Compare Sal side by side
These are the head-to-heads that decide cladding, decking and exterior joinery specifications. Every pairing shows the measured figures side by side; full matrix in the comparison index.
Calculators relevant to Sal
Aimed at exterior detailing in Sal: coverage, gaps, coating and durability checks. Full set in the tool index.
Understand the figures
Thermal conductivity — k-value and insulation behaviour · ThermoWood species guide — Thermo-D/Thermo-S treatment classes · Janka hardness scale — how the lbf figure is measured · Wood density reference — oven-dry vs air-dry basis.
Further reading. Wood moisture content explained · How to calculate board feet.
Common questions about Sal
unverified no published source for this figure · calc derived from the figures above · — no published source found
A note on these figures. We have not been able to trace the numbers in the panel above to a named authority. The Wood Database has no Sal (Shorea robusta) entry and the USDA FPL Wood Handbook does not list it; ICRAF and ITTO, both cited below, cover its durability and machining but publish no mechanical table we could match. Where we have been able to check pages sourced this way, the figures have usually been wrong — so treat these as indicative rather than measured. The durability class, working properties and uses below are attributed to the bodies named in the sources list. If a number here matters to your work, verify it against a source you are willing to rely on, or test your own stock.