Hardwood Lumber: Species, Grades, Thickness & Buying

Hardwood versus softwood

Hardwoods come from flowering trees; softwoods come from conifers. The terms do not rank every species by indentation resistance. Balsa is a hardwood despite being soft, while some softwoods can be harder than some hardwoods. For a project, compare the properties that affect its use rather than relying on the category name.

Domestic and imported species

Oak, maple, walnut, cherry and birch serve many interior furniture and millwork needs. Teak, Ipe and other imported woods have different identities, working properties and sourcing requirements. Domestic or exotic is not a quality grade. Confirm botanical identity, provenance and the characteristics of the supplied product.

Choose separately for appearance, machining, movement, intended exposure and connection design. The hardest wood is not always the easiest to machine or the most stable, and a species’ typical durability does not establish a guaranteed service life for an assembly.

Rough, S2S and S4S

Rough stock leaves machining work to the buyer. S2S generally means surfaced on two faces; S4S includes four surfaced sides. Ask what final dimensions are guaranteed and whether edges are straight and parallel. Quarter thicknesses such as 4/4, 5/4 and 8/4 describe nominal rough-stock conventions, not a guaranteed finished thickness.

A rough 4/4 board does not necessarily yield the finished thickness you need after flattening. Bow, cup, twist and defects consume material. Start with the final cut list and include enough allowance for the milling process.

Grade and usable yield

Hardwood appearance grades are based on specified rules and clear cuttings, not a guarantee of defect-free full boards. NHLA grading conventions and species exceptions require care. A lower grade may be economical for short parts, while long, wide clear components can need a different selection.

Compare the cost of producing the same finished parts. Do not count purchase waste and the same recovery loss twice. Include milling, offcuts, selection, freight and handling when comparing quotations.

Lumber, plywood and flooring are separate products

Solid lumber is sold for further manufacture and assembly. Plywood has a veneer/core construction with different movement and structural behavior. Finished flooring has a profile, construction, finish and installation system. Link the material choice to the appropriate buying guide rather than substituting one product simply because it is wood.

Specify the order

Provide species, grade definition, nominal and required finished dimensions, rough or surfaced condition, moisture target, length schedule, quantity and allowable substitutions. Ask for a quote date and the price unit—board foot, linear foot, piece or area.

Use the specification form below to carry these details into a sourcing request. A request starts a review; it does not certify availability or submit an order to a supplier.