The term “grade” refers to both the durability and the appearance of redwood lumber. Grades of redwood lumber are determined using criteria outlined by the Redwood Inspection Service (RIS). The grades help determine the best use for redwood based on its durability and appearance.
Understanding the durability of the wood is important because it helps determine the best use for the lumber (e.g. ground-contact vs. above-ground). Appearance is particularly important in the case of redwood because it has so many variations in color and the presence of knots.
Redwood is graded for durability and resistance against insects and decay – factors easily distinguished by redwood’s color. Reddish-brown heartwood from the inner portion of the tree contains extractives that render it resistant to insects and decay. As a general rule, all heartwood grades of redwood will have the word “Heart” in the grade name. For uses where the wood will be on or near soil, such as posts, bulkheads or patio grids, it’s essential to use one of the durable, heartwood grades – Heart Clear, Heart B, Deck Heart, Construction Heart or Merchantable Heart.
The cream-colored sapwood that develops in the outer growth layer of the tree does not possess the same resistance to decay and insects that redwood heartwood does. For construction above ground where there is little danger of damage from insects or decay, choose one of the sapwood grades – Clear, B Grade, Deck Common, Construction Common or Merchantable.
Excellence of appearance is a major factor in the grading of redwood. Freedom from knots, or clearness, is the determinant for the highest grades. Other grades are categorized by the number, size, and nature of knots as well as the presence of other characteristics such as stains or manufacturing defects that may occur.
Architectural grades of redwood include Heart Clear, Clear, Heart B and B Grade. Normally sold kiln dried (pre-shrunk and stress free), these grades are for the finest exterior and interior architectural uses. These finish grades are unrivaled in beauty and dimensional stability. They are the preferred grades for siding, paneling, trim and cabinetry where beauty and tight joinery are desired.
Garden grades of redwood include Deck Heart, Construction Heart, Deck Common, Construction Common, Merchantable Heart, and Merchantable. These grades may be offered seasoned or unseasoned. They are frequently specified for exterior and garden structures where knots or other characteristics have little or no effect.
Humboldt Redwood Heartwood - Architectural Grades
Redwood heartwood architectural grades are an excellent choice in applications where beauty, durability, and dimensional stability cannot be compromised. These grades should be used in applications where attractiveness and tight joinery are desired and may be used on or near the soil.
Finest architectural heartwood grade currently available, normally kiln dried (also available unseasoned), well manufactured, and free of defects on one face (reverse face may have slight imperfections). Available surfaced or saw-textured. Uses of Heart Clear redwood include siding, paneling, trim, cabinetry, molding, fascia, soffits, millwork. Also fine decks, hot tubs surrounds, furniture, garden structures, industrial storage and processing tanks.
Quality heartwood grade containing limited knots and other characteristics not permitted in Heart Clear. Available kiln dried or unseasoned. This grade can be surfaced or saw-textured. Uses of Heart B redwood include siding, paneling, trim, fascia, molding and other architectural uses. Quality decking, timbers, garden structures and other outdoor applications on or near the soil.
Humboldt Redwood Heartwood - Garden Grades
Redwood heartwood garden grades may be used on or near the soil in construction projects where knots or other characteristics are less important.
Deck Heart is an all heartwood grade containing knots of varying sizes and other slight imperfections; available seasoned or unseasoned. This highly useful grade is available surfaced or rough. Deck Heart has a similar appearance and uses as Construction Heart but is also graded for strength. Deck Heart is available in 2×4 and 2×6 only. Uses of Deck Heart include decks, fences, posts, retaining walls, garden structures, stairs or other outdoor applications on or near soil.
Construction Heart has a similar appearance and uses as Deck Heart, but is not graded for strength. It is an excellent heartwood grade recommended for many uses around the home, garden, and for general construction.
This economical heartwood grade allows for slightly larger knots than construction grades; holes limited to size of knots. Merchantable Heart allows checks, some splits and some manufacturing flaws; available unseasoned, surfaced or rough. Uses of Merchantable Heart include fences, retaining walls, and garden structures – especially on or near soil.
Humboldt Redwood Sapwood - Architectural Grades
Redwood sapwood architectural grades are unrivaled in beauty and dimensional stability. These grades should be used in applications where attractiveness and tight joinery are desired and where the building application is above-ground.
High-quality finish grade of the same general quality as Heart Clear. The principal difference between the two grades is that Clear contains sapwood. Typically available kiln dried (also available unseasoned). Available surfaced or saw-textured. Uses of Clear redwood include siding, paneling, trim, cabinetry, molding, fascia, soffits. Also quality decking, garden structures and other above-ground applications.
Quality grade containing sapwood, limited knots and other characteristics not permitted in Clear. Typically available kiln dried (also available unseasoned). Available surfaced or saw-textured. Uses of B Grade redwood include siding, paneling, trim, fascia, molding and other architectural uses; quality decking, garden structures and other above-ground applications.
Humboldt Redwood Sapwood - Garden Grades
Redwood sapwood garden grades should be used in above-ground construction projects where knots or other characteristics are less important.
Same general characteristics as Deck Heart, but contains a combination of heartwood and sapwood. Unseasoned or seasoned, may be surfaced or rough. Deck Common is also graded for strength and is available in 2×4 and 2×6 only. Uses include deck boards, rails, balusters, and other above-ground garden uses that do not require the insect and decay resistance of Deck Heart.
Same general characteristics as Construction Heart, but contains a combination of heartwood and sapwood.
Has the same characteristics as Merchantable Heart but contains sapwood in varying amounts. This economical grade is available unseasoned, may be surfaced or rough. Uses of Merchantable Redwood include fence boards, rails and other above-ground outdoor and garden uses; also subflooring and temporary construction.