How Lumber is Graded & What it Means for Your Fence
All lumber- wood that’s been manufactured into boards and planks for construction- is graded on a scale of Clear (0) to 3. The lumber manufacturing process first became standardized in 1924 with the publication of the American Lumber Standard. This standard is now called the American Softwood Lumber Standard- because it pertains solely to softwood used for the majority of commercial construction- and it establishes lumber sizes, methodology for assigning design values, nomenclature, inspection and re-inspection procedures, an accreditation program, and, finally- a National Grading Rule.
The purpose for grading lumber is two-fold: to determine the structural integrity and create a standard to rate the aesthetic quality of a piece of lumber. When a tree is cut into boards, each board comes from a different section of the tree. Boards that come from the center of the tree- what’s referred to as heartwood- often have no knots or blemishes. Boards that come from the outer edge of a tree will typically have more knots and blemishes.
Why? Because of a tree’s branches.
All knots, essentially, are cross-cuts of tree branches. And because tree branches penetrate the outer edges of a tree more so than they do the center, boards that come from the outer edge of a tree have more knots.
Grade is determined by the type and position of knots and how they affect the structural integrity and appearance of a board.
A clear grade board has virtually no knots; the only knots permitted on a clear board are pin knots- knots smaller than ¼ inch in diameter- that only appear on one side of the board. Clear graded boards are the most expensive because they come from the center of mature trees. Although clear graded boards are blemish free, they have the same structural integrity of boards with a #1-2 grade; the main difference a 1 or 2 grade and clear graded boards- and fences- have a uniform appearance with no blemishes.
A #1-2 grade board is the highest quality board with knots. The type of knots on a #1-2 grade are tight and sound: pin knots, heart knots, and spike knots are typically the only knots you will find on a #1-2 grade board. These knots are secured in place because the branch they come from was still alive and growing when the tree was cut. You may notice that knots on a #1-2 grade fence are surrounded by bands of new growth, which a lot of fence owners find attractive.
A #2 grade board is still structurally sound but it will be knotty in appearance and include little to moderate defects. The knots on a #2 grade board are still secure, but you may notice that they are more frequent and some may be darker in color. #2 grade boards are the most economically priced pieces of lumber on the market; they have excellent structural integrity, but aren’t as uniform in color and appearance.
When you get to #3 grade board, the structural integrity of the lumber starts to be compromised. #3 grade boards will have moderate defects; it’s free of holes at the time of manufacture, but some of the knots allowed on #3 boards- like encased knots- may fall out as the board dries leaving you with holes in your fence.
The ideal fence is made from a variety of #1-2 or #2 boards; these fences won’t cost you nearly as much as an all clear fence, they will last for a long time if properly maintained, and- because the knots are secure and evenly distributed among the surface of the entire fence- they look wonderful.
Now that you know about fence grades, contact Texas Fence and let’s talk about the fence grade you want for your home or business.