When a storm blows through the wind loads on your fence can be incredibly high and all of that load is transferred onto the post. Nails, screws and other fasteners used with pressure treated wood should be double hot dipped galvanized or stainless steel ASTM A 153 Class D.2×4 rails in 8-foot lengths are commonly used. Pressure treated fence rails should be AWPA grade UC3B if left unpainted, grade UC3A if painted or finished with an opaque stain.Avoid peeler cores when selecting 4” x 4” x 8’ fence posts. Pressure treated posts should be rated for ground contact – AWPA grade UC4A for general purpose or UC4B for heavy duty.You might also be interested in learning about the actual thickness of a sheet of plywood.There are many different types of wood lumber and grades available at your local home improvement store so it is important to know the important items when purchasing the materials for your repair. Table showing the nominal and actual thicknesses of hardwood lumber Nominal Size Refer to the table below to see the thicknesses of hardwood lumber that is rough or surfaced. For example, a 4/4 board is 1” thick when it’s purchased rough, but is 7/8” thick after surfacing one side and is 13/16” thick after surfacing two sides. These designations are important since they impact the actual thickness of a board. Boards that have been surfaced are referred to using the designations S1S, S2S, S3S, or S4S, depending on how many surfaces have been planed. To make things more confusing, hardwood lumber is also sold either rough sawn or surfaced on one, two, three, or all four sides. For example, a 1” thick board is referred to as 4/4. Quarters refer to the number of quarters of an inch of board thickness. Hardwood lumber is often sized by the thickness of the board, which is measured in quarters rather than inches. Calculating board feet can be a little tricky, but it’s essentially just a measurement of the volume of the board. Hardwood lumber is sold very differently from dimensional lumber and is usually measured by the board foot. Modern sawmills typically account for this, however, and dimensional lumber is generally pretty consistent.īonus: Hardwood Lumber Sizes & Dimensions Today, boards are intentionally cut large to allow for shrinkage during kiln drying and the milling process.īecause the amount a board shrinks can vary by wood species, moisture content, and even the individual tree, the final size may vary slightly. Historically, softwood logs were cut green into 2×4 but would naturally shrink as the boards dried out, and after planing and milling, they ended up around 1.5×3.5. Why is dimensional lumber smaller than the nominal dimensions? If the nominal size is 8” or larger, then the actual size of the board will be 3/4” smaller.If the nominal size is larger than 2” and smaller than 8” then the actual size is 1/2” smaller than the nominal size.If the nominal size is smaller than 1” then the actual size is 1/4” smaller than the nominal size.If you’re stuck without a tape measure or reference table you can also use a simple rule of thumb to determine the actual size of dimensional lumber. Table showing the nominal size and actual size of dimensional lumber in inches and millimeters Nominal Size Refer to the table below to see the actual size of lumber. The board is advertised and sold using the nominal dimensions, which are a bit larger than the actual size. The actual sizes of a board are smaller than that.įor example, a 2 x 4 board is actually 1 1/2″ x 3 1/2″. These are the dimensions of the board before it’s been dried and milled. Dimensional lumber is lumber that has been dried and milled to standard dimensions and is most commonly used for framing and construction.ĭimensional lumber is sold using what is referred to as the nominal dimensions of a board. Most softwood lumber sold at the lumber yard is dimensional lumber. You might be wondering “what’s the deal?” Why is lumber advertised using dimensions that are inaccurate?īelieve it or not, this is not an error at the factory or a big corporation trying to take advantage of you, and there is actually a reason for this. Hopefully you haven’t been burned by assuming that a 2 x 4 is actually 2 inches by 4 inches but if you have, know that you’re not alone. You may have seen framing lumber and softwood boards sold at your local lumber yard or hardware store advertised using dimensions that don’t match the actual size of the board. Save on Pinterest Save Share on Facebook Share Share on Twitter Tweet
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