Lumber: What to Know Before You Shop

A close-up of stacked lumber.

Lumber is an important material for many DIY projects, but selecting the right type of wood for the job is harder than it looks. From different lumber grades to exact board dimensions, here are a few things you should know before your next stop at the lumber yard.


You will typically find two types of wood in your local hardware store: hardwood and softwood. Softwoods are from coniferous trees, also known as evergreens. This type of lumber features small pores with straight grain, which makes them great for projects that require framing and construction. Softwood is more affordable than hardwood because of its fast growing nature. Examples of softwoods include fir, pine, spruce, and cedar.


Hardwoods come from deciduous trees, or ones that shed leaves annually. Denser than softwood, hardwoods feature prominent grain patterns that make them useful in a variety of woodworking projects. Hardwoods also contain larger pores than softwoods and are classified by the size of the pores. Common examples of hardwoods include oak, walnut, mahogany, maple, and hickory. Hardwoods are typically more expensive than softwoods because they do not grow as fast.

Pressure Treated Lumber

A fence made of pressure treated wood.

Softwoods may be great for construction projects, but they are also susceptible to fungus and rot. You avoid moisture problems by working with pressure treated lumber, which is ideal for outdoor projects like playgrounds, decking, mailboxes, and picnic tables. The treatment process leaves behind a green tint to the wood, making it easy to spot in the lumber yard. Some of the chemicals used to pressure treat lumber are considered pesticides so exercise caution when handling.

Reading Lumber

Lumber is usually stamped with a grade marker. The marker contains the mill number or name, a certification mark, the abbreviated grade, moisture content, and species. Not all stores use the same marks, so be sure to ask for clarification whenever in doubt.

Softwood Grades

Softwood grades are split into two divisions: appearance and dimensional lumber. Appearance boards have fewer defects and knots and are great for woodworking, while dimensional boards are used for strength. The highest grades are C and D Select, followed by 1, 2, and 3 Common.

Hardwood Grades

Hardwood grades come courtesy of the National Hardwood Lumber Association. The grading is based on how many defects are present in the board. The best hardwood grades are first and seconds, and select, followed by #1 and #2 Common. Although a board might be graded low, it still might work for your project, depending on the usage.


A stack of plywood against house framing.

Plywood is a go-to material in large constructions jobs like roofing and flooring because it's lightweight, rigid, and strong. Plywood is created by layering wood veneer into plies that are glued together. The face side of the plywood is smooth while the back is typically rough. The grade of plywood you should select depends on the project and whether or not you are concerned about looks.

Plywood Grades

Plywood grades are separated into two classifications. The first category is graded alphabetically from A to D, with A being the higher quality. It's then separated into exposure types, including Exterior, Exposure 1 and 2, and Interior. When examining a sheet of plywood, you will usually see two letters separated by a dash. The first letter corresponds to the face or smooth side of the plywood while the second letter refers to the rough side.


A damaged piece of weathered wood.

It doesn’t take much rummaging to discover defects in a lumber pile. Common defects include bowing between the ends, cracking along the surface, cupping across the face, dead knots, splits, and bends. You should always inspect a board entirely before making a purchase, as warped boards can create nightmares down the road.


Despite how lumber is advertised, the dimensions are almost never accurate. For example, a 2x4 is typically around 1-1/2” x 3-1/2”. The wood is off by half an inch because it loses moisture as it dries and shrinks. Keep this shrinkage in mind when planning your next DIY project.