Going into a lumber yard is a bit like walking in a maze. Every aisle seems to look the same. There are piles of wood stamped in ways that appear hard to understand. Most folks grab straightest board they can find and hope it works out. Often, it doesn’t. Knowing what wood grade are will help you make sure the right type of wood is matched to project so there are no worries about structural issues or warped shelf down the road.
There are three general categories in the grading system: 1) plywood panels; 2) hardwood for furniture and flooring; and 3) softwood structural lumber. The lingo is different within each category. For example, a FAS hardwood board is not the same than a Grade A plywood face. And because they’re separate organizations, each grading body set the rules for quality on its own. This infographic explain it all.
How to Choose the Right Wood Grade
One thing you want to be sure of when buying softwood framing lumber is its grade (for strength). The Western Wood Products Association do that. For any piece that bears a load, such as a header or beam, select No.1 or Select Structural. Knots are weak spots in tension, so they limits the number of knots allowed in these higher grades. For regular stud walls, use No. 2. It has fewer restrictions on wane and knots; it’s strong but less expensive. For temporary forms, go to No. Use No. 3 or Utility. A cheap grade for a beam with a load is not a good idea. Strength rating is your friend, it’s safe.
Grading: When it comes to hardwoods, appearance drive the price. Instead, wood graders at the National Hardwood Lumber Association grade on clear cut yield. The highest grade (FAS) demands the greatest amount of clear surface area; buy this if you’re looking for fine furniture or visible cabinetry. For trim and flooring, you might get away with using Selects or No.1 Common, which give you more flexibility in terms of board size and character. Use these grades for pieces that’ll be stained or otherwise hidden from view. It’s easy to waste money chasing FAS for tiny shelf brackets. Remember: You’re paying for clear space that you’ll end up throwing away.
This is about plywood grading. There are also some plywood grading codes that makes people scratch their heads. For example, the APA has two-letter codes (AC, BC, etc.). The first is the face grade, the second the back. An “A” is smooth-sanded and is suitable for veneer or paint. A “D” is rough with knots; this is for hidden layers only. Therefore, don’t purchase a CDX sheet of wood for a project where the plywood are going to show. The X does NOT mean good looking; rather, it’s for how well it last when exposed. Always verify both letters when purchasing if there is potential for the back side to be exposed.
When buying lumber, inspect what you buy. Always look at the grade stamp on the end of the board. If it has one. It will tell you who milled it, the species and the moisture content. Then look down the length of the board and make sure it isn’t twisted or bowed. Nothing that is crooked can be graded out.
Hardwood should be stored flat and allowed to acclimate to the humidity in your shop before cutting. Wood move! Don’t think it doesn’t, and you’ll have gaps. Match the grade to the use not your ego. You don’t need an FAS for a rustic-looking barn door, but you would of needed one for a kitchen cabinet. Get the right wood for the right job. Save yourself money and time. The stamp is accurate, but it might not meet your expectations.
