Complete Guide to Buying Lumber

Wood is the number one building material in many parts of the world and it can be used for constructing a variety of things. However, wood is easily damaged due to weather conditions or insects that may infest it. To ensure you get high quality lumber without any issues, check out this guide on how to buy your next piece from a hardware store.

The “where to buy wood for furniture making” is a guide that includes information on where to find the best deals and how to buy lumber.

Vintage lumberyard men posing painting.

While I’m not the most handy or crafty man, I do try to improve my DIY abilities whenever I can, as I’ve indicated in prior postings. Purchasing timber anytime I undertake a job that necessitates it is something that often leaves me perplexed.

You’d think purchasing timber would be straightforward; after all, it’s just a piece of wood, right? However, it’s a shocking amount of work. There are so many options that I frequently find myself roaming the lumber area of the home improvement shop for 20 minutes trying to figure out which pieces of wood I should purchase, even with a supply list in hand. Is there a common board? Structural? What is the difference between C and D quality plywood? Have you have your pressure treated?

When I’ve done lumber research, I’ve found that I can discover part of the information I need in one source and some in another. But I could never discover a single comprehensive reference that had all of the details in one place. So, in order to compile everything for myself and our readers, I decided to create this post. I understand that most of you will not be reading this for pleasure; instead, I hope that you will be able to file it away and return to it anytime you have a lumber-related query of any type.

Put your tool belt on and let’s get started.

Lumber comes in two varieties: softwood and hardwood.

Softwoods and hardwoods are the two forms of lumber. Conifer trees such as pine, fir, spruce, and cedar provide softwood timber. These woods are classified as such because they may readily be damaged with your fingernail. Softwood timber also absorbs and loses moisture more easily than hardwoods, necessitating additional care to ensure the wood’s long-term stability. When softwood is exposed to the weather, one approach to keep it sound is to pressure treat it. I’ll get to it later.

Large pile of lumber in home store.

Lumber made of softwood

Because conifer trees grow quicker than hardwoods, softwood timber is less expensive. As a result, softwood timber is largely utilized in construction, such as in the frame of a home or the construction of a deck. If you’re doing a DIY project at home, you’ll most likely utilize softwood timber. It’s easy to come by at your neighborhood big box home improvement shop.

Collection of softwood lumber.

Lumber made of hardwood

Hardwood timber is made from deciduous trees with wide leaves that fall off in the winter. Oak, maple, walnut, hickory, and mahogany are the most common trees from which hardwood timber is made. Most hardwoods (with the exception of balsa wood) are tougher than softwoods and are less readily dented, as the name suggests.

Because hardwood trees take significantly longer to reach maturity, the timber they produce is far more costly than softwood ones. As a result, fine woodworking, furniture manufacturing, cabinets, and flooring are all common uses for hardwood timber. You’ll mostly be dealing with hardwoods if you want to go into woodworking. However, big box hardware shops seldom carry it, so you’ll have to go to a specialist woodworking store or a lumberyard to get it.


Let’s dive into the nitty gritty of each kind now that we’ve established the fundamental differentiation between softwood and hardwood lumber.

Lumber made of softwood

Classifications and Grades of Softwood Lumber

Because each tree is unique, individual pieces of timber will have a broad range of strength quality. The American Softwood Timber Standard was created by the US Department of Commerce to guarantee that the proper sort of lumber is used for the right application.

Softwood lumber is divided into three categories: yard, structural, and shop and factory. Let’s take a closer look at each of them.

Lumber for the Yard

Lumber that is meant for general construction and building. Yard timber is normally assessed visually, which means that an inspector assesses the appearance of the lumber before assigning a grade. Yard timber is further divided into two types: common and choice.

Lumber from the Backyard. Common timber is rated using a number classification and is acceptable for building and utility purposes:

  • Common No. 1 The highest grade of common wood. There will be a few tiny, tight knots in No. 1 common timber.
  • 2nd most common. Knots are bigger than in No. 1 Common. No. 2 is a popular choice for paneling and shelves, as well as basic woodworking jobs.
  • Common No. 3 Has a larger number of knots than No. 2. The wood is usually blemished and damaged. Fences, boxes, and crates are all good candidates.

Choose Yard Lumber. Because it has no or few knots, select yard timber looks significantly finer than ordinary lumber. Select yard timber is suitable for natural and painted finishes because to its beautiful look.

A letter classification is used to classify select yard lumber:

  • Choose C. It is commonly utilized in interior trims and cabinets because it is almost defect-free.
  • Select D. It has a nice look, although there are a few little knots.

Collection of lumber wood quality.

A visual representation of the different grades. Take note of how they continue to become worse and uglier. No. 3 is still a nice piece of wood, but it isn’t as attractive as No. 1.

Structural Lumber is a kind of wood that is used to build structures.

Lumber wood with background.

You’ve purchased structural timber if you’ve ever bought a 24 or a 44. The thickness and breadth of structural timber are all the same. The most typical structural timber sizes in America are the “two-bys” (2x4s, 2x6s, 2x8s, 2x10s) and the 44 (though we’ll see in a minute that a 24 isn’t truly 2 inches thick and 4 inches broad). The length is not standard, but the thickness and breadth are. A twenty-four might be six, eight, or even 10 feet long. It’s still a 24 percent. Carpenters and house framers may acquire timber without having to trim it when they receive it to the job site because of the conventional pre-cut sizes.

Because structural timber is often used in construction, it is frequently machine stress graded so that builders can determine the board’s bending stress. It may also be rated visually.

There are seven different types of structural lumber:

1. Use a light frame. Lumber with a thickness of 2 to 4 inches and a width of 4 inches. Construction, Standard, or Utility are the three grades. Here’s what the letters stand for:


  • Construction. Small, tight knots and knotholes are allowed if the following rules are followed:
Width Nominal On Wide Face, somewhere Knots and Holes that are unsound or loose
2″ 3/4” 5/8”
3″ 1-1/4” 3/4”
4″ 1-1/2” 1”
  • Standard. Splits at the board’s end are allowed as long as they aren’t longer than the board’s width. Tight knots and knotholes are allowed if the following rules are followed:
Width Nominal On Wide Face, somewhere Knots and Holes that are unsound or loose
2” 1” 3/4”
3” 1-1/2” 1”
4” 2” 1-1/4”
  • Utility. Splits up to 1/6 the width of the item are permitted. Knots are allowed in the following sizes and have no quality restrictions:
Width Nominal On Wide Face, somewhere Knots and Holes that are unsound or loose
2” 1-1/4” 1”
3” 2” 1-1/4”
4” 2-1/2” 1-1/2”

2. Light Framing in Structure. 2 to 4 inch thick and 2 to 4 inch broad lumber. Select Structural, 1, 2, or 3 are the grades. Here’s what the letters stand for:

  • Choose Structural. There aren’t many knots. There are a few knots here and there, but they’re little and tight. The most advanced of the four grades.
  • No. 1: Tight knots up to 1-1/2″ are permitted. Loose knots are only allowed to be 1″ broad and arise once every 3 feet.
  • No. 2: Well-spaced knots up to 2″ broad of any quality. Every 2 feet, knotholes up to 1-1/4″ diameter are possible.
  • Knots of any grade may measure up to 2-1/2″ in width. Every 1-3/4″ foot, knotholes are permitted.

3. The studs 2 to 4 inch thick and 2 to 4 inch broad lumber. Stud is the highest grade.

4. Joists and Planks for Structural Support Lumber with a thickness of 2 to 4 inches and a width of 6 inches or more. Select Structural, 1, 2, or 3 are the grades.

5. Stringers and Beams Lumber that is at least 5 inches thick and has a breadth that is at least 2 inches bigger than the thickness. Select Structural is the strongest, while Select Structural is the weakest.

6. Timbers and posts 5 x 5 x 5 x 5 x 5 x 5 x 5 x 5 x 5 x 5 Select Structural, 1, or 2 are the grades.

Appearance Framing is number seven. Structural timber that is at least 1 inch thick and 2 inches broad falls into this category. The grading of appearance framing is governed by aesthetics. Any knots or imperfections are absent or almost absent in the highest grades. Paneling and siding are made from appearance frame lumber. Finish and Select are the two main types of appearance framing. The Finish grade is superior than the Select grade in terms of quality.

Finish grading is only available in Douglass and Hem-Fir timber. Supreme, Choice, and Quality are the three classifications.

All Western softwood species get select grading. A, B, C, and D are the letter grades:

  • A good choice. There are no apparent knots, cracks, or other flaws. Fine furniture, exposed cabinets, trim, and flooring are all examples.
  • Choose B. There are a few minor flaws, but it’s almost flawless. Cabinets, trim, and flooring with exposed cabinetry, trim, and flooring.
  • Choose C. Knots that are close together. It’s suitable for shelves, as well as some trim and flooring.
  • Numerous “pin” knots and other minor imperfections on D Select.

Lumber from the shop and the factory

This is timber that has been chosen for “remanufacturing purposes” and is not designed for structural use. Shop and industrial timber is often used to make doors, ladders, pencils, molding, and boxes. The grade will be different based on how it will be utilized. As a result, shop timber used to construct doors will be graded differently from shop lumber used to create pencils. While each usage has its own grading system, the grade is usually determined by how much high-quality wood can be extracted from a given piece of timber for the intended purpose.


Moisture Content at the Time of Production

Lumber grading groups indicate the moisture content of the wood at the time it was made into lumber (“surfaced”) in addition to the quality of the lumber. This is crucial to know since softwood timber shrinks as it cures. This might affect how it’s utilized on the work site.

  • S-GRN. The surface is in good shape.
  • S-Dry. The surface was completely dry. After manufacturing, the moisture content was less than 19 percent.
  • MC15/KD15. At the time of production, the moisture content was 15% or below.
  • Kiln-dried and heat-treated (KDHT). must be dried

The Lumber Stamp Brings It All Together

Look for a stamp on the timber that looks like this the next time you’re in the hardware store picking up some wood for your project:


STAND & BTR indicates that the light framing has been evaluated as “Standard and Better.” So this piece of timber is standard at the very least, but it may well be Construction grade.

S-DRY indicates that the timber has been surface dried.

The D-FIR in the triangle indicates that this piece of timber comes from a Douglas fir.

All of the information we just discussed is included in one little stamp. So you can tell the sort of tree the timber originated from, its classification, grade, and moisture content simply by looking at it. Isn’t it amazing?

Working with Softwood Lumber That Has Been Pressure Treated

Three softwood lumber with white background.

Softwood timber that will be exposed to the weather is often pressure treated with a chemical that prevents the wood from decomposing due to water and fungus. Pressure-treated timber is often used to construct decks, light posts, swing sets, mailbox posts, picnic tables, and other structures.

The procedure of pressure treatment is rather straightforward. The to-be-treated wood is packed inside a sealed tank. The air is pulled out, forcing the pores in the wood to open up. A preservation chemical is injected into a tank and pushed deep into the wood’s cells by applying pressure. The wood is then removed and allowed to dry after the treatment. The green tint and mild moisture of pressure-treated timber may be identified at the hardware shop.

The Environmental Protection Agency classifies several of the chemicals used in pressure treating timber as pesticides, so caution should be used while handling it. Never use pressure-treated wood for mulch or compost, and never use it in your fireplace or campfire. Also, after touching it, you should wash your hands to remove any testosterone-sapping xenoestrogens that may have remained on your skin.

Lumber made of hard wood

Hardwood Dimensions

Hardwood lumber does not have conventional widths like structural softwood lumber, but it does have standard thicknesses. Hardwood is divided into quarter-inch pieces. The following is a chart of hardwood timber thicknesses:


Size Estimates Size/Name Nominal Dimensions in Actual (in)
(Inches) (quarter) (Fraction In) (Fraction Out) (Fraction Out) (Fraction S1S1) S2S2)
1/2″   3/8″ 5/16″
5/8″   1/2″ 7/16
3/4″   5/8″ 9/16″
1″ 4/4 7/8″ 13/16″
1 1/4″ 5/4 1 1/8″ 1 1/16″
1 1/2″ 6/4 1 3/8″ 1 5/16″
2″ 8/4 1 13/16″ 1 3/4″
3″ 12/4 2 13/16″ 2 3/4″
4″ 16/4 3 13/16″ 3 3/4″

Classification and Grading of Hardwood Lumber

The categorization and grading of hardwood lumber is substantially easier than that of softwood timber. The look of hardwoods is the most important aspect in grading. In the United States, the National Hardwood Lumber Association oversees the standard grading system for hardwoods.

There are four types of hardwood lumber. The quantity of clear surface area on a certain board’s worst-looking side determines its grade (with hardwoods one side will look better than the other). A higher-grade board is long and broad, with a considerable proportion of defect-free surface area. With a few major cuts, the transparent timber may be removed from the board.

Lumber wood measurements illustration.

A piece of FAS hardwood timber in action.

  • FAS stands for Familial Affection Syndrome (First and Second). This is the greatest level of excellence. An FAS board must be at least 6 inches broad, 8 to 16 feet long, and 83.3 percent clear on the side with the worst appearance.
  • Choose a board that is at least 3 inches broad, 4 feet long, and 66.6 percent free of defects (No. 1 Common).
  • Choose — No. 2 Common. A board that is at least 3 inches broad, 4 feet long, and 50% free of defects is required.
  • Choose — No. 3 Common. A board with a minimum width of 3 inches, a length of 4 feet, and a blemish-free percentage of 33.3 percent.

When providing the aforementioned ratings, you check for distinct criteria for different hardwoods. For further information, go visit the National Hardwood Association’s website.

Common Defects in Lumber

Because of the way the tree developed or how it was machined during the milling process, both softwood and hardwood timber will contain flaws. While faults in fine woodworking products may be dealt with and integrated, imperfections in structural timber should be kept to a minimum. Keep your eyes peeled for the following typical flaws:

Lumberwood bow illustration.

A bow is a warp that runs from end to end over the face of a board.

Wood cup illustration.

Cup. The board has a hollow across its face.

Wood wrap crook illustration.

Crook. A crown is a warp that runs along the edge line. This is particularly typical in timber harvested from the tree’s heart.

Lumber wood split illustration.

Split. A crack that runs the length of the piece of wood, usually at the ends.

Wood twist illustration.

Twist. When the ends of a piece of timber twist in opposing directions, it is called warping.

Lmber wood check illustration.

Check. The crack runs along the yearly growth rings of the wood, rather than across the full thickness of the wood.

Lumber wood shake illustration.

Shake. Grain separation between the growing rings, which may run the length of the board’s face and even below its surface.

Wood wane edge illustration.

Wane. Along the edge or corner of the item, there is missing wood or untrimmed bark.

Lumber wood tightknot illustration.

Knots and knotholes are two types of knots. Tight knots aren’t normally an issue. They’re going to remain. Knots that are loose may fall out, compromising the wood’s structure.

Understanding Lumber Sizing: A 24 Isn’t Really a 24

“Two-bys” and 4x4s are the most frequent kind of timber used for tasks around the home. Those figures, once again, pertain to the board’s thickness and breadth. A 24 refers to a piece of wood that is 2 inches thick and 4 inches broad.


Except that’s not the case.

The 24 (like with the other two-bys) employs a “nominal” measurement. Mills usually cut a tree into lumber soon after it has been felled, so the wood has a lot of moisture in it. When a piece of timber is cut into a 24 by the mill, it is really 2 inches thick by 4 inches broad. However, the timber shrinks as it dries on the way to the lumberyard. By the time you purchase that 24, it’s approximately 1-1/2″ x 3-1/2″ or so, give or take.

So keep that in mind the next time you’re working on a project and purchasing timber.

Paneling and Plywood

Lumber wood paneling illustration.

A discussion about timber would be incomplete without including plywood. Plywood is widely utilized in building projects such as flooring, roofing, and siding. You’ll utilize plywood if you ever decide to build your own plyometrics box for your garage gym (coming soon on AoM!).

The fact that plywood is robust, lightweight, and stiff makes it a popular choice. A single panel of plywood may cover enormous distances without bending due to its construction. Even if it does crack, it does not crack completely.

Plywood is created by stacking thin wood veneer pieces known as “plies.” Each layer is bonded together after being rotated 90 degrees from the one underneath it. Plywood’s strength comes from its layered composition.

Because just one side of the plywood is visible when it’s placed, only one side seems smooth and attractive. The “face” is the name given to this side. The rough side is referred to as “the rear.”

Softwood, hardwood, or a mix of the two may be used to make plywood. The majority of the plywood you purchase at the hardware store for home projects is made of softwood timber.

Grades of Plywood

There are a few different plywood grading systems, but the majority of them use an A-D system, with A being the best. Exterior, Exposure 1, Exposure 2, and Interior plywood are all types of plywood. The kind of plywood you pick will be determined by cost, the amount of exposure the wood will have to the weather, and whether or not appearance is important to you.

  • Exterior. Fully waterproof bond (glue) between the layers, suitable for applications that are exposed to weather and moisture on a regular basis.
  • Exposure 1: Fully waterproof bond, but not for long-term weather or moisture exposure.
  • Interior type with moderate bond, exposure 2. Intended for use in covered construction projects where a small amount of moisture is anticipated.
  • Only for use in the inside of a building.

If you’re short on cash and don’t mind if your plywood isn’t perfectly flat on the surface, opt for a lesser quality. It’s equally as powerful as the more attractive grades.

  • A. Paintable, smooth surface. Repairs to the veneer, such as removing knots with patches, are allowed, but only up to 18. Cabinets are an example of a project where this material is used.
  • Solid surface (B). Splitting is allowed to a certain extent.
  • C. Knots and knotholes must be tight. Surface discolouration and sanding faults are acceptable as long as they do not compromise strength.
  • D. Knots and knotholes of greater size are allowed.

Plywood with two grades, such as “A-C,” is common. This indicates that the front side is an A and the rear side is a C.


Plywood is classified as Sheathing, Stud I-Floor, and siding in addition to the aforementioned two classes. This simply defines the final usage for which a piece of plywood was created. Sheathing refers to the plywood you purchase at the hardware store for tasks around the home, such as building a workbench.

Plywood, like softwood timber, will have a stamp on the board with all of this information. It appears as follows:

Lumber wood rating chart.

So there you have it. Almost everything you’ll ever need to know about timber is here. Make a note of it and return to it the next time you need to purchase wood from a lumberyard. I hope you found this information helpful!

Good luck with your pounding!

Good luck with your pounding!


4th Edition Pocket Reference

The University of Missouri is located in Columbia, Missouri.

Western Wood Products Association is a non-profit organization that promotes the



The “lumber grades chart” is a guide to buying lumber. It includes the different types of lumber, the best place to buy it, and what to look for when purchasing lumber.

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