What factors are considered when grading softwood

Question

If I just want some cheap material for a project, I often consider using softwood (meant for framing and construction uses) dimensional lumber. In case I pass by a Home Depot store and I have to pick up some scraps by the side of the road, what grade are those scraps? What kind of grades of lumber do contractors usually throw away?

Do they generally stock No. 2 or No. 3 grade lumber? Do they even carry No. 1? Is a stud always a No. 2?

Without relying on the lumber to be graded and labeled correctly, what factors can I look for to estimate the grade myself? Is it absence of knots, or just general appearance?

Answer 1

In general, lumber grade refers to how free the wood is from knots and similar defects. Exact definitions vary depending on the kind of wood.

The exact details for hardwood grades are a complicated mix of how many and how large "clear" (knot-free) or solid (no loose knots, no cracks) pieces one can get out of the board, and whether you want that clear grain on both sides or are willing to settle for just one being pretty. The grading is generally done by eye.

For softwood the system is based on structural strength rather than appearance, and the grading is supposed to be more rigorous since, literally, more rests on the accuracy of the tests.

To get uncommon grades -- weaker softwood or knottier/"rustic" hardwood -- you may need to hit real lumberyards or sawmills rather than hitting a big-box store. Whether the price difference justifies the effort will depend on your needs and local availability.

Note that the traditional solution for ugly wood was to paint it

Answer 2

Your local home store should define the grade of lumber that's on the shelf. If not, I'd ask an associate.

From my experience, the Home Depot around me usually has No. 1 through Construction Grade on stock for most sizes and it's always labeled.

Answer 3

Here is a document on grading hardwood lumber.

The important parts

Selects This grade is virtually the same as F1F except for the minimum board size required. Selects allow boards 4" and wider and 6' and longer in length. The Selects grade is generally associated with the northern regions of the USA and is also shipped in combination with the FAS grade. Often export shipments of upper grades are simply referred to as FAS. The conventional business practice for American hardwoods is to ship these upper grades in some combination. Working closely with the supplier will enable the buyer to be sure that the expected quality will be received. Whether FAS is combined with F1F (Face And Better) or Selects (Sel And Better) every board in the shipment must have a minimum of one FAS face.

The Number 1 Common grade is often referred to as the Cabinet grade in the USA because of its adaptability to the standard sizes of kitchen cabinet doors used throughout the United States. Number 1 Common is widely used in the manufacture of furniture parts as well for this same reason. The Number 1 Common grades includes boards that are a minimum of 3" wide and 4' long and will yield clear face cuttings from 662 ⁄3% (8 ⁄12ths) up to, but not including, the minimum requirement for FAS (831 ⁄3%). The smallest clear cuttings allowed are 3" by 3' and 4" by 2'. The number of these clear cuttings is determined by the size of the board. Both faces of the board must meet the minimum requirement for Number 1 Common.

Number 2A Common (No. 2AC) The Number 2A Common grade is often referred to as the Economy grade because of its price and suitability for a wide range of furniture parts. It is also the grade of choice for the US hardwood flooring industry. The Number 2A Common grade includes boards that are a minimum of 3" wide and 4' long that yield from 50% (6 ⁄12ths) up to, but not including, the minimum requirement for Number 1 Common (662 ⁄3%). The smallest clear cutting allowed is 3" by 2' and the number of these cuttings depends on the size of the board. If the poorest face meets the minimum requirements for Number 2A Common, it does not matter what the grade of the better face is.

And here is the softwood grading doc. It appears to be much more technical because softwoods tend to be used for different purposes than hardwoods. Most especially, hardwoods are used primarily for their 'look', furniture etc.

Select is actually better than #1 which of course is better than #2. (This is all US standards).