The Trades

Research, insights and advice from craftsmen and industry experts

What Is Glue-Laminated Wood (Glulam)?

wood Nov 18, 2020

Short for “glue laminated timber,” glulam is a newly popular addition to the family of engineered wood products with an unusual name. Glulam beams offer a unique combination of beauty and strength. According to APA, the Engineered Wood Association, it’s stronger than steel.

“What’s great about glulam is that you can sand them and bring out all of the grains. You can use more exotic woods and get pretty beams that are actually structurally solid. You’ll see a lot more of this in the future.” -Professional builder Jordan Smith

While glulam has attracted the interest of builders and architects in recent years, it in fact has a long history. The original Swiss patent for this type of engineered wood dates back to 1901 and one of the earliest buildings in the United States using it was a USDA Forest Products Laboratory in Madison, Wisconsin that was completed in 1934—it is still in use today.

An old postcard showing the Forest Products...

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Types of Plywood, Grades, and Sizes

wood Oct 21, 2020

While it was invented in England, plywood was enthusiastically embraced in the United States beginning in the 19th century. To this day it remains a primary material in construction and home improvement projects—by one estimate, more than 680 million cubic feet of plywood are produced each year. 

With many houses, plywood forms the walls and floors. It is what keeps a house standing and the elements outside. After a frame is constructed, it’s necessary to fill in the spaces between those supports with weather resistant material.

“You also have to wrap this skeleton in a skin that keeps it from blowing down to take care of shear,” explains professional builder and craftsman Jordan Smith. “We could put braces up that keep that sideways force from toppling the building over, but we still have to worry about stuff like air and moisture infiltration. It doesn't do us any good to build a bunch of walls with a framed skeleton and not have any way of...

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Wood Foundations: PWF Pros, Cons, and Considerations

wood Oct 21, 2020

One of the five types of foundations common in the U.S., wood foundations have been built for hundreds of years. In the middle of the 20th century, however, a new type of wood foundation emerged—the permanent wood foundation, or PWF. It uses pressure treated wood to create foundations that are resistant to both rot and damage from insects. PWFs can, however, lead to surprisingly heated discussions among architects and builders who have strong opinions about when or even if wood foundations are a good choice. 

What Is a Permanent Wood Foundation?

Though its name might lead you to believe that the entire foundation is of wood, in fact only the below-grade foundation walls of a PWF that are made of wood. The base is typically a concrete slab atop a bed of crushed rock or gravel. The wood used in PWFs is pressure treated with chromated copper arsenate (CCA). The copper part of the chemical treatment provides resistance to mold, fungus, and rot while the arsenate repels ants...

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Types of Wood for Building Projects

Wood was one of the first materials ever used and it is certainly one of the longest standing. There’s evidence that homes built more than 10,000 years ago used wood as their primary construction material. But for such a well-known umbrella term, it has hundreds of varieties, classifications, and grades that make some woods better than others for certain projects. 

Understanding the types of wood, their properties, and their applications is crucial for builders. And once you understand the main types of woods, learning how they are graded will help you select the right one for your project (and fight overwhelm at the lumberyard).

Finally, understanding the components of wood strength, such as hardness, density, compression strength, bending strength (or Modulus of Rupture), and specific gravity will help you choose among the many options you might encounter for a project.

What are the three main types of wood?

Builders refer to hardwood, softwood, and engineered wood for...

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Complete Guide to Lumber Grades

The idea of lumber should be simple: it is a log that has been sawn or cut to be used for building or woodworking projects. But the specifications of lumber are myriad—it’s sold in multiple sizes, cuts, and types. Furthermore, different types of wood have different characteristics, such as density, hardness, and compression strength, which make some types of lumber better for some projects than others.

If you know the basic characteristics of lumber, choosing the right pieces for the job can be much easier—and will help you avoid the potential pitfalls of using the wrong piece of wood for the job.

4 Characteristics of Lumber

Here are four important characteristics of lumber, all key as you choose which type of to use for certain projects:

  1. Density. One physical property of wood that builders must consider in their projects is density, or the actual wood material in a unit volume of wood. Expressed in units of mass divided by volume, the higher the number the...
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Dimensional Lumber: Types, Sizes, History

The construction of buildings today would be significantly more challenging without standardized materials. If every pipe fitting, window pane, and HVAC system had to be custom designed, the time and labor involved in building even a modest bungalow would be prohibitively expensive. 

Standardization—the production of materials following uniform, industry-wide dimensions—has been crucial in allowing architects and builders to construct our modern cities, suburbs, and towns. Wood was among the first materials to undergo this process of standardization. Large timbers were transformed into a material used to build the structures of most American houses:  dimensional lumber.

What is dimensional lumber?

Dimensional lumber is cut and finished lumber (planed on all four sides) that comes in standardized sizes. These lumber sizes are typically described in inches in the United States and in millimeters in most other countries. The two numbers used to describe a piece of...

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What Is the World's Strongest Wood? Top 5 Strongest Woods

In order to find the right type of wood for every construction project, builders refer to the strength of a wood.  Different woods, classified into hardwoods and softwoods, are good for different types of projects. 

Wood strength is not given in a single measurement. It is expressed using a number of measures, such as its density (the weight per a given volume); its compressive strength (or how great a weight a load of wood can bear parallel to the grain before it ruptures); its bending strength (a load of wood perpendicular to the grain); and its hardness. 

The strength of wood fiber is very consistent across all tree species, and the strength of the wood is dependent on how many fibers are packed into a given area.  Because of this fact, a wood’s density correlates very closely to its strength and hardness.  In other words, if you know a wood’s comparative density, you can get a good approximation of its hardness and strength.  


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Wood Density Explained, Plus Wood Density Chart

For thousands of years, wood has been used for construction, and for making tools, weapons, and furniture. Most simply described, wood is the structural tissue found in the stems and roots of trees. And as you can imagine, not every wood is the same. Some types of wood are more suitable for construction than others, depending on their physical properties—which include density, texture, strength, hardness, stiffness, moisture content, potential for shrinkage, deformation, splitting, and flammability. 

There are two primary types of wood—hardwood and softwood—and both are used in different types of construction projects. The basic difference between the two classifications is not in their actual hardness. Hardwood and softwood are distinguished in terms of their reproduction: hardwood comes from deciduous trees, which produces seeds with a covering (think walnut, maple and oak); while softwood comes from gymnosperm trees, which have needles and produce cones...

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Pressure Treated Wood: Benefits, Uses, Types, Grades

Wood is a plentiful, renewable resource and one that construction crews know well. It can also, however, be difficult to maintain, especially when it is exposed to the elements.

“An option that you have with dimensional lumber is to pressure treat it. This prevents rot and fungus and bugs and other things that can destroy your material over time.” -Professional builder Jordan Smith

Benefits of pressure treated wood

Thanks to its chemical and preservative treatment, pressure treated wood is resistant to many common problems.

  • Resistance to rot. The chemical compounds used to pressure treat wood make it resistant to fungi that cause wood to rot.
  • Protection from insects. Similarly, treatments repel common insect threats like termites and carpenter ants.
  • Cost. Pressure treated wood is more expensive than untreated wood but given that it can last for decades, it often ends up being more economical in the long run.
  • Ease of Use. Pressure treated wood, like other woods, is...
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Hardwood vs. Softwood: What’s the Difference?

There are two primary categories of wood: hardwood and softwood. Both are used in different types of construction. But the difference between the two doesn’t have to do with their actual hardness or density, it’s in how the trees reproduce.

To explain it most simply, a wood is classified as a hardwood if the seeds that the tree produces have a coating in the form of a fruit or a shell. Softwoods produce seeds that don’t have a coating, which are dropped to the ground. These biological differences do impact the characteristics of the wood, which in turn impacts their uses. Read on for a complete guide to hardwoods and softwoods.

What is hardwood?

Hardwoods are angiosperm trees, or plants that produce seeds with a covering. They usually form flowers to reproduce. They’re fertilized by birds and insects that carry the pollen to other trees, and when they’re fertilized, the trees form fruits, nuts, or seeds. These types of hardwood trees include walnut,...

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