Is Alder a Hardwood or a Softwood? (& Is It Strong?)

Is Alder a Hardwood or a Softwood? (& Is It Strong?)

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If you are looking to build something around your home, whether floors, walls, furniture, cabinets, or anything in between, choosing the right type of wood is essential. Now, one popular type of wood used in North America is alder.

With that being said, whether this material is a hardwood or softwood is something that confuses many people, because it is in fact quite soft, yet is classified as a hardwood. Let’s figure out whether alder is a hardwood or a softwood, and just how strong it actually is.

Is Alder a Hardwood or a Softwood?

Alder is a very common type of hardwood tree that grows in the Pacific Northwest, both in the USA and Canada. This tree is technically a type of hardwood, as it is a part of the angiosperm tree family, and it is deciduous in nature, which means that it does lose its leaves during the colder seasons.

What is interesting to note is that although alder is classified as a hardwood, it is actually relatively soft, one of the softest hardwoods out there, and even softer than many types of softwood. This wood has a low bending strength, compressive strength, stiffness, hardness, density, and more. Alder is a very soft hardwood.

Alder Wood Strength

Although we did mention that alder is a very soft type of hardwood, we do want to take a closer look at just how strong it really is. The strength of wood can generally be determined by examining five main factors. These factors include compressive strength, bending strength, stiffness, hardness, and density.

Now, there are a few different types of alder that are commonly used for construction. These include red alder, Nepalese alder, and European alder, so we will be taking a closer look at all three of these today. Let’s get to it and figure out just how strong alder is.

Compressive Strength

Below, we have listed the compressive strengths of the three main types of alder that you might be familiar with:

  • Red alder – 5,820 lbf per square inch (40.1 MPa)
  • Nepalese alder – 4,900 lbf per square inch (33.8 MPa)
  • European alder – 5,770 lbf per square inch (39.8 MPa)

The compressive strength of wood, which is otherwise known as the crushing strength, refers to how much of a load it can take parallel to the grain. In other words, this is in regard to how much weight a piece of wood can hold vertically before it buckles.

As you can see, Nepalese alder has the lowest compressive strength, whereas red alder has the highest.

That said, alder is relatively weak. We can compare this to mahogany, with swamp mahogany having a compressive strength of 8,540 lbf per square inch. We then have other types of wood, such as eastern red cedar, which has a compressive strength of 6,020 lbf per square inch, and even ebony, which has a compressive strength of 11,060 lbf per square inch.

Bending Strength

Below, we have listed the bending strengths or modulus of ruptures for the three main types of alder being reviewed today:

  • Red alder – 9,800 lbf per square inch (67.6 MPa)
  • Nepalese alder – 7,400 lbf per square inch (51 MPa)
  • European alder – 13,260 lbf per square inch (91.4 MPa)

The bending strength of wood is otherwise known as the modulus of rupture. This refers to the load that a piece of wood can take perpendicular to the grain, as opposed to compressive strength, which as we mentioned before, measures parallel to the grain.

We can then compare this to other types of wood, such as the western red cedar, which features a bending strength of 7,500 lbf per square inch. There are then much weaker types of wood, such as balsa, which has a bending strength of 2,840 lbf per square inch.

There are also much stronger types of wood, such as swamp mahogany, which has a bending strength of 17,490 lbf per square inch, or even Gaboon ebony, which has a bending strength of 22,930 lbf per square inch.

Stiffness

Here we have listed the stiffness ratings for the three main types of alder that we are looking at in this review:

  • Red alder – 1,380,000 lbf per square inch (9.52 GPa)
  • Nepalese alder – 1,200,000 lbf per square inch (8.28 GPa)
  • European alder – 1,596,000 lbf per square inch (11.01 GPa)

We then have the stiffness of wood, which is also referred to as the modulus of elasticity. In the simplest terms, this refers to how much weight it takes for a piece of wood to bend when weight is placed in the middle of the wood.

In other words, this is in reference to how much a piece of wood will bend when a load is placed perpendicular to the grain. This is important for things like flooring because you need to know how much a piece of wood is going to bend if you step on it.

As you can see, European alder is the stiffest of these three types of wood. However, in general, alder is not extremely stiff. We can compare this to other types of wood, such as swamp mahogany, which has a stiffness rating of 2,047,000 lbf per square inch.

Yes, wood such as balsa is much weaker, as it can handle only 538,000 lbf per square inch before it starts to bend. However, we then have much stronger types of wood, such as Gaboon ebony, that can handle up to two 2,449,000 lbf per square inch before bending occurs.

Hardness

Here we have listed the hardness ratings for the three main types of alder wood that we are reviewing today:

  • Red alder – 590 lbf
  • Nepalese alder – 380 lbf
  • European alder – 650 lbf

The hardness of wood refers to how hard the surface of a piece of wood is. In other words, this is a measurement of how resistant a piece of wood is to physical impacts, denting, and scratching. This is measured on the Janka hardness scale.

The hardest of these types of wood is European alder, although even this is still very soft. For comparison, Douglas fir features a hardness rating of 620 lbf, eastern red cedar has a Janka hardness rating of 900 lbf, and Gaboon ebony has a rating of 3,080 lbf. In the grand scheme of things, alder is very soft.

Density

Here we have listed the densities or weights of the three main types of alder wood that you might be familiar with:

  • Red alder – 28 lbs per cubic foot (450 kg per cubic meter)
  • Nepalese alder – 31.3 lbs per cubic foot (500 kg per cubic meter)
  • European alder – 33.3 lbs per cubic foot (535 kg per cubic meter)

The density of wood is the fifth main factor that we want to examine when determining how strong a piece of wood is. This refers to how heavy a piece of wood is in regard to a specific size, and this is generally measured in either kilograms per cubic meter or pounds per cubic foot.

When it comes down to it, across the board, alder is one of the lightest types of wood around. Douglas fir weighs about the same as Nepalese alder, with Gaboon ebony being much heavier than all types of alder, which is also the case for all types of mahogany.

Is Alder Strong?

In the grand scheme of things, no, alder is not very strong. Yes, it works well for smaller pieces, decorative items, lightweight furniture, cabinets, and other such things. However, it’s definitely not something that you should use for structural soundness, as it just can’t hold a whole lot of weight, it’s not very hard, and it does bend fairly easily.

Summary

Now that you know everything there is to know about alder wood, you can make an informed decision in terms of whether or not this is the right type of lumber for you to use.