Fir and pine are both conifers, and they both produce softwoods. But in some respects, they’re very different. So, how exactly do fir and pine lumber compare with each other?
True fir lumber (Hem-Fir) has an excellent stiffness-to-weight ratio. Douglas-fir is stiff and strong, with excellent dimensional stability. Southern Yellow Pine is hard, dense wood with an excellent strength-to-weight ratio, while other pines are lighter and weaker.
Because there are so many pine species and the confusion between true firs and Douglas-fir, it can be a challenge to distinguish between fir and pine lumber.
What Is Fir Lumber?
Fir lumber is commonly sold in three different ways in the US, and only one of these is likely to have much true fir in it, although it’s just as possible not to have any.
Let’s clear up possible confusion. SPF (spruce-pine-fir) is a mixture of species with similar characteristics mainly sourced from Canadian forests. Some are true fir; some are Western yellow pine; much of it is spruce.
Hem-Fir (hemlock-fir) is a mixture of Western hemlock and true firs. There’s also Douglas-fir. So what are true firs and Douglas-fir?
True firs are species in the genus Abies, in the pine family (Pinaceae). The genus has about 50 species, occurring all over the Northern Hemisphere in mountainous areas.
They are large trees, growing from 30 to 260 feet tall when mature. They are in the same family as pines, but their needles grow singly on the branches with bases like suction cups.
On the other hand, Douglas-fir is a species in its own genus, Pseudotsuga, in the pine family. It is also known as Oregon pine and Douglas spruce, but it isn’t fir, pine, or spruce. Instead, its closest relatives are among the larches.
It is sometimes called Doug fir and may be sold under DF-L, standing for Douglas-fir-larch.
Depending on subspecies, they grow anything from 70 to 330 feet tall when they are mature. Their needles also grow singly, like firs, and they have incredibly thick, corky bark, making them exceptionally fire-resistant.
What Is Pine Lumber?
Pine lumber is sourced from species in the genus Pinus, in the family Pinaceae. The genus contains about 120 species, most of which are trees.
The needles are arranged in bundles called fascicles, with anything from one to seven needles per fascicle. Most pines have two to five needles per fascicle, with the number of needles being one of the characteristics used to classify pines.
Woodworkers classify them into soft pines (white pines) and hard pines, subdivided into four groups: Southern yellow pines, Western yellow pines, red pines, and pinyon pines.
Only the soft pines and the two groups of yellow pines are of economic importance in the US so we will restrict our description to these pines.
How Are Fir And Pine Lumber Different?
Now that we’ve considered what fir and pine are let’s examine the differences between the various types of lumber sold in the trade.
Because of how woods are sold in the US, you may sometimes not be sure of getting a particular species, so we have to speak in general terms.
Characteristics Of Douglas-fir Lumber
Douglas-fir is a hard and heavy softwood, with a Janka hardness of 620, and is stiff and strong for its weight, with a modulus of rupture of 12,500 and a modulus of elasticity of 1,765,000. It has excellent dimensional stability. Its average dried weight is 32 pounds per cubic foot.
It is generally light reddish-brown, with a straight or slightly wavy grain and a moderately coarse texture. Flatsawn pieces can show wild grain patterns, typically seen in veneers. It has resin canals, like pine, but unlike true firs.
Douglas-fir is moderately rot-resistant but vulnerable to insect attack. The wood machines well and holds nails well. It takes stains and glues well and is easy to finish.
It is widely available as construction lumber and is moderately priced, although old-growth lumber is considerably more expensive. Woodworkers have made furniture with this wood.
You may find it stamped DF-L.
Characteristics Of Hem-Fir Lumber
Many species of fir have excellent stiffness-to-weight ratios. Grand fir, a representative species of the white fir group, has a Janka hardness of 490, a modulus of rupture of 8,740, and a modulus of elasticity of 1,530,000. Its average dried weight is 28 pounds per cubic foot.
The wood is pale, from nearly white to a straw color, with a straight grain and a somewhat coarse texture.
Fir wood is not resistant to rot or insects. It is easy to work and glues, stains, and finishes well. It takes pressure treatment well and has excellent wear resistance.
Botanists divide fir into different groupings, with the primary species in the western United States all belonging to the white fir group. Hemlock has a similar color, grain, and weight. Neither of these two genera has resin canals, distinguishing them from pine.
They are usually sold together as Hem-Fir at moderate prices for use as construction lumber.
Characteristics Of Southern Yellow Pine Lumber
The primary species in this group (Shortleaf, Longleaf, Slash, and Loblolly Pine) have hard, dense wood. Shortleaf Pine has an average dried weight of 35 pounds per cubic foot and a Janka hardness of 690.
They have an excellent strength-to-weight ratio, with Shortleaf Pine having a modulus of rupture of 13,100 and a modulus of elasticity of 1,750,000.
The wood has a fine texture and a straight, uneven grain, with large resin canals. The sapwood is pale yellow; the heartwood reddish-brown.
The wood is only slightly rot and insect resistant. It works well, although the resin can clog sandpaper and cutters. It glues and finishes nicely.
It is used for construction lumber, railroad ties, bridges and is relatively moderately priced. It is often used for wooden roller-coasters and is sought after for furniture.
Characteristics Of Western Yellow Pine Lumber
Western yellow pine is lighter in weight than Southern yellow pine, with a more even grain.
The two main species (Ponderosa Pine and Lodgepole Pine) are so similar that construction lumber is stamped PP/LP, and the two species are not distinguished.
Lodgepole Pine has an average dried weight of 29 pounds per cubic foot and a Janka hardness of 480. Its modulus of rupture is 9,400, and its modulus of elasticity is 1,340,000.
Sapwood is pale yellow; heartwood is light brown and not demarcated from the sapwood. Flatsawn surfaces show dimpling vaguely reminiscent of birdseye maple. The grain is straight, and the texture medium, with numerous medium-sized resin canals.
It doesn’t have much rot or insect resistance. It works well, glues well, and finishes nicely.
Western yellow pine is widely available as construction lumber (stamped PP/LP) for moderate prices. It is used for plywood, crates, boxes, sheathing, and sub-flooring, among other uses.
Characteristics Of White Pine Lumber
As a representative of this group, Sugar Pine has an average dried weight of 25 pounds per cubic foot and a Janka hardness of 380.
The lumber of white pine is lighter and weaker than Southern yellow pine but has outstanding dimensional stability.
Sugar pine’s modulus of rupture is 8,200, and its modulus of elasticity is 1,190,000.
The wood is straight-grained with a reasonably coarse texture and large resin canals. Heartwood is light brown; sapwood is very pale (almost white).
The wood does not resist rot or insects. It is easy to work, glues and finishes nicely, and is used for construction lumber, crates, and boxes. White pine is moderately highly-priced.
Characteristics Of SPF Lumber
The ‘ultimate mystery meat of woods,’ as one frustrated woodworker dubbed it, SPF (spruce-pine-fir), is a combination of different woods with similar characteristics.
It is generally very light in color, lightweight, and easy to work with. It is generally not nearly as strong as Southern Yellow Pine. Beyond that, it is impossible to generalize.
It is used for construction lumber, crates, and pallets.
While fir and pine have characteristics in common, both being softwoods in the pine family, they are also different. True fir lumber has an excellent stiffness-to-weight ratio, while Douglas-fir is stiff and strong, with excellent dimensional stability.
Southern Yellow Pine is hard and dense with an excellent strength-to-weight ratio, while other pines are lighter and weaker, although white pine has outstanding dimensional stability. None of the woods are resistant to rot or insects, but true fir takes pressure treatment well.