Softwood and hardwood are the most common used expressions used in the wood market. Hardwoods are graded for use aesthetically vs structurally. Softwoods are typically graded and applied structurally. They're interchangeable for some applications, but generally that is depending on your project and the engineer.
Hardwoods are perceived as stronger than softwoods, but softwood is used more often structurally because its more affordable than hardwood. There's no reason why hardwood can't be used structurally, but it is rarely milled into structural shaped lumber, and doing so is very costly. Because of this and several other factors generally the most common use for hardwood outside of furniture and cabinet making is large blocking pieces used for cribbing, crane mats and skids. Hardwood crane mats are most common on the eastern side of the US where hardwoods are more prevalent vs Douglas fir crane mats on the west coast where hardwood is harder to find, but depending on your project and location the strength of these mats are comparable.
Traditionally, trailer decking has been hardwood lumber to resist the dents, dings and weight on heavy machinery. As the availability of hardwood lumber goes down the cost goes up. So in places like California where the weather is milder you can get away with Douglas fir as a decking material as it is very strong compared to its softwood relatives. You may have to replace a piece every few years but at the cost of decking lumber such as Apitong, you could almost replace the deck 5 times before you have reached the cost of a hardwood deck.
Crane mats are known throughout construction as a common product used to support equipment in ‘sticky situations.’ Depending on your location, equipment being used, and your budget Hardwood vs Douglas Fir crane mats are interchangeable in most cases. Hardwood is not always stronger than the softwood in some situations. Sometimes elasticity, weight, ecological regulations and even rot resistance can change from jobsite to jobsite, therefore the performance on these materials can change. Environmental differences can also alter the woods performance. So ‘harder wood’ does not always mean better.
Fir, pine, spruce and hemlock are the main sources of framing lumber. Framing lumber is the main go-to lumber for framing and building structures. These woods are often a combination and sometimes marketed generically as Hem-fir, hem-fir-spruce, or even spruce-pine-fir. When lumber is grouped like this, it's been graded for structural performance. It's a common practice and there's no worry about mixing it up. However, when they are sold individually they can be graded differently. It is always best to clear the different options with the customer.
Douglas fir is rated as one of the strongest of the softwood varieties. It actually rivals some of the hardwoods for strength. It's the best all-around lumber for studs and beams. It can be more expensive than other varieties when singled out, but also has many advantages and is easier to find when you need custom sizing cuts. It can also be stained and finished as trim. Although it lacks distinct grain patterns this allows you to blend it with other materials without standing out as a patch.
Hemlock is straight-grained and light, but typically not used as often as Douglas fir. It's used more often for moldings and trim because it resists warping and twisting, and when stained, reflects more pronounced grain patterns than other softwoods. Hemlock has only moderate resistance to scratching and dents, and is not as readily available in some areas.
Pine is the not as strong as fir or hemlock. Pine has more knots, but it's more affordable than hemlock or fir. Pine has the advantage of aesthetics if you like rustic lumber for paneling, cabinets or furniture. It's only real disadvantage is that it's one of the weakest woods out there, and can be prone to warping and twisting.
Redwood, cedar and cypress are three softwoods with natural weather-resistance. They share structural properties with fir, but are more appropriate for decking, trim, and all exterior applications when aesthetics and weathering are factored in. Although Douglas fir can be used in these applications successfully as long as a paint or sealer is used to protect the lumber.
Redwood could be considered the gold standard for outdoor application. It's got everything: beauty, strength and it lasts a lifetime. Use it for decking, stair and banister railings, decorative borders or anything else when only the best will do. Redwood has two major disadvantages: it's very expensive -- and it's listed as an endangered species.
Cedar shares weather-resistant qualities with redwood, but is slightly cheaper. It's lightweight and strong. Use it for all kinds of exterior trim, fences, shingles and siding. Drawbacks include it's softness -- it dents and scratches very easily. Many varieties of Cedar are also naturally pest resistant.
Oak, maple, walnut, cherry, birch and alder are commonly compared domestic hardwoods used in fine furniture and cabinets. Oak and eucalyptus are most commonly used for industrial applications such as cribbing, Crane Mats and pipe skids. Apitong is the prefered hardwood for decking, but limited availability has risen the cost segnificantly, so the new aalternative offered is Purple Heart.
Oak has the tradition of strength and beauty. It's broad, flame-like patterns are easily recognized. It's priced mid-range for a hardwood, and available everywhere but tends to b much more difficult to find in large quantities on the west coast. Drawbacks include, oak can be hard to work with, and shatters and splinters easily if it's not cut with sharp, carbide-tipped blades, and it warps, checks and cracks quickly. High grades are use it for cabinets, furniture, doors and interior trim, leaving lower grades for blocking and cribbing.
The exotic Apitong can be very difficult to find. Smaller dimensions like 2” and 3” thick decking boards are the most common but can still take months before suppliers have the lengths you need. Due to its hardness, it is very difficult to cut and that is why most people order it precut to length.
A recent option used as a replacement for many hardwood projects as it is more readily available than some other species. However, it generally ships from the south/south-east and unless ordered in large quantities can get expensive very quickly.
Basic Grading & Descriptions for common Species;
Redwood (Sequoia sempervirens)
Oregon White Oak (Quercus garryana)