Hardwood Guide: Types, Grades, and Uses for Flooring

Choosing hard wood for your floors is one of the most consequential decisions you will make during a renovation. The species you select determines how your floors look, how they resist dents and scratches, how long they last, and what you will pay. With dozens of domestic and exotic species available, plus multiple grading systems and finish options, the choices can feel overwhelming. This guide breaks it all down so you can buy with confidence.

Hardwood vs. Softwood: What Is the Difference?

The distinction between hardwood and softwood is botanical, not necessarily about literal hardness. Hardwoods come from deciduous (leaf-shedding) trees like oak, maple, walnut, and hickory. Softwoods come from conifers like pine, fir, and cedar. Most hardwoods are physically harder than softwoods, but there are exceptions — balsa is a hardwood that is softer than most pines, while heart pine is a softwood that rivals oak in hardness.

For flooring, hardness matters because it determines how well the wood resists dents, scratches, and wear from foot traffic. The Janka hardness scale measures the force required to embed a steel ball halfway into the wood surface. Higher numbers mean harder, more durable floors.

Popular Hardwood Species for Flooring

Each species brings a distinct grain pattern, color range, and hardness level. Here are the most common choices for residential flooring:

• Red oak — Janka rating 1,290; the most popular flooring species in America with pronounced grain and warm reddish-pink tones; $3 to $6 per square foot unfinished
• White oak — Janka rating 1,360; tighter grain than red oak with golden-brown color; naturally water-resistant due to closed pores; $4 to $8 per square foot
• Hickory — Janka rating 1,820; extremely hard with dramatic color variation from blonde to dark brown; $4 to $7 per square foot
• Hard maple — Janka rating 1,450; light, uniform color ideal for contemporary spaces; $5 to $9 per square foot
• American walnut — Janka rating 1,010; rich chocolate brown tones; softer than oak but prized for its beauty; $6 to $12 per square foot
• Brazilian cherry (jatoba) — Janka rating 2,350; extremely hard exotic with deep reddish-orange color; $7 to $14 per square foot

Understanding Hardwood Grades

Hardwood flooring is graded by appearance, not structural strength. The National Wood Flooring Association (NWFA) uses these standard grades:

Clear Grade (Select)

The most uniform boards with minimal color variation, no knots, and consistent grain. This is the premium grade and the most expensive, typically commanding a 20% to 40% premium over lower grades.

Select and Better

Mostly clear boards with minor natural character marks. Some slight color variation is acceptable. This grade offers a clean look at a lower price than pure clear grade.

Number 1 Common (Character Grade)

Boards show visible color variation, small knots, and natural character marks. This grade is increasingly popular because it looks more natural and organic. It costs 15% to 25% less than clear grade.

Number 2 Common (Rustic Grade)

Heavy character with large knots, mineral streaks, and significant color variation. Rustic hard wood floors have surged in popularity for farmhouse and industrial aesthetics. This is the most affordable grade.

Solid vs. Engineered Hardwood

Solid hardwood is milled from a single piece of timber, typically 3/4-inch thick. It can be sanded and refinished multiple times over its lifespan — typically 5 to 7 refinishing cycles — making it a true lifetime flooring investment. The drawback is sensitivity to moisture and humidity changes, which cause expansion, contraction, and potential cupping or gapping.

Engineered hardwood layers a real wood veneer (1/16 to 1/4 inch thick) over a plywood or HDF core. The cross-grain construction resists expansion and contraction far better than solid wood, making it suitable for below-grade basements, concrete subfloors, and radiant heat systems where solid hardwood cannot go. High-quality engineered hardwood with a thick wear layer can be sanded 1 to 3 times.

Finish Options

Pre-finished hardwood arrives from the factory with the stain and protective coating already applied. The finish is cured with UV light or aluminum oxide, making it harder and more scratch-resistant than anything applied on-site. The trade-off is visible micro-bevels at each board edge that collect dirt over time.

Site-finished hardwood is installed raw and then sanded, stained, and sealed on location. This produces a seamless, flat surface with no visible board edges. Water-based polyurethane is the most popular site-applied finish — it dries clear, has low odor, and cures in 24 to 48 hours. Oil-based polyurethane adds a warm amber tone that deepens over time but takes 3 to 5 days to fully cure.

Installation Methods

How hard wood flooring gets installed depends on the product type and subfloor material:

• Nail-down — solid hardwood is blind-nailed through the tongue into a plywood or OSB subfloor using a pneumatic flooring nailer; labor costs $4 to $8 per square foot
• Glue-down — engineered hardwood adhered directly to concrete or plywood with urethane adhesive; labor costs $3 to $6 per square foot
• Floating — engineered planks click together and sit on an underlayment without fasteners; the easiest DIY method at $1.50 to $3 per square foot in labor savings

Maintaining Hardwood Floors

Proper maintenance extends the life of any hardwood floor by decades. Sweep or vacuum with a soft-bristle attachment 2 to 3 times per week to remove grit that acts like sandpaper underfoot. Damp-mop weekly with a hardwood-specific cleaner like Bona or Murphy Oil Soap — never use steam mops, wet Swiffers, or vinegar-water solutions on finished hardwood.

Place felt pads under all furniture legs and replace them every 6 months. Use mats at exterior doors to catch grit and moisture before it reaches the wood. Maintain indoor humidity between 35% and 55% year-round with a humidifier in winter and dehumidifier in summer to minimize seasonal expansion and contraction.