Types of Subfloors for Hardwood Flooring: In-depth Breakdown

When it comes to installing hardwood flooring, selecting the appropriate subfloor is crucial to ensure a stable and long-lasting result. A subfloor serves as the foundation, providing support and preventing moisture-related issues from damaging the hardwood flooring.

There are various types of subfloor materials, with plywood, oriented strand board (OSB), and concrete being the most common choices. Each option has its pros and cons, affecting factors such as cost, installation time, and compatibility with the hardwood flooring.

5 Types of Subfloors

There are several types of subfloors used for hardwood flooring installations. In this section, we will discuss Plywood, Oriented Strand Board (OSB), Concrete, Particleboard, and Gypsum Underlayment.


Plywood is a widely used subfloor material in residential construction. It is made by gluing together thin layers of wood, called plies, with their grains running perpendicular to each other. This arrangement provides stability and resistance to warping.

  • Thickness: 5/8″ to 3/4″ for hardwood flooring
  • Moisture resistance: Moderate
  • Strength: Good

Oriented Strand Board (OSB)

Oriented Strand Board (OSB) is another popular option for subflooring. It is a type of engineered wood, manufactured by compressing layers of wood strands with adhesives. OSB is often more cost-effective than plywood.

  • Thickness: 5/8″ to 3/4″ for hardwood flooring
  • Moisture resistance: Lower than plywood
  • Strength: Comparable to plywood


Concrete subfloors offer excellent durability and moisture resistance, making them suitable for below-grade installations like basements. However, concrete is not compatible with all types of hardwood, and an additional moisture barrier is usually needed.

High moisture resistanceRequires moisture barrier
High strengthNot compatible with all hardwood types


Particleboard is made by compressing small particles of wood with adhesives. It is less expensive than plywood and OSB but is not recommended for use as a subfloor for hardwood flooring due to its low strength and poor moisture resistance.

  • Thickness: Not applicable for hardwood flooring
  • Moisture resistance: Low
  • Strength: Poor

Gypsum Underlayment

Gypsum underlayment, a lightweight cementitious material, is often used over existing subfloors like concrete to create a smooth surface for hardwood flooring. It provides some fire resistance and sound dampening properties but is not ideal as a standalone subfloor for hardwood.

  • Thickness: Varies
  • Moisture resistance: Moderate
  • Strength: Adequate as a top layer over another subfloor

Considerations for Choosing Subfloors

When choosing a subfloor for your hardwood flooring, there are several factors to consider. In this section, we explore some key aspects, such as moisture and humidity, strength and stability, soundproofing, compatibility with hardwood flooring, and cost and installation time.

Moisture and Humidity

Hardwood flooring is susceptible to warping and deterioration due to excessive moisture and humidity. To ensure the longevity of the floor, it’s essential to select a subfloor that efficiently manages moisture, especially in areas like basements, kitchens, and bathrooms. Some popular moisture-resistant subfloor materials include plywood, oriented strand board (OSB), and cement-based boards.

Strength and Stability

A stable subfloor is particularly important for ensuring the durability of hardwood flooring. The subfloor must be able to support the weight of the flooring, furniture, and occupants of the space. Common strong and stable subfloor materials include:

  • Plywood
  • OSB
  • Concrete slabs


For multi-story buildings or living spaces where noise reduction is critical, soundproofing properties should be taken into account when choosing a subfloor. Materials offering effective soundproofing include:

  • Acoustic underlays
  • Plywood with an added layer of mass-loaded vinyl (MLV)
  • Cork underlayment

Compatibility with Hardwood Flooring

Not all subfloor materials are compatible with every type of hardwood flooring. For instance, solid hardwood flooring generally requires a plywood or OSB subfloor, while engineered hardwood flooring can also be installed on concrete slabs. Ensure that the subfloor material is compatible with your chosen hardwood floor for optimal installation and longevity.

Cost and Installation Time

Lastly, consider the cost and installation time needed for the subfloor. While costlier options like cement-based boards might offer better moisture resistance, they could also extend installation time compared to other materials like plywood. Balancing cost-effectiveness and quality is essential when choosing the right subfloor for your hardwood flooring project.

Installation Methods

There are three main methods for installing hardwood subfloors: Nail-Down, Glue-Down, and Floating. Each method has its advantages and considerations, and the best choice will depend on the specific conditions of your project.


The nail-down installation method involves fastening the subfloor to the floor joists using nails or cleats. This method provides a stable and secure foundation for the hardwood flooring, making it suitable for solid wood flooring types.

  • Typically used with 3/4″ thick solid wood planks
  • Requires a wooden subfloor (plywood or OSB)
  • Not recommended for engineered wood, as it may cause delamination


The glue-down method involves adhering the hardwood flooring directly to the subfloor using a special adhesive. This method works well for both solid and engineered wood flooring and can be used on a variety of subfloor materials.

Subfloor TypeSuitable For Glue-Down
Plywood or OSBYes
ConcreteYes (with proper moisture barrier)
Radiant Heating SystemsYes (with approved adhesive)


The floating installation method does not require fastening the hardwood flooring directly to the subfloor. Instead, the flooring is installed by interlocking the planks together, either through a click-lock system or by gluing the tongue and groove joints. This method is best suited for engineered wood flooring.

Advantages of floating installation include:

  1. Easier and faster installation
  2. Less stress on the subfloor
  3. Room for expansion and contraction due to changes in temperature and humidity
  4. Can be installed over various subfloor materials, including concrete and radiant heating systems


In summary, the selection of the appropriate subfloor for hardwood flooring is crucial for its durability and performance. Some common types of subfloors include:

  • Plywood
  • Oriented Strand Board (OSB)
  • Concrete
  • Particleboard

Each type has its pros and cons, depending on factors such as budget, installation method, and climate conditions. For instance, plywood is a stable and versatile option, while OSB provides a more economical choice.

When installing hardwood flooring on concrete, moisture control and sufficient insulation are essential. In contrast, particleboard is not recommended for hardwood installation due to its lack of structural strength.

Ultimately, choosing the right subfloor requires careful consideration of the project’s specific requirements and consultation with a flooring professional. By making an informed decision, you can ensure the longevity and performance of your hardwood floor.

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