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Can You Use OSB for Attic Flooring? (How To)

House attic

When considering flooring options for your attic, you may wonder if Oriented Strand Board (OSB) is a suitable choice. OSB is an engineered wood product made from compressed wood strands and adhesive, often used in construction projects for its cost-effectiveness and durability. In this article, we’ll discuss the feasibility of using OSB as attic flooring and guide you through the process.

First, you’ll need to determine if your attic can support the added weight of OSB flooring. Access your attic and thoroughly inspect the condition of the trusses or joists, considering factors like spacing and the overall structural integrity. If you’re uncertain, consult a professional engineer or contractor to ensure your attic is capable of handling the additional load.

Next, we will discuss the advantages and drawbacks of using OSB as attic flooring material, focusing on aspects such as insulation, moisture resistance, and load-bearing capacity. By the end of this article, you’ll have the information necessary to make an informed decision about whether OSB is the right choice for your attic flooring project.

What is OSB?

Empty house attic

Oriented Strand Board (OSB) is an engineered wood product, created by compressing layers of wood strands together with adhesives. This process results in a strong and versatile building material that can be used for a variety of construction projects, including attic flooring.

One of the main benefits of using OSB for your attic flooring is its cost-effectiveness. Compared to plywood, OSB is generally more affordable while still providing adequate strength and durability for most attic floor installations.

Additionally, OSB is available in large panel sizes, making it more efficient for covering large areas of your attic floor. This can help you save time and effort during the installation process.

However, it’s important to consider the moisture resistance of OSB when using it for attic flooring. While this material is less prone to warping compared to traditional plywood, it is still susceptible to moisture damage if not properly protected or installed in highly humid environments.

To help mitigate moisture concerns, consider using an OSB product with a moisture-resistant treatment or adding a layer of moisture barrier beneath your OSB attic floor. This way, you can ensure the longevity of your flooring project and keep your attic space safe and functional.

Pros and Cons of Using OSB for Attic Flooring

House attic construction


  • Cost-Effective: OSB is typically less expensive than plywood or other flooring materials, making it an attractive option for your attic flooring project.
  • Durability: OSB is engineered to be strong and consistent, helping to ensure a stable and reliable surface for your attic floor.
  • Easy Installation: Installing OSB is relatively simple, requiring only basic tools and skills. You can quickly cut and fit the panels as needed.


  • Moisture Sensitivity: OSB can be more susceptible to moisture damage compared to other materials like plywood. You should avoid using OSB in areas with high humidity or potential for water leaks.
  • Lack of Aesthetic Appeal: Unlike hardwood or laminate flooring, OSB is not typically chosen for its visual appeal. However, you can always cover it with more attractive materials if desired.
  • Potential for Formaldehyde: Some OSB products contain formaldehyde, which can off-gas into your living space. To avoid this issue, opt for formaldehyde-free OSB when selecting your attic flooring material.

Preparation Before Installing OSB in Attic

Remodel house attic

Measuring and Planning

Before installing OSB boards for attic flooring, taking accurate measurements is crucial. Measure the dimensions of your attic space using a tape measure. Note those dimensions down and calculate the area in square feet. This will help you determine how much OSB you need.

Next, plan the layout and orientation of your OSB boards. Make sure the seams between boards will land evenly on the floor joists. Try to avoid narrow, small pieces in high-traffic areas to ensure stability and longevity. To make cutting and fitting easier, draw out a blueprint that illustrates the layout plan.

Choosing the Right Thickness

Selecting the proper thickness of OSB is essential for attic flooring. OSB boards come in various thicknesses, commonly ranging from 7/16 inch to 3/4 inch. Consider your attic’s intended use to choose the suitable thickness.

For storage or infrequent access, 1/2 inch thick boards may suffice. However, if you plan to use the space more regularly or want added durability, go for 5/8 inch or 3/4 inch thick OSB boards.

Keep in mind that local building codes may specify certain thickness requirements. Be sure to comply with these regulations in your area.

OSB Thickness

Suitable Usage

1/2 inch

Light storage

5/8 inch

Regular usage

Copyright protected content owner: and was initially posted on May 31, 2023.

3/4 inch

Heavy usage, durability

Once you’ve measured and chosen the right thickness, you’re ready to purchase the OSB boards and gather installation materials. By properly preparing, you’re on your way to successfully installing OSB attic flooring.

Installation Process

Attic construction area

Tools and Materials Needed

To install OSB for attic flooring, you will need the following tools and materials:

  • OSB (Oriented Strand Board) sheets
  • Tape measure
  • Circular saw or table saw
  • Hammer or nail gun
  • Nails or screws
  • Safety goggles and gloves
  • Chalk line or straight edge
  • Carpenter’s square
  • Drill (optional for pre-drilling holes)

Laying Down OSB Sheets

  1. Begin by measuring the area of your attic to determine the number of OSB sheets you’ll need. Remember to account for any space around entries, pipes, or vents.
  2. Before installing the OSB sheets, check for any protruding nails, screws, or debris that may get in the way of laying the OSB sheets flat. Clear the area if needed.
  3. Start in one corner of the attic and lay the first sheet of OSB. Align the edges of the OSB sheet with the attic floor joists, leaving a 1/8-inch gap between the OSB sheet’s edges and the walls.
  4. Mark any required cuts on the OSB sheets using a tape measure, carpenter’s square, and chalk line or straight edge. Wear safety goggles and gloves, and use a circular saw or table saw to make the necessary cuts.

Securing OSB in Place

  1. Once the OSB sheets are in position, secure them to the attic floor joists using a hammer and nails or a nail gun with nails. Alternatively, you may use a drill and screws. Space fasteners 6 inches apart along the edges of the sheet and 12 inches apart in the field (the middle area of the sheet).
  2. Stagger the seams of the OSB sheets to ensure a more robust and stable attic flooring. Avoid aligning the seams in a straight line across the attic, as this can create a weak point in the floor.
  3. After securing the first sheet, continue laying down and securing the rest of the OSB sheets in the attic, making sure to maintain the 1/8-inch gap between sheets as well as between the sheets and walls.
  4. Work systematically across the attic, and remember to account for any unique features or obstacles in your space.

By following these steps, you will successfully install OSB for your attic flooring.

Copyright article owner is for this article. This post was first published on May 31, 2023.

Alternative Attic Flooring Options

Wood planks


Plywood is a popular choice for attic flooring due to its durability and affordability. To install plywood in your attic, first measure the space where you want to install the flooring. Choose plywood with a thickness of at least 3/4-inch for optimal strength. Cut the plywood to fit the space, and lay it across the floor joists. Be sure to stagger the seams for added stability. Secure the plywood with screws, ensuring it is level and well-supported by the joists.

Tongue and Groove Boards

Tongue and groove boards can provide a more finished look to your attic flooring. This type of flooring consists of boards that have a groove along one side and a tongue along the other, allowing them to fit snugly together. To install:

  1. Measure your attic space and purchase enough boards to cover the area.
  2. Start in one corner, laying the first board along the edge with the groove facing inwards.
  3. Place the tongue of the next board into the groove of the first board, ensuring a tight fit.
  4. Continue installing the boards along the row, and then proceed to the next row, working your way across the attic.

Make sure to leave a small gap around the perimeter for expansion.

Insulated Tiles

For added insulation and comfort, you can consider using insulated tiles for your attic flooring. These tiles are lightweight and easy to install. They come in various sizes and can be easily cut to fit your attic space. To install:

  1. Measure your attic and determine how many tiles you will need.
  2. Start in one corner, laying the first tile with the interlocking edges facing towards the rest of the room.
  3. Connect the next tile by aligning the interlocking edges and pressing down firmly until the tiles lock together.
  4. Continue placing tiles until your attic floor is covered.

Remember to trim your tiles as needed to fit around obstacles or to fit snugly against the walls.

By considering these alternative attic flooring options, you can find the best solution for your specific needs, transforming your attic into a functional space.

Top Takeaways

Cutting OSB board

Using OSB for attic flooring is a practical and cost-effective solution for homeowners who want to add extra storage space or create a more functional attic. OSB is a strong and durable material that can withstand the weight of typical storage items and foot traffic. The following are the top takeaways on the topic of using OSB for attic flooring:

  1. OSB is a cost-effective option: In comparison to alternatives like plywood, OSB (Oriented Strand Board) is an affordable choice for attic flooring. This can be especially appealing when working on a tight budget or covering a large area.
  2. Opt for a higher thickness: Durable and sturdy attic flooring requires a thickness of at least 5/8-inch or 3/4-inch OSB. This will ensure your attic floor has enough strength to support your weight and stored items.
  3. Consider humidity and moisture resistance: OSB can be susceptible to humidity and moisture damage over time. Choose OSB materials that are treated to be moisture resistant and check your attic’s ventilation regularly.
  4. Proper installation is crucial: Properly install OSB boards by staggering seams, maintaining a 1/8-inch gap for expansion, and using screws specifically designed for OSB. This ensures a long-lasting and secure attic floor.
  5. Not suitable for heavy storage: Although OSB is strong enough for light storage and occasional access, it may not be suitable for storing heavy items or continuing heavy foot traffic. In those cases, plywood flooring may be a better option.
  6. Code compliance matters: Before using OSB for attic flooring, ensure you are respecting local building codes, permits, and regulations. Each municipality has its own requirements, so it’s important to be aware of them.
  7. Check load-bearing capacity: Before installing OSB, evaluate your attic’s weight-bearing capacity. Attic structures are generally designed to support minimal loads, so make sure your attic construction is suitable for an OSB flooring installation.
  8. Efficient use of resources: OSB is an environmentally-friendly choice, as it utilizes small, fast-growing trees and waste materials (such as sawdust and chips) from larger trees to make a functional product. By using OSB, you contribute to responsible forest management.

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ReadyToDIY is the owner of this article. This post was published on May 31, 2023.

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