How To Install Hardwood Floors Directly Over Joists

Installing hardwood floors directly over joists can be a cost-effective and efficient option for homeowners looking to enhance their living space. This method allows for a faster installation process while showcasing the natural beauty of hardwood. However, it’s essential to understand the nuances of this approach to ensure a successful outcome. From the condition of the joists to the thickness of the boards, various factors can influence the durability and aesthetics of your floor. In this guide, we’ll explore everything you need to know about installing hardwood floors over joists, including tips for optimal installation, potential challenges, and considerations for maintaining a comfortable and inviting environment.

What Are Floors Made Of?

Let’s take a quick look at the structure of floors in general:

1. Joists: The foundation of any flooring system, joists are critical structural elements that support the entire weight of the floor above. They are typically made of wood or engineered lumber and span the distance between walls, forming a sturdy base. All houses have joists, except those built on a concrete slab.

2. Subfloor: Installed directly on top of the joists, the subfloor adds overall stability and plays a vital role in moisture protection. It is usually constructed from plywood or oriented strand board (OSB), providing a solid surface for the finish flooring to rest upon. Properly installed subfloors help to minimize movement and prevent creaking noises.

3. Underlay: This layer is essential only for floating installations—a fitting method where planks or boards are attached by snapping, gluing, or nailing them together without securing them to the subfloor. An underlay can also be beneficial for all types of wooden flooring, offering added cushioning, sound insulation, heat retention, and moisture protection.

4. Finish or Top Floor: This is the visible surface where daily activities take place. It can consist of various materials, including solid hardwood, engineered wood, parquet, laminate, or vinyl. The choice of finish impacts the aesthetic appeal, durability, and maintenance of the floor.

This is the typical structure of a floor. However, you might wonder: Is it possible to install our finish floor directly over the joists without a subfloor in between?

Wood Floor Fitting Over Joists

To answer the question directly: Yes, it is entirely possible to install hardwood flooring directly on top of the joists. Both solid wood and engineered wood can be fitted using this method. However, there are important considerations to keep in mind regarding the spacing of your joists.

• Joist Spacing: In general, joists should not be more than 45 cm (18 inches) apart. If the spacing exceeds this distance, additional support is necessary to ensure the stability of the flooring. You can achieve this by using noggins (small horizontal pieces of wood) and braces for reinforcement. Alternatively, you can install a plywood or oriented strand board (OSB) subfloor before laying down the top flooring.

Why Installing a Subfloor is Beneficial

While it is feasible to install flooring directly over joists, having a subfloor is generally a better approach for several reasons:

1. Improved Insulation: A subfloor helps limit the effects of drafts and moisture, enhancing the overall comfort of your home.

2. Enhanced Stability: It provides a more stable base for your finish floor, reducing the risk of movement and noise.

3. Easier Installation: Any additional fixing or installation work will be much simpler on a subfloor, as it creates a uniform surface to work with.

4. Flexibility with Joist Spacing: With a subfloor in place, you don’t have to worry about the maximum spacing between joists, allowing for more flexibility in your floor design.

In summary, while installing hardwood flooring directly over joists is possible, using a subfloor is highly recommended for enhanced durability, stability, and ease of installation.

Few Tips on What You Should Consider

The Joists

The condition of your joists is the most important factor when considering direct installation. Ensure that they are:

• Stable: Joists should be structurally sound to support the flooring.
• Relatively Dry: Check for any signs of moisture. If your joists are damp, identify the source of the moisture to prevent future issues.
• Properly Levelled: Uneven joists can lead to problems with the flooring above.

If you suspect potential moisture problems, it's advisable to avoid fitting directly over the joists. Instead, consider installing a proper subfloor, which can absorb excess moisture and protect your finish floor. Pairing a subfloor with a good underlayment will enhance the longevity and appearance of your top flooring layer.

The Boards

Keep in mind that a subfloor helps distribute weight evenly across the flooring. Without it, the pressure on the planks or boards increases. To ensure adequate support, choose boards that are thick enough to handle this pressure. We recommend:

• Thickness: No less than 20 mm
• Length: Approximately 6 ft for hardwood flooring

Noise

Noise is a crucial detail that many homeowners overlook. If you install flooring directly over joists—especially on the second floor—sound insulation will be minimal. This means every sound and footstep will be audible. If privacy is a concern, particularly in areas like bedrooms, you might want to reconsider this installation method.

Underfloor heating

The absence of a proper subfloor doesn’t eliminate the option of using underfloor heating, especially if you're using engineered hardwood. The heating system can be effectively installed between the joists, providing warmth without compromising the flooring structure.