Preparing Your Subfloor for Solid Wood Flooring Installation

Installing solid wood flooring is an investment in lasting beauty and durability — but it all starts with the subfloor. No matter how high-quality your wood planks are, they can only perform well if the base beneath them is properly prepared.

Subfloor preparation is the foundation of a successful installation. It affects how the flooring feels underfoot, how long it lasts, and whether problems like creaking, warping, or gaps appear down the line. In this guide, we’ll walk you through each step to get your subfloor ready for solid wood flooring, ensuring flawless results from day one.

Why Subfloor Prep Matters for Solid Wood Floors

Solid wood flooring is a natural product that reacts to its environment — expanding and contracting with changes in moisture and temperature. Unlike engineered wood, it’s less forgiving when laid over an uneven, damp, or unstable subfloor.

Without proper preparation, you risk a range of problems, including:

• Creaking and movement: Caused by uneven or poorly fixed subfloors.
• Gapping or buckling: Due to hidden moisture or lack of expansion space.
• Reduced lifespan: Flooring may wear out faster or need early repair.

That’s why solid wood flooring should never be installed over a flawed base. A smooth, level, dry, and clean subfloor is essential for a high-quality, long-lasting result.

Step 1: Check the Subfloor Type

Before anything else, identify what kind of subfloor you're working with — this determines your installation method and preparation steps. Solid wood flooring must always be fixed down (nailed or glued), so floating installation is not suitable.

• Timber Subfloors (e.g. plywood or existing floorboards): These are ideal for nail-down installation. Ensure the boards are secure, even, and free from rot or damage. You may need to add plywood sheets to create a smooth surface.
• Concrete Subfloors: Suitable for glue-down installation, but require more attention to moisture and flatness. You’ll need to test the moisture level and potentially apply a damp proof membrane (DPM).

Each subfloor type has its own requirements, so knowing what you’re working with is the first step toward a successful fitting.

Step 2: Ensure the Subfloor Is Dry

Moisture is one of the biggest enemies of solid wood flooring. If your subfloor isn’t dry enough before installation, the boards can absorb moisture, leading to cupping, warping, or swelling over time.

• For Timber Subfloors: Use a wood moisture meter to check that the moisture content is below 12%.
• For Concrete Subfloors: Use a concrete moisture meter or hygrometer. Readings should be below 4% before you proceed with glue-down installation.
• Apply a Damp Proof Membrane (DPM): If moisture levels are borderline or you're unsure, it's wise to install a surface DPM. This barrier prevents any residual or future moisture from reaching the wood.

Skipping this step can lead to expensive repairs down the line. Always test and document moisture levels before fitting begins.

Step 3: Make Sure the Subfloor Is Flat and Level

Solid wood planks require a stable, even surface to sit properly. An uneven subfloor can cause boards to move, creak, or even crack over time. That’s why levelling the surface is a crucial part of preparation.

• Tolerance Limit: Your subfloor should have no more than 3mm deviation over a 1-meter span. Anything more can cause issues with board alignment and long-term stability.
• Timber Subfloors: Use plywood sheets or hardboard overlays to level out any dips or imperfections.
• Concrete Subfloors: Apply a self-levelling compound to smooth out bumps, hollows, or uneven patches.

Before proceeding, walk across the room and check for any soft spots or height variations. Fix them now to avoid much bigger problems later.

Step 4: Clean and Prime the Surface

Once the subfloor is dry and level, it’s time to prepare the surface for bonding. A clean, dust-free surface ensures that adhesives work effectively and that the boards sit flat and secure.

• Remove Debris: Sweep or vacuum the subfloor thoroughly to eliminate dust, grit, or any leftover adhesive from old flooring.
• Check for Oil or Grease: On concrete, clean any spills with a degreaser — contaminants can prevent adhesive from bonding properly.
• Prime If Gluing: If you're using a glue-down method on a concrete subfloor, apply a suitable primer before the adhesive. This improves grip and controls absorbency.

A well-prepared surface ensures maximum adhesion, minimises movement, and provides a solid foundation for a long-lasting floor installation.

Step 5: Allow for Acclimatisation

Before installation begins, solid wood flooring needs time to adjust to the environment where it will be laid. This step, called acclimatisation, allows the boards to equalise their moisture content with the room and reduces the risk of future movement or warping.

• Leave the Flooring in the Room: Store the sealed boxes in the room where the floor will be installed for 7 to 14 days.
• Lay Them Flat: Stack the packs flat and open the ends slightly to allow air circulation.
• Maintain a Stable Environment: Ensure normal living conditions — ideally 18–22°C temperature and 40–60% relative humidity.

Skipping this step is one of the most common causes of post-installation issues like gaps, buckling, or cupping. Give the wood time to settle — it’s worth the wait.

Need Quality Solid Wood Flooring?

Once your subfloor is fully prepared, it’s time to choose flooring that lives up to the effort. We offer a wide selection of solid wood floors in a variety of species, finishes, and sizes — perfect for traditional or contemporary interiors.

If you’re unsure which type of solid wood is best for your project, or you need installation advice, get in touch with our expert team — we’re here to help.

Conclusion

Solid wood flooring adds unmatched warmth and elegance to any space — but its performance depends on what's beneath it. Taking the time to properly prepare your subfloor ensures a smooth, stable, and long-lasting installation.

From checking moisture levels to levelling and acclimatisation, every step plays a role in preventing costly issues like gaps, squeaks, or movement. Explore our solid wood flooring collection today, or contact our team if you need guidance on preparing your space for a flawless fit.