Can you lay hardwood directly on a subfloor?

Author: Makayla Hagenes DDS  |  Last update: Saturday, October 18, 2025

Most engineered flooring can be installed using staples, full spread adhesive or a floating method over an approved subfloor. Make sure you have a sturdy subfloor: 3/4-inch CDX plywood is preferred and 3/4-inch OSB is acceptable.

What should I put between subfloor and hardwood?

Underlayment is a thin layer of padding—usually foam, rubber, felt, or similar material—placed beneath hardwood floors. It serves multiple purposes, the biggest of which is moisture protection.

How do you prep a subfloor for hardwood floors?

Prepare the subfloor

Preparing the subfloor is a critical step, especially for the glue down or nail down methods. Sand down the surface to remove any materials. Vacuum up the remnants, and then dispose of them. If there are any squeaky spots, securely screw the subfloor into the floor joists.

Do you really need underlayment for hardwood floors?

Wood floors are not as soft as cork options, providing little comfort as you walk through the home. An underlayment, though, will provide a small level of cushioning, creating a softer floor that you are sure to enjoy for years to come.

What should I put down before installing hardwood floors?

Select an underlayment suitable for your wood flooring type. The underlayment can provide a moisture barrier, sound insulation, and cushioning. The moisture barrier is of utmost importance, as concrete will naturally emit moisture in the form of vapor.

Can I Install A New Hardwood Over An Old One?

Does hardwood go directly on the subfloor?

wood subfloor. Most engineered flooring can be installed using staples, full spread adhesive or a floating method over an approved subfloor. Make sure you have a sturdy subfloor: 3/4-inch CDX plywood is preferred and 3/4-inch OSB is acceptable.

How to level a plywood subfloor before installing hardwood?

Thoroughly vacuum the existing floor, and use a long floor leveler and tape measure to ensure the subfloor is level within 3/16 inch for every 10 feet. You'll need to know how to level a floor: Just sand any high spots and fill the low spots with leveling compound.

What is the best underlayment for hardwood floors on wood subfloor?

What is the Best Underlayment for Hardwood Floors? Felt is used as underlayment for hardwood floors. It forms a hard surface without making the planks wet, which can cause them to warp. Cork is also a good choice, as it resists moisture and supports heavy loads on wood.

Is a moisture barrier necessary for wood floors?

For these traditional installation methods, the need for an underlayment can vary. A moisture barrier, while not always necessary, can provide extra protection. If you choose to use rosin paper, this can help prevent squeaks and offer minor resistance to moisture.

Can you lay wood floor without underlay?

Wood floors are perfectly comfortable to walk on without the need for extra padding underneath, and the subfloor will have to be made even before installation – so underlay isn't required there.

Can I put flooring directly on subfloor?

Most modern vinyl flooring, such as Happy Feet, comes with an attached underlayment or pad, often with a moisture barrier built-in – unless the pad is cork. If the product you choose doesn't have an attached underlayment, you can almost always install directly over the subfloor without one.

How thick should subfloor be for hardwood floors?

The minimum thickness of plywood for subflooring is about 5/8 inch. Since it does not hold fasteners as well as plywood, OSB must be a little thicker, or at least 23/32 inch. There are several factors that determine what subfloor thickness is optimal for added benefits like insulation.

How to start hardwood flooring straight?

Don't start directly against the wall.

Most walls aren't perfectly straight so you risk ending up with a less than perfect installation. Make a mark on the wall at both ends of the room where you will place your first row. This will give you a reference point for where the whole planks should start and end.

Why put paper under hardwood flooring?

But it's still commonly used and if you speak with builders or wood flooring installers or architects, you hear all sorts of reasons for the purpose of this paper: It prevents floor squeaks. It's a vapor barrier. It cuts down on dust.

How flat does the subfloor need to be for hardwood?

Most experts agree that the maximum tolerance for a subfloor is 3/16” over a ten-foot span. Any dips or mounds exceeding this measurement need to be addressed before installation.

Do I need a vapor barrier over a wood subfloor?

When moisture penetrates your flooring, it can cause mold, mildew, and the potential for water damage. A moisture barrier helps control the water vapor's movement to help protect your floors. Therefore, if you're installing floors in an area that sees moisture, even a little, a vapor barrier is needed.

Should you put anything under hardwood flooring?

It is beneficial to install hardwood floors with an underlayment. Despite the slight increase in cost and time, the added protection will benefit your floor long-term by reducing moisture. Additionally, increasing noise and evening out minor subfloor flaws without requiring substantial rework.

What is the best moisture barrier for subfloor?

Moisture and mold protection

An underlayment that offers a vapor barrier is essential to protect any flooring installed over a subfloor that emits moisture, like concrete. A thin foam underlayment made of polyethylene or polypropylene usually works best.

Should you use pressure treated wood for subfloor?

Should I Use Treated Plywood for Subflooring? Using treated plywood for subflooring is generally unnecessary since the wood will be completely covered and hidden from access.

Do you need wax paper under hardwood?

Is wax paper required? No, it is not required to lay wax paper between subfloor and the hardwood. Warranties are the same either way. Touchwood Flooring recommends the use of wax paper as it reduces moisture transfer from wood to subfloor and vice versa.

How do you level a subfloor for hardwood flooring?

Pour the liquid-like floor leveler onto the subfloor and smooth it out with a trowel. Gravity will help it settle into the low areas. Remove any excess floor leveler and feather it around the edges so it blends with the rest of the floor. Let the floor leveler dry overnight or as indicated by the manufacturer.

Can you lay hardwood directly on subfloor?

Hardwood flooring is best installed over a plywood subfloor rather than particleboard. Particleboard can expand and contract with moisture changes, potentially causing hardwood to buckle or warp. Installing plywood provides a stable, moisture-resistant base for hardwood.

What goes between hardwood floor and subfloor?

You have the top layer that is your floor covering (Hardwood, Laminate, Vinyl, Carpet, etc.), next you have the underlayment (usually a thin layer of fiber, foam, rubber), below that you have your subfloor (plywood, OSB, concrete), and lastly you have the joists which are the foundation to your floors.

Does subfloor need to be perfectly level?

No subfloor is perfectly level, but any signs of unevenness and high or low spots must be remedied. Please follow these requirements: Subfloor unevenness cannot be greater than 3/16 of an inch over a 10-foot span or 1/8 inch over a 6-foot span.

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