Home Improvement Interior Remodel Flooring & Stairs

What Is Tongue and Groove Flooring?

Hardwood Floor Installation
Jeffrey Zavitski/E+/Getty Images

Tongue and groove flooring is wood flooring that's quite durable and easy to install because the floorboards are all fitted with a protruding (tongue) and concave (groove) parts that fit together like puzzle pieces. All four sides of the floorboards have tongues and grooves.

The process of joining tongue and groove materials has been around for many years. This simple method seams together two boards, typically floorboards, in a way that holds them together while allowing for some flexibility during and after installation.

Tongue and groove are often used in conjunction with wood floorboards, sheet paneling, wainscot, and any number of other materials where a tight, solid seam is required between separate pieces.

One tongue fits firmly into the groove of the adjoining board. The purpose is to control vertical movement between adjoining boards. Horizontal movement is still allowed to a small degree and is a desirable quality since wood flooring will expand and contract. 

Fun Fact

With the invention of the side matcher, a machine that turns wooden planks into floorboards, the first hardwood tongue and groove flooring was created in 1885.

Pros & Cons of Tongue and Groove Flooring

Advantages

  • Tight seams: Tongue and groove floors feature tight seams, requiring a minimal amount of nailing or gluing to hold the boards together.
  • Water-tight: With proper coating, tongue and groove can even be water-tight. This applies to site-finished flooring, not pre-finished.
  • Lower cost: Products that are made for tongue and groove installation are less expensive than other floor options. Tongue and groove installation does not include patented technology or other specialized manufacturing methods to create the product.

Disadvantages

  • Tough to fit: It can be difficult to fit the tongue into grooves, especially with boards that have become swollen due to humidity.
  • Breakage: The tongues can easily break off unless special care is taken.
  • Permanent: It's difficult, if not impossible, to disassemble floorboards that have been joined with tongue and groove. Tongue and groove wood floors usually cannot be taken apart without significant breakage.

Tongue and Groove vs. Lock and Fold Flooring

When choosing flooring, you will have two installation methods: tongue and groove and lock and fold. Basic tongue and groove joinery is a straight tongue that horizontally slides into a straight groove. To prevent the boards from moving, boards can be glued down and nails or flooring staples are driven into the tongues. These fasteners attach directly to the subfloor. Tongue and groove could be better for more permanent installations.

An easier, faster, and increasingly popular method, lock and fold (also called click lock), was developed for laminate flooring and engineered wood installation. This method does not require glue, nails, or staples to attach the boards to the subfloor and is considered a floating floor. Floating floors attach only to themselves, from one board to the next, not the sub-floor. The lock-and-fold method allows the tongues to fit into the grooves by angling one board onto the adjoining board and then folding it downward to lock it in place.

Lock and fold gives you the option of removing the boards for replacement or repairs. It also moves much less than tongue and groove products. There's still room for some microscopic horizontal movement, but nowhere near the type of movement allowed by classic tongue and groove. 

How to Install Tongue and Groove Floors

You can install tongue and groove floors by fastening boards down or both gluing and fastening them down. Here are a few tips:

  • Nails can be better than staples, especially for thicker tongues. But floor staples can lessen the chances of splitting the wood and each staple has two legs to add stability.
  • Install the first course of boards to the wall shimmed for space to allow some expansion and contraction around the edges. The base trim will hide any gaps.
  • Use a flooring nailer or flooring stapler to nail through the tongue of each board, not on the face of the board. The fasteners will be hidden after the installation is complete.
  • You will need the proper flooring nailer, flooring stapler, nails, or staples for the thickness of the boards.
  • Always follow the flooring manufacturer's instructions on spacing nails or staples.
FAQ
  • Does tongue and groove flooring need underlay?

    Yes. Underlayment reduces the development of boards squeaking and moving. This is especially important in rooms, such as bedrooms, where a quiet floor is important.

  • How do you secure tongue and groove flooring?

    Construction glue, nails, or staples are used to secure the boards to the subfloor. In some older or antique homes, there may not be a subfloor, and tongue and groove flooring can be attached to joists. (Floating floors need a subfloor for installation.)

  • How much does tongue and groove flooring cost?

    In general, tongue and groove flooring is cheaper to buy than lock and fold flooring. However, the professional labor costs are higher for tongue and groove flooring than for floating floors. If you are doing a DIY tongue and groove flooring, you may need to order more flooring for potential fitting issues.

  • Is it hard to install tongue and groove flooring?

    Though installing tongue and groove flooring can be a DIY project, you will need a lot more time and patience to fit, glue, and then fasten down the boards than needed with lock and fold systems.