Is Drywall Required Under Tongue and Groove? (Explained)

Applying tongue and groove walls is a popular way to give your home a rustic look. It’s a simple project that most DIY’ers can handle on their own. However, there is some debate about whether or not Drywall is required under the Tongue and Groove before applying the final coat of paint or varnish.

Drywall under Tongue and groove is not a local building code requirement. However, it’s common practice and highly recommended as it would give you a smooth finish and help with fire resistance and soundproofing.

You might have heard of people saying you don’t need Drywall under Tongue and groove, while others would swear that it must be installed. The truth is, the answer is more of a preference than being compliant with building code requirements. 

Do I Need to Install Drywall Under Tongue and Groove?

Using Drywall under the Tongue and Groove is not actually a local building code requirement. So, legally, you don’t have to install sheetrock under the Tongue and groove. That being said, hanging the Drywall for safety is highly recommended.

Drywall is made of gypsum – a non-combustible mineral. So, this wall-covering material will provide fire resistance to some degree. Moreover, the Tongue and groove don’t provide a continuous surface, so using Drywall might help inhibit infiltration and exfiltration.

Although it’s not a requirement, most builders recommend installing Drywall under the Tongue and groove – especially if there’s a chance of fire break. Drywall will protect your building by slowing down the fire, as a wooden ceiling is nothing more than fuel.

Pros Of Installing Drywall Under Tongue And Groove

The most significant benefit of this practice is that it increases your home value. In addition, it improves safety and protects you from fire hazards. And if you’ve read the article where we discuss how to install J Molding on Drywall, you would be able to use this technique to make a very smooth transition, making it very aesthetically pleasing.

Here are some of the practical advantages of installing Drywall under the Tongue and groove:


Tongue and groove are wood panels made of cedar, spruce, or pine. So they will catch on fire easily and quickly. To reduce fired damage, your best bet is to use a Drywall between the Tongue and Groove and the actual ceiling. In some cases, you can also Drywall over Wood Panels to increase fire resistance.

Drywall sheets are non-combustible that can resist fire to some degree. In addition, you can even buy one-hour fire-rated drywall panels, aka Type X drywall. With this approach, you can protect your property from a fire. But in some circumstances, you can also go for a 1/2-inch Drywall.


Installing Drywall under the Tongue and Groove can also help with certain types of sounds, including a radio playing and people talking. It’s recommended to use 5/8-inch Type X drywall to reduce damage. This variation might be a little expensive, but it’s worth every single penny.

The 5/8-inch Drywall is commonly used for soundproofing a commercial property, but this doesn’t mean you cannot use 1/2-inch Drywalls for commercial purposes. However, you can use it for residential properties as well. You can even use insulation materials (soft foam or fiberglass) to get better resistance to heat flow.

Smooth Finish

Drywall is one of the most popular wall-covering materials because it allows you to attain a smooth surface when installed correctly. By installing Drywall under the Tongue and groove, you can eliminate imperfections and gaps, allowing you to attain an even surface easily.

Cons Of Installing Drywall Under Tongue And Groove

Installing Drywall under the Tongue and groove is additional work. As no building code requires you to perform this action, you’ll be spending extra time and money. 

Plus, drywalling a ceiling is not actually a piece of cake. In fact, it’s considered one of the most difficult parts of a home renovation project. If not done properly, the Drywall might result in cracks or failure. On top of that, if you decided to use regular 1/2-inch Drywall, you might end up sagging, which then means you’d need to redo the whole thing. Luckily there is a difference between ceiling Drywall and regular to counter that.

The Tongue and groove are basically wood. So, it’ll catch on fire instantly. It might even compromise the quality of Drywall, allowing the fire to reach the actual ceiling quickly. Therefore, if you have fire-related concerns, ensure your Type X drywall is under the Tongue and groove.

What Else Can I Put Under Tongue and Groove?

While installing Tongue and groove over a concrete surface, an underlayment is critical to prevent moisture from seeping through between the flooring and the concrete. Otherwise, the flooring will become prone to leaks and lead to mold growth.

If, for some reason, you don’t want to use Drywall under Tongue and groove, you can pick any of the following building boards as an underlayment for Tongue and groove:


Plywood is the most commonly used material under the Tongue and groove. This material offers more stability and strength. It might be a little more expensive than Drywall, but it has a higher R-value and is more durable.

Instead of using a plywood board under Tongue and groove, it’s advised to get Tongue and board plywood. With this approach, you don’t need to buy separate panels. It creates a more-rigid, stronger subfloor and helps eliminate sagging. 


If the fire is your biggest concern, using fiberboard under the Tongue and groove is a better option. Fiberboard is the most expensive and durable type of building board available on the market. It provides higher resistance to heat flow and moisture.

Fiberboard is constructed using synthetic resin and wood that has been reduced to a fibrous state. You can even get tongue-and-groove fiber cement boards for outdoor projects. 


Do I Need Drywall on Ceiling?

It’s advised to install Drywall on the ceiling because it’s basically fireproof. Even regular drywall panels resist fire to some degree. Moreover, compared to other alternatives, drywalling a ceiling is cheaper, lasts for a long time, and offers a smoother surface after finishing!

Can I Put Tongue and Groove Over Drywall?

Yes, you can install Tongue and groove over the existing Drywall. This approach will help you reboot the atmosphere in your bedroom or living room. Furthermore, sheetrock’s fire resistance balances the wood’s propensity to burn, making the room much safer than wood alone.

Should I Glue Tongue and Groove Boards?

You should never glue tongue and groove boards. This is because the room dimensions change due to extraction and contraction. So, if you glue Tongue and groove, there’ll be no room for movement, leading to warping, disfigurement, and cracks.

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