Does Drywall Have an R-Value?

By Mike

April 20, 2021

Are you paying too much on your heating bills? Or have you just started constructing your walls and want to avoid this problem. Insulation is the key here.

Insulation is important in every home. Investing in the proper type of insulation for your house pays back in the future reducing a lot of your energy bills and providing more comfort for you and your family.

Drywall now is in every house. It’s easy to use to create walls and even design features. Some use it for insulation. Yes, drywall has an R-value of 0.45 for its ½ inch thickness. This is a relatively low R-value compared to other wall materials. Does it help resist heat flow? And is it enough on its own?

In this article, we’ll talk about the meaning of R-values, the use of drywall as an insulator, as well as the best types of insulation to use with drywall.

How Does Insulation Work?

If you’re not convinced that you need to insulate your drywall, let me explain to you how insulation works. Heat moves from warmer areas to cooler areas until there’s no longer a temperature difference.

This means that in the winter, heat moves from your house to a cooler place which is outdoors. It can move through any open space like a crack in the window or the door jambs. The opposite happens in the summer. Heat moves from the outside into your house.

The heat lost in winter is replaced by your heating system. And your cooling system helps remove the heat gained in the summer. Insulation resists the heat flow and therefore decreases it.

What Does R-Value Mean?

R-value stands for Resistance value. It measures the thermal resistance of different materials. In other words, it indicates the material’s capacity to resist the flow of heat and cold.

In the building industry, R-values are used to measure the effectiveness of insulating materials. The higher the R-value the better the insulator. The R-value of an insulator depends on its material, its thickness, and its density.

R-values increase with the thickness of the insulator. Also, R-values are additive. This means that if you attach a material with R-value 12 to another with R-value 1, the measured R-value you get from adding both is 13.

The amount of insulation you need for your house varies depending on several factors. This includes the climate, which part of the house you need to insulate, and the heating or cooling system you’re using.

Does Drywall Have an R-Value?

Yes, drywall has an R-value of 0.45 for its ½ inch thickness. This is a relatively low R-value compared to other wall materials. For instance, ½ inch thickness of plywood has an R-value of 0.63, and fiberglass batt of 3 1⁄₂ inch thickness has an R-value of 11.0.

Drywall is a good construction material for interior walls for so many reasons, but it’s not primarily used to insulate. That’s why you need to install insulation behind your drywall.

Usually, drywall is positioned against insulation on the outer layers. This makes it an effective air barrier. But, the main reason why drywall is used in this case is its superior fire resistance property.

Some wall insulators are flammable like cellulose or batt insulation. It’s recommended to always check the description of the material you’re using for insulation. If the wall material you’re using isn’t flammable, you can leave it without covering it with drywall.

However, drywall adds extra R-value and a great look to your walls. Using drywall as a finishing layer for your insulation makes it easier to add electrical outlets. It’s a lot easier to hide the wires behind the drywall layer.

Do I Have to Insulate Drywall?

As mentioned above, the drywall itself doesn’t have much of a capacity to resist heat or cold. So, if you’re looking to properly insulate your house, it’s better to insulate your drywalls.

You can skip the step of insulating your drywalls, but this will cost a lot in the future. Insulation can save you a lot of money by reducing your energy bills.

Think about it this way. If you decide not to insulate your walls to save money, as a result, you’ll have to pay more expensive bills throughout the next few years. However, investing in added insulation will decrease your energy bills in the future saving you a lot of money.

Another advantage of insulating your drywall is slowing the spread of fire. Fortunately, most of the insulation materials we install today are fire-rated materials. This means that they’re designed to burn slowly.

Insulating drywall can also help in soundproofing. It doesn’t completely block the sound. But, it definitely will help to shut off the noise of traffic and construction outside.

What Are the Best Types of Insulation to Install Behind Drywall?

Now that you know the importance of insulation, it’s time to know the best options to use with drywall. The best types of insulation to use with drywall are fiberglass batts, spray foam, and loose-fill cellulose.

  • Fiberglass is the one commonly used in houses and it’s the cheapest. This is best installed during the construction phase of the wall. It can also be used when replacing the existing drywall.

    If you’re trying to be more environmentally conscious, maybe fiberglass isn’t your best option. It’s a non-combustible material. Fiberglass doesn’t need additional fire-retardant chemical treatments as it’s already a fire-rated wall material.

SmartSHIELD -3mm 24"x50Ft Reflective Insulation roll, Foam Core Radiant Barrier, Thermal Insulation Shield, Commercial Grade (24"x50')

  • Expandable spray foam is a good option, especially for exterior walls. Foam has a higher R-value of 3.6 to 4.0 per inch. It also stands up to moisture better than fiberglass batts.

Touch n' Seal High Density Spray Foam Roof Insulation Kit 3.0 PCF Closed Cell Foam - 120 BF

Last, but not least is loose-fill cellulose. It makes it possible to insulate existing drywall. Cellulose is a completely eco-friendly option. It’s made of recycled newspaper that is highly combustible.

Final Thoughts

Whether you’re constructing a new house or replacing your old drywall. You need to check the costs and the benefits of the materials you’ll be using for insulation. I also recommend checking their payback periods.

Don’t forget to check the Department of energy’s recommendation about insulation. This can help you a lot with the whole process.

About the author

Hi I'm Mike! I'm the owner, writer, and sometimes editor of Foundedproject.com. Being a new homeowner can be a little daunting, which is why I created this blog. I write about problems that a new home owner might run into. 

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