What Is the Best Insulation for Under Floors?

No one likes it when they step out of their warm, cozy bed in the morning, only to put their little toes on extremely cold flooring. Many people don’t like sleeping in socks, and if your floors don’t have quality insulation, that morning chill can creep into your floors and make for a very unpleasant wake-up call.

Insulation is important for your flooring for many reasons. If you live in a colder climate, it makes it more comfortable. However, even people who live in warmer climates want insulation too. So, let’s dive into the world of insulation and see what option will work best for you, your floors, and your lifestyle.

Why Should I Insulate My Floors?

Great question! Insulating your home is important for many reasons. While most people think about insulating their walls, ceilings, and attics, your floors need to be insulated as well. Why? 

First and foremost, Insulation helps with energy efficiency. Insulated floors help to keep heat and cool in areas that are temperature controlled from those that are not — like your attic and your basement. This keeps your energy bills lower all year round.

Insulation also helps with sound control. It can help to reduce the sounds of heavy walkers, children, pets, and more. If you have a workout room in your home, teenagers who play instruments, or just want a quieter space, it’s imperative to insulate your floors.

Additionally, insulation helps to control moisture. Cooking, bathing, doing the laundry, and more add moisture into the air, which can get trapped in your flooring. When it gets trapped, it eventually can turn to mold and mildew, which both present health concerns. Insulation and underlayments on your flooring can help to provide a barrier to this moisture which is a win-win all the way around.

Types of Insulation

We tend to use the term “insulation” as a catch-all, but there are actually different types of insulation that can be used in different applications.

The first step you want to take to choose the best insulation for your floors is to determine what type of insulation has already been used in your home. Builders tend to use the best insulation for the area, the best sizing, and the best application.

It can be hard to find insulation without breaking something, so you should start by looking in your attic. There is almost always some visible there if you haven’t covered it with boxes and other stored items.

It depends on many different things, but these are the most common types of insulation used with flooring:

Roll Insulation

Roll insulation is a good type of flooring insulation because it comes in a wide, puffy sheet that can be cut to fit your flooring. It is great for use in attic flooring, and it goes over the joists.

One word of caution: be sure to use protection because all roll insulation is made out of glass fibers.

Batting Insulation

Batting insulation is great to put under crawlspaces and joists, particularly in attics. The one problem with flooring is that it cannot be flattened, so you will need to have some clearance space. Just like roll insulation, this comes in long strips made out of glass fibers.

Blown-In Insulation

 Blown-in insulation is a loose cellulose or fiberglass insulation that is good for attics and walls. It is not recommended for use under floors except in extreme situations.

Spray Insulation

Spray insulation is the easiest insulation to use. It is a great option for around windows and in door frames when you need insulation. It can go under the floor, but it isn’t the best option. It will take a long time and a lot of work to use spray insulation under floors, and there are just better options out there.

Rigid Foam Insulation

Another good option for some types of hardwood flooring, rigid foam insulation comes in sheets of polystyrene. It is great to tuck under floors because it provides a partial vapor barrier and protects the floor from some water damage.

The Insulation Application Matters

Let’s say that you want to install some beautiful new bamboo flooring in your living room. But where do you start? First, you want to install the insulation. You need to approach installation in a very particular manner. First, you want to eliminate all existing insulation. By pulling up the flooring, you are disturbing that insulation, and there’s no real way to know what condition it’s in at this point.

The best approach is to put down your insulation first. Be sure to add some extra support around door frames and windows. Cover the ground completely to reduce moisture. Be sure to seal the rim joist and crawl space vents, which will help to keep your home warmer in the winter and eliminate those cold feet.

Be sure not to use a moisture barrier that is going to trap the moisture in the insulation. This can increase the chance of rot and mildew.

Where To Install Insulation

If you are looking to make your home more energy-efficient, you want to add insulation in as many places as you can, including under your floors. If you aren’t installing that new bamboo floor but rather just working on your home, here are some other areas to try:

  • Attic Flooring - if you have flooring in your attic, you should add some insulation.
  • Basement Flooring - check the rim joists and flooring to find the R-value and then replace or add insulation.
  • Crawlspace Flooring - this space may seem small, but you want to ensure the floor joists are vented and cover the floor with a polyethylene sheet.
  • Exterior Floors - insulating this can help prevent cold air and moisture from creeping into your home.
  • Garage - Garage floorings should be insulated if possible.
  • Knee Walls - Insulating your floors is a great chance to also insulate knee walls, which are the walls between living spaces and spaces that are temperature controlled like the garage.

Remove Insulation That Gets Wet

Moisture is your biggest enemy. So, it’s important to remove any insulation that gets wet. If you have a leak in your dishwasher or washing machine, your toilet overflows, or you have a fire, and they use water to put it out, you need to check if your insulation has gotten wet. While it may seem annoying to pull up a small piece of board to check, insulation can get mold and rot. Not only is this bad to breathe in, but it can actually smell bad and attract pests.

Insulating Your Floors Is a Great Idea

No one wants cold feet in the morning (or anytime!), and sometimes slippers just aren’t an option. And what’s even worse than cold feet? Paying energy bills that you could lessen. By insulating your floors, you are fixing small things that plague you every day and big things that plague you on a monthly basis. It’s clearly a smart move!

Our only caution: you have to be careful when installing insulation. So, if you don’t know what you are doing and you aren’t willing to do the research, you may want to leave it up to professionals — which is never a bad idea.

No matter which route you choose, you can never go wrong with insulating your beautiful floors. It will make your home comfier, and your feet will definitely thank you!

Sources:

Where to Insulate in a Home | Energy.gov

How to Insulate Existing Floors | Home Guides

Types of Insulation | Energy.gov

Calculating R-value | University of Calgary 

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