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The BuildDirect Guide to Floor Insulation

Heating and cooling bills can put some serious stress on your finances. This is particularly true if you live in a climate that’s cold in the winter and downright blistering the rest of the year. While insulation in your walls, ceiling, attic and basement may be helping, there’s a good chance you’ve got a weak spot in your insulation scheme. Your floors.

Older homes with suspended floors are most susceptible to heat loss. Even newer homes with solid concrete floors aren’t necessarily as efficient as they should be. If you’re considering a home renovation and your goal is efficiency, floor insulation can be a smart place to start.

New building projects can benefit from floor insulation as well. In fact, adding insulation during the building process is by far the most efficient time to do it. Compared to the other costs associated with building a home, it’s also quite cost-effective.

Keep reading to learn more why installing floor insulation is so important when you’re building a new home or taking on a renovation project. You’ll also learn about R-value, different insulation styles and the basics of installation.

floor insulation

Why Install New Floor Insulation?

Floor insulation is all about efficiency and making smart choices for your home or building project. Here are six main reasons to install new floor insulation:

1. Floor insulation helps prevent heat loss through the floors.

While insulation won’t make your floors actually feel warmer – that’s typically the job of radiant heat – less warm air will escape through the floors with insulation properly installed.

2. Insulation can help keep you cool in the summer months.

It’s well-known that hot air rises. By putting a barrier between the ground beneath you and your floors, you can help keep your home comfortable even when heat loss is the last thing on your mind.

3. Insulation can help dramatically reduce drafts.

This is most important for homes that have a crawlspace or are built above the ground. By filling potential air gaps, insulation can keep air from outside from entering your home.

4. You’ll effectively create a moisture barrier between the outside world and your floors.

This is especially important if you have natural hardwood floors in your home since they’re highly susceptible to moisture changes. Adding a layer of insulation can help prevent floor boards from warping or staining your wood.

5. Insulation can help keep pipes from freezing on those ultra-cold winter days and nights.

If your home has plumbing beneath the floors, insulation can provide a little bit of extra protection against the cold.

6. Floor insulation is an improvement in uninsulated spaces like your basement or garage.

While installing full insulation and ductwork will be most effective, making major upgrades in utility spaces that you don’t spend a ton of time in may not be a wise financial choice. Adding floor insulation can help without breaking the bank in the process.

When Should I Install New Floor Insulation?

Adding new floor insulation to your home is a wise idea. Many homeowners want to know if this type of project should be undertaken at a certain time of year. The answer is yes and no.

In general, the best time to add insulation to your home is when the weather is moderate. In many regions, this time of year is the end of summer and the beginning of fall, though this may be different in your area.  Installing insulation at the most moderate time of year has a few main benefits:

•   You’ll be comfortable in your home while the insulation is being installed.

•   You’ll have insulation ready to keep your home comfortable when the cold winter weather arrives.

•   This time of year is often best for contractors and installation professionals. Sweltering mid-summer heat and cold winters can make the job harder, longer, and therefore more expensive. Even if you’re planning to do some or all of the work yourself, this time of year poses the fewest weather-related challenges.

Installing floor insulation during your region’s most moderate season makes sense if it’s the only renovation you’re taking on. If your home is currently undergoing a larger remodel or you’re mid-way through a building project, this timeframe may not apply to you.

That’s because installing floor insulation right before your finished floors go down is always the most efficient option. Many spaces require that the flooring material be removed for insulation installation if in place. This adds to the overall cost of your project, so if it’s possible, always add insulation before your flooring material is installed.

Understanding R-Value and Your Region

R-Value is a term you’ve likely seen or heard before when reading about or discussing insulation materials. In layman’s terms, R-Value pertains to resistance to heat flow. With higher R-Value comes more insulating power and reduced heat loss.

Determining what R-Value is needed for floor insulation in your home depends on your region’s climate. As of 2019, Energy Star uses a seven-zone system to help homeowners and builders determine which R-Value is correct for their project.

floor insulation climate zones
Image via greenbuildingadvisor.com

Here’s a quick breakdown of R-Value recommendations for floor insulation by zone:

  • Zones 1 and 2: R-13
  • Zone 3: R-25
  • Zones 4 and 5: R-25 to R-30
  • Zones 6 and 7: R-25 to R-30

It’s important to note that zones four and five and six and seven have similar R-Value recommendations. However, zones six and seven are colder locales with frigid winters. Many builders and homeowners choose the top end of the R-Value recommendations in this area.

Homeowners and builders in zone four and five experience cold winter weather, but lower R-Values are often an ideal balance of insulation cost and efficiency.

Need a little more help understanding R-Values for your home? Use this region map provided by Energy Star.

Should I Choose Underfloor or Under Floor-Covering Insulation?

floor insulation

You’ve decided that floor insulation might be helpful in your home. Now you need to figure where to put it, right? In most homes, underfloor or under floor-covering insulation is the ideal method. While these two methods are designed to achieve the same goal, how they’re installed is quite different.

Underfloor Installation

Underfloor installation is a term commonly used when insulation can be placed beneath your floor without pulling up wood planks or any type of floor covering you may have. For this installation style to work, you’ll generally need access to a crawlspace under your floors. If you do have this access, installing insulation is a relatively simple process.

Under Floor-Covering Installation

Homes that don’t have access to a crawlspace under the floors often utilize under floor-covering insulation. For this method, you’ll need to remove your existing flooring to place your insulation. Typically, mineral wool or glass fiber insulation is held in place by mesh netting is placed before your finished floors go back down. Foam insulation may be used in some cases.

Under floor-covering insulation is typically a more expensive and time-consuming process than underfloor insulation. However, if it is your only option, it can greatly improve heat loss in your home while remaining cost-effective for homeowners and builders.

Insulation Materials Used for Flooring

Insulating your floor generally means you’ll be working with one of two materials: fiberglass or rigid foam insulation. These two materials have unique benefits and drawbacks when used as flooring insulation material.

Unless you’ve got years of DIY experience, having a professional install flooring insulation is typically recommended. A contractor may also be able to guide your DIY installation and supervise or help with the more complicated elements of your project.

Even if you do hire a pro, you’ll still need to know about the different installation materials used so you can make the right choice for your home. Here’s a quick primer on the two commonly-used floor insulation materials:

Fiberglass Insulation

Fiberglass is a popular pick for homeowners and builders when it comes to floor insulation. Here are the pros and cons:


  • Fiberglass is cost-effective. It can cost half as much as rigid foam.
  • Fiberglass is lightweight. If you’re taking on a DIY renovation, this can be an important factor.
  • Cutting fiberglass is a relatively easy process, making it a material that’s easy to work with.


  • Fiberglass material can compress over time, making it less effective.
  • This material won’t protect against moisture particularly well. This is a consideration if you live in a very wet climate, having piping in your floors or are installing insulation above a basement. Fiberglass may not be best option under materials like hardwood that can easily warp, either.
  • Working with fiberglass requires protective equipment. Made up of many glass fibers, you’ll need a respirator, protective clothing and safety goggles to use fiberglass.

Rigid Foam Insulation

Rigid foam insulation is another popular choice for floors. Here are the main pros and cons to consider before installing rigid foam insulation:


  • Rigid foam insulation won’t compress or warp over time like fiberglass.
  • Rigid foam is rejects moisture, making it an ideal choice for floors like natural hardwood that could warp, mold or stain.
  • You can use rigid foam insulation with a radiant heat flooring system. This can help give you the warmest flooring possible under-foot.


  • Rigid foam is more expensive than fiberglass and can cost up to 50% more.
  • Rigid foam is difficult to work with compared to fiberglass since it is much less flexible.

Insulating your floors is an ideal way to make your home more comfortable and energy efficient. In the case of hardwood and other materials that can stain or warp due to moisture, insulation can also provide protection. That same protection extends to plumbing beneath your floors.

Want to learn more about installing fiberglass or rigid foam floor insulation as part of your building or renovation project? Reach out to us today so we can learn more about your specific needs.

Our trained advisors can guide you toward the right insulation style and help you get the materials you need to start your project whether you’re doing the job yourself or hiring outside help.