Crawl space insulation is a great way to improve your home’s energy efficiency and comfort.
Without proper crawl space insulation, you may feel your home’s floor is too cold in winter or too warm during summer.
Insulating a crawl space might seem like a daunting task, but with the proper equipment and basic knowledge, you can complete the job quickly and efficiently.
In this guide, we’ll tell you how to insulate a crawl space. We’ll go through everything from why it’s important to insulate a crawl space to the different types of insulation.
Insulating your crawl space is significant for your home’s comfort and energy efficiency.
For instance, insulating concrete crawl space walls and floors help keep your home warm in winter. That’s because insulation reduces heat loss and helps your home retain heat better in winter and stay cooler in summer.
Moreover, it aids in preventing your crawl space from becoming a breeding ground for mold and bacteria.
Note that your crawl space isn’t like a finished floor. It’s likely only gravel and soil. As such, extra moisture and humidity can ruin your crawl space by turning it into a suitable place for bacteria and mildew to thrive.
Also, insulation can help deter pests, rodents, and insects from inhabiting the area beneath your house. That’s because insulation materials are usually unappealing to pests, providing an extra protection barrier.
On top of that, crawl space insulation makes your home more energy efficient by reducing energy consumption, leading to lower electricity bills. Potential buyers also appreciate lower energy consumption and extra comfort. So decent insulation can be a selling point.
There are two main types of crawl spaces for homes; ventilated and unventilated. Each has specific insulation requirements, but one thing is for sure; as your home gets older, you’ll need to replace the insulation.
There are several ways to tell if your crawl space needs new insulation. Let’s look at the signs that your crawl space needs insulation.
If you notice your floor is unusually warm during summer or cold in winter, it could be an indication that your crawl space doesn’t have proper insulation.
As your home ages, insulation deteriorates and creates unprotected areas. These areas allow air to move freely between the crawl space and your living area, which disrupts your heating and cooling systems.
In these cases, adding extra insulation can do the trick, however, in most scenarios, replacing the whole insulation is the better option.
If your utility bills are higher than usual, it could be a sign that your crawl space needs insulation.
When crawl space insulation isn’t working at its best, your heating and cooling systems work overtime to help keep a stable indoor temperature. As a result, you get higher energy bills.
Inspect your crawl space regularly for signs of moisture problems. That includes mold, mildew, or dampness.
When the insulation gets wet, it attracts mold and mildew, which release mycotoxins that are dangerous for your health.
Even after the insulation dries, the spores remain in the air and can travel to other areas in your home.
If you had any recent leaks or plumbing issues, ensure to carefully inspect your insulation for signs of moisture or dampness.
If you detect moisture issues early, you can replace only the affected areas. However, in other cases, you might need to replace the whole insulation.
Insects and rodents are attracted to warm, damp places, so a moist crawl space is ideal for them. If you’re dealing with a pest problem, inadequate insulation might be the cause.
There are several types of insulation materials out there, each with its own set of benefits and drawbacks.
Fiberglass batts are a traditional material for insulating crawl spaces. That’s because they’re affordable and easy to use.
Even though many people still use fiberglass batts for insulation, they’re not the best option for crawl spaces, especially the ones with moisture issues.
If you want insulation that will do the job only for 3-5 years, then fiberglass batts might be an option. However, fiberglass loses effectiveness after a few years, as it’s heavily affected by moisture and mold.
Also known as foam board insulation, rigid foam is one of the best insulation materials for crawl spaces.
As the name suggests, the rigid foam provides maximum rigidity that you won’t get from open-cell foam insulations. As such, rigid foam is versatile and can fit walls, rim joists, and overhead floor joist cavities.
Further, rigid foam insulation is moisture resistant, so it’s ideal for crawl spaces prone to dampness and pest infestations. This helps protect your home from potential water and air damage issues.
Rigid foam also has a high R-value per inch, which means it provides superior thermal resistance. This can help make your home more energy efficient and reduce your energy costs.
Spray foam is another great option for insulating crawl spaces. Closed-cell spray foam is a highly effective air and moisture barrier, thanks to its ability to expand and fill in gaps and cracks,
This provides a continuous insulation layer for better air sealing, improving energy efficiency and air quality in your home.
Spray foam also has an excellent R-value, providing top-notch thermal resistance. Moreover, it’s moisture-resistant, making it a suitable insulation option for damp crawl spaces.
We can fairly compare closed-cell spray foam to rigid foam.
On one hand, rigid foam takes a lot of time and effort to install, and if it’s not installed by a professional, it might not work at its best. On the other hand, spray foam is much easier to install while providing almost everything rigid foam can offer.
What’s more, spray foam is more efficient in stopping air leaks. The only downside for spray foam might be the installation costs. However, it’s a great investment in your home’s health and energy efficiency.
Proper insulation is one of the best ways to keep moisture away, reduce grafts, and discourage pests. Let’s see how to insulate your crawl space.
Before you start, inspect your crawl space for any signs of water damage, pests, or mold. You should also determine whether your crawl space is ventilated or unventilated, as this will affect your methods and choices.
For vented crawl spaces, you need to opt for non-permeable materials. Use closed-cell spray foam as it provides effective thermal insulation and air sealing.
In unvented crawl spaces, it’s critical to insulate the walls. You can use rigid foam panels, spray foam, or a combination of both. Spray foam is better for insulating rim joists, while rigid foam panels are more effective for the interiors of the walls.
Note that if you decide to insulate your crawl space using rigid foam, you’ll need to hire a professional to ensure you have it installed correctly.
Before you start installing the insulation, you must seal any leaks or gaps in the rim joists, foundation walls, and vents. You do this with caulk or expanding foam.
Use silicone caulk for small cracks. And for larger gaps, use expanding foam.
Many homes include air vents between the crawl space and the outside to improve airflow. However, these vents only entrap moisture, which creates an ideal environment for mold and pests.
To prevent this, go outside your home and cover any vents and airways that lead to your crawl space. You can do this by inserting caulk into holes and cracks or using vent covers to block the vents.
Installing a vapor barrier is vital to prevent moisture from entering your crawl space.
Lay a heavy-duty polyethylene sheet on the crawl space floor, overlapping the seams by at least 12 inches.
Then, extend the sheet up the wall about 6 inches and secure it with waterproof tape.
When insulating walls, it’s best to opt for rigid foam board insulation. First, cut the panels to size them so that they fit snugly between floor joists and the crawl space walls.
Then, attach the panels to the walls using waterproof spray adhesive.
The rim joists, where the floor joists meet the foundation walls, are a common source of heat loss, so they should be insulated as well.
Cut pieces of rigid foam so they can fit in rim joists, then attach them with spray adhesive. After that, ensure you fill any gaps or cracks with spray foam.
The amount of insulation you need in a crawl space varies depending on where you live.
The U.S. Department of Energy recommends that homes in warm climate zones should have R-11 (3.5 inches thick) insulation on the floor. Meanwhile, homes in colder areas need R-25 (6 to 8 inches thick) insulation.
Check out this climate zone guide if you’re not sure how much insulation you need in your crawl space.
We hope the information shared in this article has helped you understand how to insulate a crawl space. This often-neglected space can have a significant impact on the comfort, energy efficiency, and overall health of your home.
That’s why insulating your crawl space is essential to maintain an optimal living environment and prevent moisture-related issues that could ruin your home and belongings.
I have a bachelor’s degree in Computer Information Systems and over 10 years of experience working in IT. As a homeowner, I love working on projects around the house, and as a father, I love investigating various ways to keep my family safe (whether or not this involves tech). I’ve also played guitar for almost 20 years and love writing music, although it’s hard to find the time these days.