How to Insulate a Crawl Space

When homes are built, the type of foundation can make a big difference. While many homes are built with a basement or on concrete slabs, crawl spaces are common for homes built on a slope, or where there’s a risk of flooding. Crawl spaces are increasingly common on new constructions throughout the US. In fact, nearly 20% of new homes are built using a crawl space. 

Your home’s crawl space creates a barrier between the ground and the floor of your home and can prevent flood water from entering your living space and reduce the risk of termite infestation. It also provides easy access to your plumbing, gas connections, wiring, and ventilation so service technicians can make repairs without digging.  

However, one drawback of the crawl space is the possibility to let hot or cold air in and out of your home, which can lead to excess energy use and uneven temperatures throughout your home. It can also allow moisture buildup to create mold and mildew and lead to rot in your support beams, and in many cases the moisture buildup can penetrate your floor, causing mold and mildew on carpets and rugs. Luckily, these issues can be controlled through ventilation, air sealing, and most importantly, proper insulation. 

If you have cold floors in the winter, or you’re dealing with high energy bills each month, it’s time to consider adding insulation to your crawl space. So how do you approach this project, and is it worth the time and investment?

Benefits of crawl space insulation

Proper insulation in your crawl space, combined with air sealing and insulation throughout your home, can help keep your house more comfortable throughout the year by preventing hot or cold air from entering and exiting your home. It can also help you avoid moisture buildup that can compromise the structural integrity of your home and bring mold and mildew problems along with it. 

When your home is well insulated, you can go longer in the fall and spring without turning on your heater or air conditioner, and help your HVAC system work more efficiently when it is time to turn it on for the season. This can reduce wear and tear on your heating and cooling equipment, and in turn save you money on your monthly bills and maintenance costs for your system. 

A well sealed, insulated, and ventilated home also can help improve your indoor air quality by keeping allergens and other contaminants out of your home. Additionally, by making your home airtight you can reduce entry points for rodents and other pests, which can save you money on exterminators and repairs, as well as help you avoid diseases brought into your home by infestations. Insulation in the crawlspace can also protect your pipes from freezing in the winter, which can save you thousands of dollars on plumbing repairs. 

The pitfalls of DIY

While you can insulate your crawl space on your own, there are plenty of safety concerns to consider. Handling damaged insulation can irritate your skin, eyes, and lungs. You may also expose yourself to mold or bacteria left by pests. Additionally, the type of insulation material you use and the spaces you install it depends on a lot of factors, including the type of existing insulation that’s in place and whether or not you have a ventilated crawl space.

If you see evidence of water damage, broken insulation, or rodent infestation, the safest thing to do is hire a professional. They have the safety equipment and experience to clean out your crawl space and install adequate insulation. An expert can also help you rodent-proof the space to prevent infestations and help you decontaminate areas where rodents have made nests.  

A professional can help you determine the best materials for the job, including the proper R-value you need to use, and ensure your insulation is safe from moisture damage. If you’re not sure about the benefits of using rigid foam vs fiberglass batt insulation, you should consult an expert before you wind up wasting money on the wrong materials. 

Any time you perform work on your home without hiring a professional, you run the risk of missing out on benefits from your home warranty or insurance policy if you ever need to file a claim. Improper air sealing or insulation installation can have a negative impact on your home’s ventilation, increasing your home’s risk for water damage. It can also create a fire hazard if insulation is installed too close to electrical wiring. 

In the long run, hiring a professional can help you keep your free time open and ensure the job is done properly without wasting any materials or accidentally injuring yourself, especially when you are working in tight spaces like the crawl space. Contractors also will have comprehensive insurance coverage that will take care of accidental damage. 

So what does the job entail, exactly? There are two common approaches, depending on what type of crawl space you have. 

Insulating a vented crawl space

If you have a vented crawl space, you can simply install rolled fiberglass directly on the subfloor and between the floor joists. The insulation should be fully secured with a mechanical fastener, and you should be sure to seal off all the seams. Once the insulation is installed, you should add a vapor barrier over the insulation to protect it from water damage. 

Before you install underfloor insulation, it’s crucial to identify any air leaks and seal them using caulk or another appropriate sealant, depending on the size of the cracks. Air leaks are commonly found anywhere pipes or wires penetrate the floor. You can use weather stripping on hatches that provide access to the crawlspace within the house to prevent air leaks. 

Some homes use the crawlspace for air ducts to deliver conditioned air throughout the house. You should be very careful not to damage the air ducts, and consider adding insulation to them as well if they don’t have any. 

Ventilated crawl spaces were the standard for many years, but newer homes are more likely to close off the area under the home. While vented crawl spaces offer certain advantages, especially in areas prone to flooding, it’s worth consulting a professional and considering whether you should seal your crawl space vents and convert to an unvented, or encapsulated, crawl space. 

Insulating an unvented crawl space 

An unventilated crawl space should be treated as part of the conditioned space, and you should insulate the walls rather than the subfloor. In many cases, this will require less insulation. 

You should check all the exterior walls for air leaks and seal them off using caulk or foam sealant as you work.

With an unventilated crawl space, you should also consider adding a termite barrier that covers the areas between the joists and across the foundation wall. You should also add a moisture barrier to the dirt or concrete floor beneath your crawlspace to prevent condensation from creating water problems.

Unvented crawl spaces can offer any advantages for home homeowners, but they aren’t always the best option for your home. Unvented crawl spaces can reduce your risk of termites and other pests, and they are often better at controlling humidity and excessive moisture buildup. They can also prevent outdoor air, and all the allergens and other contaminants that come along with them, from entering your home, and can help keep your floors warmer in the winter. 

How Attic Construction can help

Fiberglass insulation can last for decades with proper protection, but it can become damaged and lose its thermal protection from things like moisture buildup, mice or rats chewing through it, and dirt or other debris. Our team can protect your insulation by installing a vapor barrier, ensuring your crawl space vents are functioning properly, and protect your space from rodents. 

On its own, crawl space insulation will only address some of your heat loss. Without adequate attic and wall insulation, you will still waste a lot of energy keeping your home comfortable. Our team of insulation professionals can insulate your crawl space as well as provide air sealing and insulation throughout your home so you can get the full benefits from your investment.  

Attic Construction is the top rated crawl space clean up and attic insulation company in San Diego, Orange County, and the Phoenix, AZ, area. Our offices are open 7 days a week to provide insulation services and rodent proofing for homeowners looking to save money on their energy bills and maintain a safe, comfortable space throughout the year. Set up your free inspection, and we perform detailed evaluation of your space with pictures, and we will provide an estimate before we leave. We are confident in our craftsmanship, which is why we offer an unconditional 1-year warranty on all work we perform. Contact us today to schedule your consultation and learn more about how we can help. 



Leave a Comment

Your email address will not be published. Required fields are marked *