Why You Should Be Using Spray Foam to Insulate Your Crawl Space

A crawl space can be found in some homes between the ground and the first floor. It is typically an unfinished area with a dirt floor. In some cases, it can be a very narrow space with as little as two feet, just enough room to crawl in, thus the name. Crawl spaces can be found in around 15% of homes, and it is a common point of access for electrical, plumbing, and ventilation systems. 

Crawl spaces are most commonly found in homes that can’t be built on other common types of foundation, such as a slab on grade or basement, due to soil conditions in the area.

Why Do Homes Have Crawl Spaces?

The crawl space provides a base of support for the above living areas and provides a buffer between the home and the ground. These spaces are often vented allowing air to circulate from the outside or to an adjoining basement. They are also often used to house pipes, ductwork, and electrical wiring that runs through the house. If your crawl space is large enough it can be used to house the heating and cooling units, such as a furnace or an air conditioner.

Some homeowners may also consider the crawl space as an extra place for storage, although the potential for moisture accumulation should be considered before storing any valuables. If your crawl space is unfinished, it might be a good place to store extra construction materials such as bricks, tile, pipes, or other materials that aren’t going to be damaged by moisture. 

Why is Crawl Space Insulation Important?

When your home is elevated off of the ground, insulation within your crawl space is used as a way to maintain your building envelope. You can reduce the severity of temperature fluctuations within your home by installing insulation within your crawl space. Having insulation properly installed in your crawl space will also help to reduce your monthly energy bill, as well as improve air quality

Fiberglass is No Good for Crawl Spaces

Once upon a time, people used to think that installing fiberglass batts in your crawl space was a good idea. However, over time, we have found this is generally a bad idea. It can easily fall out of place, producing waste and a big headache for homeowners. The fact is, it’s just not doing its job as an insulation material if it’s falling down on the ground.

Even worse, fiberglass that manages to stay in place can actually cause damage to the wooden flooring of your home. This is because fiberglass batts work much like a sponge, absorbing and holding water. The moisture then is easily wicked away into the joists, beams, subfloor, and other wooden components of your building. Eventually, the fiberglass batts will fall down because they are too heavy and full of water.

Damp Flooring Can Cause Major Problems

If your floorboards are constantly wet, you could be inviting some major issues. Termites, for example, are attracted to the soft wood because it’s easier for them to burrow through and make their nests. Fiberglass batts may also make an attractive home for larger pests like rodents who are looking for materials to make their nests. Worst of all, these wet surfaces can attract mold and mildew. These are all issues that you will definitely want to avoid.

The accumulation of water, mold, and mildew causes the wood in your framing to rot. Over time, as the wooden joists and beams of your structure begin to decay, you will find yourself with sagging floors. The only fix is to completely replace the damaged sections.

All of these issues can add up to a very costly repair bill. Eliminating mold found in your home can cost up to $4,200, while the average cost to repair floors that are sagging can be as much as $5,600. Between repairing sagging floors, getting rid of mold and pests, you could be looking at as much as $10,000 in repairs.

You can avoid these issues altogether by replacing your old fiberglass insulation with a high-performing spray foam product which is an excellent preventive measure.

How Do You Know Your Crawl Space Needs Insulation? 

Constantly dealing with cold floors inside your home is probably the biggest sign that you need extra insulation in your crawl space.  This is due to the cold air within your crawl space traveling up through your floor.

Not only can cold floors be the reason for your higher monthly utility bill, but you may also be vulnerable to freezing pipes. If you have ductwork running under your house, cold air in the crawl space could be sucking the heat away from your ducts before it ever has the chance to reach your living space, also contributing to higher energy bills and an increased workload on your heating system.

How Can You Benefit from Insulating Your Crawl Space With Spray Foam?


Homeowners will notice energy savings and efficiency soon after they insulate their crawl space. Many homeowners say that they quickly recover their investment after insulating their crawl space because they will not have to pay as much when their climate control systems are in use. 

Your insulation project eventually pays for itself in energy savings, as you don’t have to keep your furnace running for so long. It turns out that the cost of insulating your crawl space is actually minimal when compared to the reduced utility costs that you will enjoy over the lifetime of your investment. 

HVAC Longevity

When your heating and cooling system is forced to work harder as the result of insufficient insulation, it is bound to break down prematurely. When the insulation in your home’s crawl space is sufficient, it will prevent warm and cold air from escaping, therefore reducing the workload on your HVAC system and prolonging its lifespan. When your crawl space is properly insulated in conjunction with the rest of your home, you can reduce the infiltration of outside air, allowing your heating and cooling system to function better long term.

Air Quality

Many people are so worried about the pollution of the air outdoors, that they don’t give much thought to the quality of the air inside their home. Due to gas being released from indoor finishes and furnishings to a lack of proper ventilation, and common mold and mildew issues, it is often found that air quality is worse inside the home than it is outside.

When you have a good quality insulation system in place, it will be much easier to prevent the infiltration of allergens, pollutants, and other irritants. This is doubly important if you live in an area with poor outdoor air quality or lots of allergens. You will be able to keep the air inside of your home even cleaner when a high-functioning ventilation system when it is combined with proper insulation.

Temperature Control 

If you have a crawl space that is not properly insulated, you may be a victim of uncomfortable temperatures during the winter, and sweltering hot temperatures during summer. Air that is allowed to enter through the crawl space then moves up through the floor into the home. Having a good insulation system in place in your crawl space will help to keep your home at a consistent temperature all year.

After you’ve done the initial investment to update the old insulation down in your crawl space, you will immediately benefit from improved comfort throughout your home.

Moisture Control 

Spray foam insulation repels water, which helps to keep mold and mildew at bay. Here in North Idaho, your home may be particularly at risk of dangerous levels of moisture. If your home isn’t properly insulated and well sealed, it’s likely that mold or mildew may be hiding in your crawl space, and other dark areas of the house such as the attic.

Deters Pests

Spray foam insulation is a very dense material, which makes it difficult for pests like insects and rodents to penetrate. It also does not provide a suitable source of nesting materials for vermin.

No Need For Hardware

Spray foam can stick to any surface and expand to fill the space where it’s applied. This keeps it from falling down or deteriorating. You can expect your spray foam insulation to last the lifetime of your home.

What is the Cost of Insulating Your Crawl Space? 

Not every crawl space is created equally, therefore the cost of insulating your crawl space with spray foam can vary. However, we estimate the average cost of using spray foam to insulate your crawl space is somewhere in the neighborhood of $2-3,000.

What Determines the Cost of Crawl Space Insulation? 

The size of your individual project is going to be the biggest variable when it comes to determining the cost of insulating your crawl space. It also depends on the scope of your project. For example, if you are wanting to insulate the underside of the floor in your house as well as the walls of your crawl space, those are two very different projects. There’s a big difference in the area when it comes to insulating the underside of the floor versus the crawl space walls.

The varying height of walls in your crawl space will play into the cost calculation. Usually, the walls within crawl spaces are between one and three feet high, but they may also be much taller. The higher the walls, the higher the cost of the installation.

If you are looking to install a vapor barrier as well, this will be an additional charge.

Further complicating things, your choice of materials will also come into play. Closed-cell spray foam tends to be more expensive than open-cell, so whichever variety you choose will help to determine the price.

While there are several differences between open and closed cell spray foam, such as the composition, sound dampening abilities, the permeability to moisture, and the blowing agent used, both types are going to create a solid barrier against the flow of air which will insulate your crawl space.

Lastly, you may have to factor in the cost of removing your old insulation when determining the total cost. You will need to get rid of any existing insulation in the crawl space before you can begin with the installation of spray foam. While removing the old insulation may come with an extra cost, it can save you from the headache of tearing it out yourself and finding a place where it can be properly disposed of.

What to Expect When Installing Spray Foam in Your Crawl Space 

Before beginning the installation of your new spray foam system under your home, contractors will have to come and remove any insulation that might already exist in your crawl space. Old installations must be removed in order for the new spray foam to achieve a good airtight seal.

If you are insulating the walls of the crawl space, the next step will be to put a vapor barrier down on the floor. The vapor barrier is a piece of heavy-duty plastic that covers the floor and will be rolled up the walls a short distance. The foam is then sprayed onto the wall overlapping onto the vapor barrier in order to create a seal against moisture. This process is referred to as encapsulation.

If you only desire to insulate the underside of the floor, then it will not be necessary to put down a vapor barrier.

After the foam has been sprayed and allowed to set, the contractor will do what’s necessary to clean up the area and make it look nice again. 

What Services Should Be Included by Your Crawl Space Insulation Contractor? 

A good insulation contractor should be ready to complete the job from the very beginning all the way to the very finish, starting with an estimate and leaving you with a more comfortable living space. You should go with a contractor that includes some of the following services:

  • A free estimate for the full cost of the project
  • A liaison who stays with you throughout the duration of the projects to answer any questions
  • Help with securing financing
  • Crew to remove and properly dispose with any old existing insulation
  • Crew to clean up after the completion of the project, leaving your home looking like new.
  • Help with applying for any rebates or tax credits that may exist in your locality
  • Warranty for the work done

Are You Prepared to Insulate Your Crawl Space?

If you are ready to insulate your crawl space with spray foam, you want to make sure that you find a reputable contractor to do the work underneath your home. If you live in Spokane or North Idaho be sure to call Evergreen insulation. Our team is standing by to schedule an appointment for your free estimate.