Crawl Space Heater: What You Need To Know

Introduction – Heating Unusual Spaces

[Update 03/16/2024: we incorporated a recent news article about a fire caused by improper heating of a crawl space to underscore the seriousness of this topic]

We talk a lot about heating and cooling the house. What about heating the space beneath the house? That space is called the “crawl space“. As the name suggests, a crawl space heater is used to heat the space under your house where there are no windows. Think of the crawl space as a very primitive basement – the same things to care for the basement apply to a crawl space if you want to add heat to it.

Crawl space is the space beneath the ground floor of a house that doesn’t have a basement – in this diagram its the space holding the pipes

Crawl space heaters can be a great solution for homes with cold crawl spaces, as they provide a way to heat this often neglected area. Crawl space heaters are typically installed along the floor joists, providing warm air to flow through the crawl space and preventing frozen pipes or mold growth issues. While some models require a dedicated thermostat, others can easily integrate into your existing HVAC system for more control and convenience.

What Is A Crawl Space?

Not all homes have crawl spaces. In colder parts of the world, during the winter, water along with soil expands which pushes up everything on top. This phenomenon is called heaving. The frostline is the depth to which the ground freezes and heaves in winter. Building codes in cold climates require basements to be built below the frostline to prevent the foundation from heaving out of the ground as the frozen ground expands. In warmer parts of the world, a house can be built without a basement because the frostline is not as deep. These houses will have a crawl space beneath the 1st floor of the house rather than a basement.

Why Do You Need A Crawl Space Heater?

While you may not think about it often, the crawl space under your house is important in keeping your living spaces comfortable. Without a properly heated crawl space, you could experience issues such as frozen pipes, mold growth, moisture that and even weak foundation support. A crawl space heater can help ensure that these problems don’t occur.

crawl space heater
Pipes are frequently found in the crawl space

By providing consistent heating to the area underneath your home, a crawl space heater can prevent frozen pipes and moisture buildup, improve air quality in your living areas, and protect the structural integrity of your foundation. Additionally, investing in a crawl space heater can save you money in the long run by preventing damage caused by cold temperatures or excess moisture. So if you want to keep your home cozy and protected, don’t neglect the importance of a properly heated crawl space.

How To Prepare The Crawl Space For Heater Installation

If you are getting your crawl space heater installed by a professional company, they will usually take care of preparing the crawl space for you. However, if you are doing it yourself, there are a few things you will need to do to make sure the installation goes smoothly.

  • Cleaning – Make sure the crawl space is clean and free of any debris.
  • Water insulation – Make sure the ground and walls are insulated against water because the soil beneath the house is a big repository of moisture which evaporates and enters your house.
  • Heat insulation – Add new or replace old insulation on the walls and insulated ground so that the heat is efficiently trapped.
  • Drainage – Update the gutters, and make sure the ground outside the house slopes away so that water drains away from the crawl space.
  • Level – Make sure the crawl space is level. If it is not, the heater may not work properly.
  • Ventilation – Ensure ventilation that will let the moisture circulate out.

There Are Two Types Of Crawl Space Heaters

There are two types of crawl space heaters – electric and gas-powered. The main function of these heaters is to provide extra warmth in these otherwise cold areas of your home. One common type is an electric baseboard heater, which runs along the crawl space floor and emits warmth through convection. These heaters are low maintenance and easy to install but may not be energy efficient.

Electric crawl space heater

One of the main advantages of an electric crawl space heater is that it does not require venting outside, making it ideal for use in homes with limited or no access to ducts. Many models also come with built-in thermostats and timers, allowing you to customize your heating schedule depending on your needs.

Another benefit of using an electric unit is that no harmful emissions are released into the air, which can concern gas-powered heaters. In addition, these units typically have lower running costs than their gas counterparts, making them a more cost-effective choice overall.

Gas crawl space heater

Gas-powered crawl space heater provides an efficient heating solution for hard-to-heat spaces, but it also offers unique benefits like energy savings and improved indoor air quality. With a gas-powered crawl space heater, you can save up to 30% on your energy bills by reducing the strain on your HVAC system and preventing heat loss through the crawlspace. And because these heaters feature sealed combustion chambers and vents directly outside, they can improve the overall air quality in your home by reducing pollutants and allergens.

Another option is a forced air furnace, which allows for temperature control with a thermostat and can also act as the central heating system for the entire house. However, these require a more complex installation process and regular maintenance. Finally, hydronic or radiant-based heating systems use hot water pipes to heat the crawl space floor.

These can be highly energy efficient but may require professional installation and regular maintenance.

How To Cut Heating Costs For Your Crawl Space?

Keeping a crawl space warm can significantly add to your heating bill, but there are ways to reduce those costs. First, consider insulating the crawl space floor with fiberglass or spray foam insulation. This will help trap heat in the crawl space and prevent it from leaking through cracks in the floor.

Secondly, seal off any air leaks or gaps around vents or doors leading into the crawl space for added efficiency. Finally, consider installing a crawl space heater that is a more energy-efficient model, such as a radiant floor heating system or an electric heat pump.

By taking these steps, you can effectively reduce your heating costs for your crawl space without sacrificing warmth and comfort. Note: If you want to include lists instead of writing in paragraph form, you could use bullet points for each of the above tips, followed by a conclusion sentence summarizing the overall idea of cost-saving measures for heating a crawl space.

Reasons Not To Install A Crawl Space Heater

There are several potential reasons why you might not want to install a crawl space heater.

Energy Efficiency: Crawl space heaters can consume a significant amount of energy, leading to higher utility bills. If the crawl space isn’t properly insulated, much of this heat can be lost to the outside, making the heater even less efficient.

Fire Risk: Like any device that produces heat, there is a potential fire risk associated with crawl space heaters, particularly if the crawl space is filled with flammable materials such as insulation, wood, or stored items. The risk increases if the heater is not properly maintained or installed.

Increased Humidity: Crawl space heaters can contribute to increased humidity levels in the crawl space. This can lead to a variety of problems, including mold and mildew growth and damage to wooden structures.

Cost: The cost of purchasing, installing, and running a crawl space heater can be significant. It may be more cost-effective to insulate the crawl space and use other methods to prevent freezing or dampness.

Alternative solutions: Depending on the issues you’re facing with your crawl space, other solutions may be more effective. For example, if the problem is high humidity, a dehumidifier or proper ventilation might be a better solution. As we noted above, if the problem is cold pipes, insulating the pipes may be more effective.

Things To Consider Before Buying A Crawl Space Heater

When considering purchasing a crawl space heater, there are a few things to remember. First, assess the size and layout of your crawl space. A larger space may require a more powerful heater, while you can easily heat a smaller area with a smaller unit. It is also important to consider the intended use of the crawl space.

Consult with an expert to assess and size heating requirements

Will it primarily be used for storage or as living space? This will determine whether you need continuous heating or just spot heating in certain areas. In addition, think about the insulation and ventilation of your crawl space. Good insulation and airflow can greatly improve the efficiency of any heating unit.

Finally, consult an expert on what type and size of heater would best suit your needs and ensure to properly install and maintain it for optimal performance and safety. Considering these factors will ensure that you make the right decision when choosing a heater for your crawl space.

Alternatives To Crawl Space Heaters

Solutions for preventing frozen pipes

If preventing frozen pipes is a concern, there are a few additional strategies that can be used, often in combination with encapsulation:

Pipe Insulation: This is one of the most direct methods of preventing pipes from freezing. Special insulation can be fitted around pipes to reduce the rate of heat loss, making them less likely to freeze.

Heat Tape: Also known as heat cable, this is a product that can be wrapped around pipes and then plugged in to provide heat directly to the pipes. There are different types of heat tapes designed for different applications, so it’s important to select the right product and install it correctly.

Solutions for preventing mold in the crawl space

Crawl space encapsulation and dehumidifiers are methods used to control the climate in a crawl space and, in turn, improve the comfort, energy efficiency, and air quality of the whole house.

Crawl Space Encapsulation: This is a method used to seal the crawl space from outside elements. This process includes installing a vapor barrier, which is a thick, durable plastic sheet, along the floor and walls of the crawl space. Seams are typically sealed with special tape to ensure a complete seal. The vapor barrier prevents moisture from the ground from evaporating into the crawl space, which can lead to high humidity levels, mold growth, and wood rot.

Dehumidifiers: Once a crawl space has been encapsulated, a dehumidifier may be installed to control the humidity levels. Even with a vapor barrier, some moisture may still make its way into the crawl space, whether through small leaks in the barrier or from the air in the house above. The dehumidifier works to remove this excess moisture, helping to prevent issues like mold growth and musty odors. Some dehumidifiers are specifically designed for crawl spaces and can be set to maintain a specific humidity level, often recommended to be below 50%.


A recent event in Mexico, Missouri, has a home suffering significant damage due to a fire caused by a propane heater used to thaw pipes in a crawl space. Given this news, the importance of safety in crawl space heating has never been more apparent. This incident, reported in January 2024, underscores the critical need for caution and proper use of heating equipment in such sensitive areas of our homes.

As experts in eco-living and sustainability, our goal at ShrinkThatFootprint is not only to recommend energy-efficient products but also to emphasize their safe usage. Here’s how this incident impacts our discussion on crawl space heaters:

  • Prioritize Safety Over Convenience: The risk of fire from improper heater use cannot be overstated. Always ensure that any heating device is used in accordance with manufacturer guidelines and never leave heaters unattended.
  • Educate on Proper Usage: Whether using propane or electric heaters, understanding and adhering to safe operating procedures is essential. This includes avoiding the use of extension cords with electric heaters, as they can overload circuits and increase fire risks.
  • Consider Safer Alternatives: Instead of relying on direct heat sources, explore safer alternatives for thawing pipes and heating crawl spaces, such as pipe insulation or professional services that specialize in safely managing these issues.


In conclusion, there are many factors to consider when trying to cut your heating costs for your crawl space. You can effectively keep your crawl space warm without breaking the bank by insulating the floor, sealing air leaks and cracks, and choosing an energy-efficient heater. Additionally, by taking other steps, such as ensuring proper insulation and ventilation in the crawl space, you can help maintain a comfortable home environment while reducing heating costs.​

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