Home Retrofit Calculations Guide Part 2: Basement Insulation

What Are The Risks of a Poorly Insulated Basement?

When your basement is under-insulated, heat transfer will occur eagerly throughout the walls and foundation of your basement. This lack of insulation will cause your HVAC system to be overworked to maintain a stable and comfortable interior temperature.

Does Insulating Your Basement Help?

Proper basement insulation will effectively prevent the transfer of heat between basement walls and foundations and the outdoors. This insulation capacity means that your basement will not be at the whim of frigid winter temperatures or the hot and humid summers. When your basement temperatures are stabilized with high-performance insulation and a sealed building envelope, your entire home will also benefit from steadier, constant interior temperatures.

Quality basement insulation will help reduce the "cold floor" effect throughout the house. It can also help stop the "stack effect" in your home. This effect occurs when warm air rises into your ceiling or attic, and cold air enters to replace it (usually through the basement).

How Much Will Basement Insulation Cost?

The answer will depend entirely on several variables, including:

• The type of insulation you choose
• The size/square footage of your basement
• Whether you are planning on insulating just your basement walls or your foundation as well
• The climate you live in, as colder climates will require more robust insulation

However, improving the insulation in your basement can be surprisingly affordable, with the total price for labor and materials per square foot costing between $2.80 to $4.50. For 500 square feet, this correlates to between $1,500 and $2,200 for batt insulation, with northern locations and more expensive products costing more.

How Much Is Your Current Basement Insulation Costing You? 

Spending around $2,000 to improve your basement insulation might seem like a steep cost for homeowners in a tight financial situation. However, consider the following: About 90 percent of homes in the United States are under-insulated. This lack of insulation leads to houses wasting at least 20 percent of the heat they generate to stay warm during the winter. The American Gas Association estimates that the average American household spends around $661 per year on natural gas for heating their home. For all-electric homes, you will most likely be paying even more for home heating costs every year.

Suppose 20 percent of the heat generated by your central furnace, baseboard heaters, heat pump, or other heating device is lost due to insufficient insulation. In that case, you might be essentially wasting around $130 per year. Homes located in colder regions will most likely see even more economic losses due to the increased heating demand.

How Much Would You Save Annually With Additional Basement Insulation? 

Based on the figures above ($661 average heating cost for natural gas-powered homes and an average of 20 percent wasted heat), improving your basement insulation could save you at least $130 per year. If you want to maximize your savings, consider also insulating other parts of your home, like walls and attics. Even if you just start with the basement, it is worth noting that basements are often the most under-insulated part of the home. SO, this job can get you started on your way to a super-efficient home.

A more ambitious insulation retrofit that improves the insulation in your attic, crawl spaces, and basement could save you 15 percent on your heating and cooling costs (EPA estimates). For many homeowners, that adds up to a savings of more than $200 per year.

What is the Payback Period for Improved Basement Insulation?

Let's do the math. A 700 square foot basement with an insulation overhaul at an average cost of $3.00 per square foot would cost $2,100 for materials and labor. Suppose you are paying an average of $700 per year for home heating and are losing about 20 percent of that heat due to lousy basement insulation. In that case, you are losing $140 each year in wasted energy costs. Given these two figures, your estimated payback period for a basement insulation retrofit is about fifteen years. This estimate is probably lower, in actuality, given the reduced AC costs that you can achieve. Improved basement insulation will also lower the demand for cooling during the summertime. A 10-15 year payback period for improved basement insulation isn't bad, especially given that properly-cared-for insulation can last between 20 years for fiberglass batts to over 100 years for closed-cell polyurethane spray foam.

What Are the Other Benefits of Upgrading Basement Insulation? 

The benefits of this home retrofit go beyond economic considerations. A well-insulated basement will reduce the carbon footprint of your home by lowering your heating and cooling load. A well-insulated basement can also limit excess humidity in your home, thus improving indoor air quality. Mold spores are one of the most common indoor allergens and pollutants, and moist or damp basements are primary places for mold spores to grow in a home. An insulated basement will add comfortable living space to your home. Instead of merely using your basement as a makeshift storage room, high-performance insulation can allow you to turn your basement into a beautiful and practical space for bedrooms, living rooms, playrooms, and more.

What Are the Differences in Cost and R-Value Various Insulation Options?

So how do you know what type of basement insulation is right for your home? If your basement is not properly sealed and moisture or vapor issues might become a problem, you should most certainly opt for closed-cell polyurethane spray foam. This option is more expensive than other insulation types such as fiberglass or cellulose. However, spray foam can be applied directly to the concrete walls, offering both a thermal and moisture barrier for your basement. The cost of adding a high-performance moisture barrier and framing your walls would most likely offset any savings related to opting for cheaper fiberglass insulation.

Suppose your existing basement already has a high-performance moisture barrier and is already framed or studded. Then you can opt for any type of insulation. Check out this Rise guide for the best types of insulation.

What Are the Environmental Considerations Related to Basement Insulation Options?

Unfortunately, many spray foam insulation products on the market today use blowing agents. These blowing agents are necessary to create the tiny bubbles that give foam its insulating capability. Many of these cause an enormous amount of damage to the environment. These blowing agents release hydrofluorocarbons (HFCs), which have a global warming potential that can be 3,000 times higher than carbon dioxide.

When sourcing the most environmentally friendly spray foam insulation products, make sure to look for products that advertise the use of HFOs instead of HFCs as primary blowing agents. Rise has detailed many of these great options in our In-Depth Guide to Spray Foam Insulation.