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Spray Foam Insulation vs Fiberglass

Spray Foam and Blown-in Fiberglass are both solutions that will help your space become more energy-efficient and improve your home's value. At Midwest Roofing and Construction, we want to help you find the right insulation solution for your project and your budget. Learn more about the insulators we offer below and find out how you can start saving money on your energy bills! Spray foam insulation vs fiberglass - which is best?


What is R-Value?   

When looking into different types of insulators you will need to understand what R-Value means. The R-value is used in the building industry to measure the resistance of heat transfer between two surfaces and is paired with a unit of measurement. Insulators are typically measured by the inch with higher R-Values indicating a more effective insulator. Residential codes require homes to meet certain R-values in different parts of the building and differ depending on your region of the country.


In Wisconsin, Illinois, and Iowa the highest required R-value is in the attic, where you are expected to achieve between R49 and R60 to meet building code requirements. For more information on R-value requirements, you can visit the U.S. Department of Energy’s website HERE 

What is R-Value?

R-value of Spray Foam vs. Blown-in Fiberglass

There is a clear difference when comparing the R-value of spray foam to the R-value of traditional blown-in fiberglass insulation. Closed-Cell spray foam has an R-value of 7 per inch - meaning if you have 7 inches of foam you will achieve an R-value of 49. Compared to blown-in fiberglass insulation which has an R-Value of 2.5 per inch and would require almost 20 inches to match the insulating value of Spray Foam.


It is also important to know that fiberglass insulation loses R-value over time as it compresses and decreases in efficiency as temperatures drop. Spray foam allows you to properly insulate in far less space than any other insulation available making it perfect for lofted and cathedral ceilings that do not have the space to spare. 

R-Value of Spray Foam vs. Blown-in Fiberglass

Installation of Spray Foam and Fiberglass 

It is important to have your insulation installed by a professional who can ensure you are getting the best seel and the most out of your new insulation. Both Spray Foam and Blown-in Fiberglass have their advantages and disadvantages when it comes to the installation process. This is one of the most important things to understand when choosing which is best for you.  

The higher R-Value of spray foam makes it an attractive option for many looking to increase the efficiency of their building. However, due to the application process, it can only be added to exposed walls which generally limits its use to new builds, additions or complete remodels. Spray foam is an amazing adhesive and can be applied directly to almost any surface including steel walls making it perfect for those who are looking to heat a shop, shed, or garage. The installation process can be very messy and will release harmful gases that need to be aired out before the area can be available again. It is also important to note that spray foam can only be installed when surface temperatures are at least 60 degrees or higher. Making it difficult to install in the winter when temperatures are low.  

Blown-in insulation can be installed at any time, at any temperature. The only thing you will need to add an extra layer of protection to your home is an access point. This is typically not a problem for attics but can be an issue if you are looking to add insulation to your walls. Installation is quick and easy and creates a minimal mess with almost zero waste. Blown-in fiberglass fills in spaces and gaps far better than traditional fiberglass batts with less effort. It can also be added on top of your existing insulation for increased efficiency. We do not recommend adding fiberglass to existing cellulose insulation as it will decrease the performance of both. 

When possible a combination of spray-foam and blown-in fiberglass can be one of the most effective ways to insulate your home. The advantages of spray-foam described above and below combined with the affordable coverage of blown-in fiberglass will help you achieve a high R-value within a budget. At Midwest Roofing and Construction, you will be able to work with an expert who can help you achieve your insulation goals. 

Installation of Spray Foam vs. Blown-in Fiberglass

Air and Moisture Protection 

Spray foam creates an airtight seal filling in almost all cracks as it expands. This seal makes it harder for heat to escape and prevents air and moisture from reaching your structure's framing, preventing rot and mold from forming in the long run. The added protection spray foam gives your building will increase its value and longevity.  

Blown fiberglass insulation does not create an airtight seal and allows air and moisture to flow through it that will eventually lead to degradation over time.   Blown-in fiberglass easily fits closely around pipes and in hard-to-reach places in a way rolls of batt insulation cannot.  

Air and Moisture Protection

Longevity of Insulation

When properly installed, spray foam can last indefinitely while fiberglass insulation will require some upkeep. Spray foam can withstand weathering without losing any efficiency. The waterproof, airtight seal spray foam provides allows it to hold strong against almost any natural force it faces. This not only adds an extra layer of protection but will increase the strength of your structure.  

If you are looking to add fiberglass insulation you will need to ensure your space is properly sealed or you will risk ruining the insulation. Exposing fiberglass insulation to moisture and airflow from leaks will decrease its lifespan significantly. Over time blown-in fiberglass tends to compress and degrade losing some of its R-value, especially if it has been walked on.  

Cost of Fiberglass vs. Spray Foam Insulation 

There is a significant difference in price when it comes to Fiberglass vs Spray Foam Insulation. Spray foam will generally cost two to three times more than blown-in fiberglass due to the material, time, and expertise required for proper installation.  

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Which Type of Insulation is Right for Me? 

In Wisconsin, Illinois, and Iowa proper insulation is a must.  You will never regret adding an extra layer of insulation during the harsh winters and hot summer days. If your project allows for spray foam installation, Midwest Roofing and Construction highly recommends that you take advantage of the long-term savings and increased value this material gives your property.  When spray foam isn't possible, blown-in fiberglass is a suitable answer for your energy saving needs. The value and ease of installation make it one of the most popular insulators in our region for a reason. In some cases, a combination of spray foam and blown-in insulation will give you the results you need for a price you can afford. What is right for you depends on the conditions of your project. If you need help deciding give us a call and one of our experts will help you find the right insulation solution for your home or business!  

Longevity of Insulation
Cost of Spray Foam vs. Blown-in Fiberglass
Which Type of Insulation is Right for me?

For more information about our insulation services, or to schedule your personalized estimate with us, please call Midwest Roofing & Construction LLC at 800-551-8251.

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