Which is the Best Insulation to Prevent Mold?

The growth of mold is a menace that affects most homeowners. Mold grows due to unregulated temperatures and moisture in a building. We all know the dangers of living in a moldy house-from the musty odors, respiratory problems, to damage of property.

Proper insulation is your best bet at combating mold infestation in your home or building. There are many types of insulation, such as spray foam, mineral wool, and cellulose. But, which insulation is the best to deal with mold?

Spray foam carries the trophy of the best insulation for mold prevention because it has air seals, and it doesn’t retain any moisture. Some other types of insulation can aggravate the mold situation, especially if they hold in moisture.

Now, let’s dig deeper so that you learn how spray foam insulation prevents mold.

Types of Spray Foam Insulation

There are two types of spray foam. We’ll discuss each, including its benefits here.

1.       Closed cell spray foam

Albeit being pricier, closed cell spray foam forms the best air seal when set in place. Due to its thick density, the insulation also prevents moisture and mold buildup on surfaces. Compared to the open cell, a closed cell has a greater R-Value that makes it better at regulating the heat from in and out of a building.

2.       Open cell spray foam

Open cell spray foam is cheaper than the closed cell. Open cell is less dense but works great at noise insulation. Once you apply open cell insulation, it rises fast, filling all the crevices, making structures more rigid. Open cell insulation traps air in between cells, making it appear spongier and ultimately not good at creating a moisture barrier.

What is Spray Foam made of?

Spray foam is a combination of isocyanate and polyol, often referred to as component A and B. Component B (polyol) of spray foam insulation is often a catalyst or blowing agent. When the A and B side of the chemicals combine, a chemical reaction occurs, forming foam insulation on surfaces.

How is Spray Foam Installed?

Have you recently decided to insulate your home using spray foam but don’t know how to do it? Here is a step by step guide to get you going.

a)      Wear protective gear such as goggles, gloves, shoes, and clothing because fumes emitted are dangerous.

b)      Set up everything such as ladders so that once you start spraying, nothing gets on your way.

c)       Use plastic to cover all the windows and doors. Also, make sure to cover all electric switches and outlets using tape.

d)      Lubricate the edge of your gun before installing a tip and remember to lube every time you change the tip and also after use.

e)      Connect the gun to your hose.

f)       Shake the cans containing the spray before use.

g)      To prevent bulging on the sheathing, start with the frame before spraying the wall cavities.

h)      Allow each lift to cure before adding another layer. Each lift should not be more than 2 inches thick.

i)        Once done, scrape off any excess foam so that the surfaces will have a uniform thickness.

What is an Air Seal?

Air seals occur naturally in buildings during construction. Such air leaks are common around openings such as vents, doors, and windows. Air leaks allow indoor air to escape to the outside while outdoor air finds its way to the inside.

You would need to use more energy on air conditioning to maintain quality indoor air. Alternatively, you would have to deal with poor air quality inside your home. Air sealing is the only permanent solution to air leaks, and spray foam insulation can be that solution.

Spray foam insulation upon application expands, filling any cracks, crevices, or air spaces on the surfaces of your home. You, therefore, kill two birds in one stone-literally! You get your home perfectly insulated, and you also air seal your home, thus improving the quality of air in the building.

Why does Spray Foam Insulation not Retain Moisture?

Several aspects make spray foam insulation perfect at keeping building moisture at bay. By forming insulation, spray foam regulates temperatures inside a building. High temperatures lead to condensation on surfaces. The condensation later creates moisture problems that lead to moldy surfaces.

Spray foam also forms an air seal, thereby regulating the flow of air in and out of a structure. It, therefore, means that wet air from the outside cannot penetrate to the inside. Wet air can make surfaces wet, which then attracts mold.

Why are Fiberglass and Mineral Wool not good for Preventing Mold?

Mold spores exist in the air and only need the right temperatures, moisture, and food source to thrive. Insulation is the best shot at keeping moisture away from a building. However, with the wrong choice of insulation, the situation can get from worse to worst.

For example, fiberglass isn’t a great insulation for preventing mold. Fiberglass is made of different organic materials and fiber. If well installed, fiberglass doesn’t attract mold. However, if installed in wet areas such as a crawlspace or the basement areas, the materials may retain moisture, which leads to the growth of mold. The fibrous materials of this insulation also trap dust and mold spores from outside.

Mineral wool, on the other hand, doesn’t form air barriers, no matter how well you install it. It, therefore, means that wet air from outside could get inside your house, leading to condensation problems. Condensation takes place when hot air from outside meets cold air from inside. Guess what this means? Your guess is as good as mine- mold infestation!


Mold is a real problem in most buildings all over the world. Moisture accumulation on buildings leads to damages worth millions of dollars. Insulation can prevent moisture accumulation in buildings only if you choose the right insulation method. Spray foam insulation forms the perfect insulation, noise barrier, and has air sealing properties that prevent mold.

Did you find this guide helpful? Please share with us your experiences preventing mold in your home.