Crawl Space Insulation - The Good and the Bad

Tuesday, January 21st, 2020 by Amanda Waldmann

Crawl Space Insulation - The Good and the Bad - Image 1


Last week, we talked about the damage an unencapsulated crawl space can do to your home in the cold weather. Today, let’s go over the types of insulation you might find down there, and what works best to protect your home.


The Bad


Fiberglass Insulation


This is the insulation you’re used to seeing throughout your home - the pink fluffy stuff that makes your hands itch if you touch it. It’s the industry standard in home construction, but it doesn’t belong anywhere near a crawl space (or basement, for that matter). See, fiberglass insulation has a paper backing, and when it’s in a damp environment it becomes the perfect harbor for mold. Mold only needs organic material (the paper backing) and moisture (an unencapsulated crawl space) in order to grow and thrive.


There’s also the fact that fiberglass insulation is absorbent; even a crawl space without standing water likely has humidity issues, and the insulation will absorb that water in the air until it gets so waterlogged and heavy that it just falls down completely. This leaves the crawl space totally unprotected.


Plastic Sheeting


If you search for DIY crawl space insulation tips, you’re likely to see the fiberglass insulation above, and also “plastic sheeting” that you simply roll out to cover the ground. The idea is that the plastic protects the crawl space from cold air coming up through the ground. But there are a few problems here.


First, plastic sheeting is just that - plastic. It tears easily, which makes it unlikely to stand up to rocks in the hard dirt floor of your crawl space, let alone any actual movement if you or a plumber/HVAC technician/etc need to go down there. Second, there’s no useful way to secure it. Every day, we’re in crawl spaces that have essentially a tarp thrown over the dirt - a tarp that usually harbors puddles of water and is torn or bunched up in random spots, leaving the dirt exposed anyway.


The Good



Unlike the glorified tarp, the CleanSpace vapor barrier was created for crawl spaces. The 20mil thick material is inorganic, waterproof, and antimicrobial, meaning it won’t let mold grow. It’s also installed securely to the walls and floor of the crawl space, ensuring total protection.


The key to encapsulating your crawl space is actually sealing it off from the ground. This makes your crawl space a conditioned area, which means warmer, cleaner air travels up through your home. If your crawl space regularly has standing water, a sump pump can be installed in conjunction with the CleanSpace.




SilverGlo insulation is a 2” thick foam board covered by a radiant barrier that not only insulates your crawl space, it actually reflects heat back in to keep the area warmer. The key to SilverGlo is that, like CleanSpace, it’s inorganic, which means it won’t allow mold to grow. SilverGlo panels are installed on crawl space walls in conjunction with the CleanSpace barrier. For extra oomph, you can add TerraBlock insulation to the floors. TerraBlock is a ¾” foam board insulation covered on both sides with a vapor barrier that was designed for rough crawl space floors to add even more protection.




You might think that one of the advantages of fiberglass insulation is its flexibility - it can get jammed into every nook and cranny, where our board insulation can’t. That’s why we also use inorganic spray foam insulation with SilverGlo. FrothPak spray insulation is used in all of those gaps, divots, and corner spaces in the crawl space to ensure total sealing and protection.




No matter what DIY blogs say, not all insulation is created equal. Just like you don’t (usually) carpet a bathroom, you shouldn’t use absorbent insulation in a damp area like a crawl space. If you’re noticing cold floors and think your crawl space is to blame, call to schedule your free inspection and spend the rest of the winter warm and carefree.


our service area

We serve the following areas

  • Algonac
  • Allen Park
  • Carleton
  • Casco
  • Center Line
  • Clinton Township
  • Dearborn
  • Detroit
  • East China
  • Eastpointe
  • Ecorse
  • Erie
  • Fair Haven
  • Flat Rock
  • Fraser
  • Grosse Ile
  • Grosse Pointe
  • Hamtramck
  • Harper Woods
  • Harrison Township
  • Harsens Island
  • Highland Park
  • Ida
  • La Salle
  • Lambertville
  • Lincoln Park
  • Luna Pier
  • Marine City
  • Marysville
  • Melvindale
  • Monroe
  • Mount Clemens
  • New Baltimore
  • New Boston
  • Newport
  • Port Huron
  • River Rouge
  • Riverview
  • Rockwood
  • Roseville
  • Saint Clair
  • Saint Clair Shores
  • Samaria
  • South Rockwood
  • Southgate
  • Taylor
  • Temperance
  • Trenton
  • Warren
  • Wyandotte
Our Locations:

Ayers Basement Systems
2505 S. Waverly Hwy
Lansing, MI 48911
services area map