"Should I Remove Insulation from Crawl Space?" is a question we get a lot. This is because many contractors are telling homeowners it is not needed. Is that true? Is crawl space insulation needed, or is it better to remove it?
I understand why some say it is not needed because certain types of insulation may cause more harm than good. Fiberglass insulation between the joists can house rodents. It can also enhance moisture problems that lead to mold and wood rot fungus.
I have even seen fiberglass insulation blown on crawl space walls. We have also removed cellulose insulation that was held up by netting between the joists. But what I feel is even worse is spray foam insulation applied to wet moldy wood. To me, since many contractors don't understand how to properly insulate the crawl space, their default response is just to get rid of it.
Crawl Space Insulation is Key to Energy Efficiency
Insulating Floor Over Dirt Crawl Space
Homebuilders have been insulating the joists of the crawl space for many years. This old school way of insulation is still practiced today. In some cases this type of insulation is fine but humidity and water can wreak havoc. When fiberglass, rock wool, or spray foam attached to the sub-floor becomes wet, it often creates a mold or wood rot fungus problem.
Trapping moisture can happen during a plumbing leak or humid day. Wet wood is not good. Covering the sub-floor does not allow the wood to dry properly. Dirt floor crawl spaces or basements are notoriously damp. Installing a dehumidifier is recommended to control humidity. Sump pumps are used to address flooding and standing water. Neither will be effective at drying wood covered by insulation.
Insulating Crawl Space Walls
So back to the question of "Should I Remove Insulation from Crawl Space?" The answer is yes if it is trapping moisture but then replace it with proper crawl space insulation. We can insulate the sub-floor of the crawl space if the homeowner likes, but what we try to do is insulate the walls of the crawl space.
Building Science Crawl Space Insulation
Water Resistant Wall Insulation
When water-resistant wall insulation is installed properly, it creates a thermal barrier. The foundation thermal barrier is more effective versus the sub-floor thermal barrier in a closed or encapsulated crawl space. If your crawl space is open or vented, sub-floor thermal barriers are recommended.
Wall insulations include foam board and insulation vapor barrier. Both are very effective at controlling crawl space temperatures. Many homeowners don't worry about pipes freezing with a properly insulated and encapsulated crawl space.
Do you need help with crawl space insulation? If so, please contact Crawl Space Ninja or Basement Ninja and we will be glad to help. Also, let us know in the comments below if you'd like to suggest a future blog post.
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