Skip to main content
Fix Your Nasty, Energy-Wasting Crawl Space CleanSpace crawl space encapsulation is the solution you need.

A dry, healthy home starts here.

Rotting Insulation In A Crawl Space

mice waste in fiberglass insulation from a crawl space

Pest Control Alert!

Old fiberglass insulation makes a great home for rodents, how love to nest inside of this warm, soft material.

Keep an eye out for droppings and other waste left behind as they live, breed, and die in your crawl space.

More about Pests In The Crawl Space

All over North America, it's customary to install fiberglass insulation within the floor joists in the crawl space.

The objective is to keep cold from the crawl space out of the main area of the house and to dampen echoing sounds from foot traffic over the space.

However, as building science develops, homeowners are discovering that there are many shortcomings.

Limitations Of Fiberglass In The Floor Joists

  • Soaks up humidity and moisture, which can cause it to sag and fall to the floor
  • Becomes the home for mice and rats
  • Can encourage mold and rot within the joists
  • Does not protect utilities, pipes, and air ducts stored within the crawl space from cold

At Basement Systems, we recommend insulating the crawl space walls and floors with waterproof insulation. The most effective options will also provide a vapor barrier on insulated surfaces, protecting your home from moisture penetration from the walls and floors.

Get a Free Estimate

At Basement Systems, we specialize in crawl space environments! Our experts have successfully repaired and upgraded hundreds of thousands of crawl spaces and basements worldwide!

Meet with one of our experts for at no charge! Our free, no-obligation crawl space repair estimate includes an on-site inspection, a professional consultation where we answer any questions you may have, and a customized cost estimate for your system. To schedule your appointment, contact us by phone or e-mail today!

Foam insulation for a crawl space insulation job

Insulating Your Crawl Space

Waterproof insulation will hold up against groundwater flooding, plumbing leaks, and the sometimes humid environment in a crawl space.

When installed in an unbroken sheet on the walls and floors, it can also serve as a vapor barrier.

We have many insulation options that are appropriate for craw spaces of all types -- including our highly efficient SilverGlo™™ Foam Insulation.

More about Crawl Space Insulation

How Is Fiberglass Insulation Saturated?

Most commonly, fiberglass insulation is damaged by a damp, humid environment. Fiberglass soaks up water like a sponge, holding it inside its material.

This most commonly occurs in three scenarios:

A Flooded Crawl Space

If your crawl space is flooding, the space will be filled with moisture and humidity. This may occur as plumbing leaks (which can go unnoticed for months or longer), or as groundwater enters through the walls, floor, and where the wall and floor meet.

A Vented & Unsealed Crawl Space

Contrary to their purpose for existing, crawl space vents rarely help to dry a crawl space. Hot, humid air entering a crawl space will quickly cool, leading to condensation on insulation and other surfaces.

An Unvented & Unsealed Crawl Space

Moisture also enters a crawl space through the dirt floor, as well as through the pores of concrete. So a crawl space that is unvented will still be damp -- even with no groundwater leaking.

The solution to a wet crawl space is to keep all moisture out -- which can be accomplished by sealing and dehumidifying the space.

More about Sealing A Crawl Space

What Does Wet Fiberglass Mean For Your Home?

Wet fiberglass insulation is the result of a much larger issue in your home -- and the symptom of many more issues to come. If you have fiberglass in your home that's weighed down with moisture, it should be removed and replaced.

Fiberglass that's waterlogged has the following disadvantages:

Crawl space fiberglass insulation that's dripping with condensation

Loss Of Insular Value

When fiberglass insulation becomes wet, it loses its insulation properties and becomes useless. Additionally, it tends to compress and become weighed down, eventually falling off the floor.

The humid conditions that cause fiberglass to reach this level of moisture will generally not abate unless all sources of moisture are eliminated. And once the insulation begins to sag down, it's no longer providing any benefit for you.

Building Air Quality also states that wet fiberglass that is not dried out will "provide an ideal substrate for microbial growth". This is not helping!

Rotting crawl space floor joists in contact with wet fiberglass

Moldy, Rotting Wood

Fiberglass insulation is porous and cottony -- and soaks up insulation in much the same way that a cloth or sponge would.

Once the moisture is within the fiberglass, it can hold it there indefinitely, until dry conditions are present.

If the fiberglass is pressed against wood surfaces such as floor joists, then the wood will, in turn, soak up the moisture.

Over time, the wood will begin to rot, grow mold, and decay. If left unaddressed, this can develop into potentially serious structural issues within the home.

rotting insulation in a crawl space

A Mess In The Crawl Space

Eventually, the space will begin to look like a disaster area! Wet, moldy fiberglass will sink to the ground, wood will rot, and the air will be filled with a musty smell.

Animals such as mice, termites, carpenter ants, and many more will be attracted to the dark, warm space, the rotting wood, and the fiberglass insulation (aka "nesting material"). Coming in through the vents, they will be more than happy to spend many generations within your home.

This is certainly something you'll want to avoid! Imagine what it would take to pay a contractor to enter a narrow, disgusting, unhealthy, moldy crawl space to rip out and replace the moldy, rotting wood!

We Can End Your Crawl Space Moisture Problems!

At Basement Systems, our network of more than 300 Certified Crawl Space Specialists has the training, equipment, and experience you need to transform your crawl space into energy efficient, dry, valuable space. Our warranted system can be installed quickly in your home -- often in less than a day.

For a free crawl space estimate, contact us by phone or e-mail today! We'll get you in touch with the locally owned and operated dealer in your neighborhood.

Your free estimate will include an on-site professional inspection and measurement, a consultation where we answer any questions you may have, and a free, no-obligation written cost estimate! Before our visit, we'll also mail along a copy of our full-color, informative crawl space book!

We serve throughout Canada and the United States -- including in your neighborhood! Contact us today to get started on a healthier home!

Looking for a price? Get a no cost, no obligation free estimate.

get a free estimate
Quality, Innovation, Patents, Awards

Our innovative and forward-thinking approach to designing products has solved wet basement problems that the basement waterproofing and crawl space industry has faced for decades, and our patented sump pump systems are the smartest and most reliable. Plus we listen to our customers and respond accordingly! Basement Systems Inc. has been awarded 24 Patents and 19 Innovation Prizes on waterproofing products we use every day, including a battery back up sump pump system. This approach ensures the best waterproofing systems and solutions available.