Why Reusing Fiberglass Insulation in Your Crawl Space Could Be a Costly Mistake

Ready to transform your crawl space and avoid costly mistakes? Join us as Michael Church from Crawl Space Ninjas uncovers the truth about reusing fiberglass insulation. Many contractors might suggest it's okay to reuse, but is that really the best practice? We'll break down the types of insulation commonly found in homes—rock wool, fiberglass, and spray foam—and explain why compromised insulation can lead to problems like moisture damage, mold, and reduced effectiveness. Get expert advice on how to handle wet and damaged insulation, especially if you're considering sealing and dehumidifying your crawl space.

We dive into the specifics of why removing old, compromised insulation is crucial, and the best alternatives for both vented and sealed crawl spaces. Learn why subfloor insulation is a necessity for vented spaces due to building codes, and discover the benefits of foam board and insole barrier insulation for sealed environments. Michael shares actionable tips that will help you ensure your home remains efficient and healthy. Don't miss out on these essential insights that could save you time and money in the long run.

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Episode Transcript

Speaker 1 (00:00):
Hey, michael Church Crawl Space Ninjas.
Today we're continuing ourmisconception series about
should you reuse that fiberglassinsulation?
There's a lot of contractorsout there that will reuse
subfloor insulation.
Is that a good idea?
Stay tuned Many times whenwe're talking to homeowners

(00:21):
about properly insulating thecrawl space.
Most homes built today arebuilt with subfloor insulation
that could either be rock, woolor fiberglass.
And then you got some companiesthat are spray foaming the
subfloor and different thingslike that.
Normally by the time we go in toaddress a crawl space, it's got
mold and high humidity and evensome standing water.

(00:42):
So by that time the insulationis already soaking, wet and
dripping and even what we callstalactiting, where you can see
the fiberglass is starting topull away from the insulation
and looks like littlestalactites that are hanging
down from the subfloor.
So you should never reuse thatinsulation.
If it's moist it's already beencompromised.

(01:03):
The R-value has already startedto deteriorate.
Anytime fiberglass gets wet itaffects the R-value.
So what we do in that situationespecially if you're going to
encapsulate the crawlspace, sealthe crawlspace, install
dehumidification and that sortof thing just take that
insulation out, because normallyyou have to get it out in order
to dry out the subfloor andpossibly address mold.

(01:26):
So take the insulation out, bagit and throw it away and then
install a foam board or aninsole barrier insulation on the
walls instead of puttingsubfloor insulation back.
Now if you have an open crawlspace and you have that same
scenario, you can't insulate thewalls.
You need to put subfloorinsulation back because of code.

(01:48):
So if your crawl space isvented, you have to have
subfloor insulation.
If your crawl space is sealed,you can do wall insulation
instead of subfloor insulation,but never reuse fiberglass or
rock wool.
You can reuse foam board,because foam board is actually
designed to be wet and beinstalled below grade, so that's

(02:09):
okay.
If you have to take the foamboard off the wall, you can
reuse it.
Michael Church Crawl SpaceNinja.
We hope you make it a happy andblessed day.
We'll see you later.