One of the most common defects we come across – and usually in nicer homes – is insulation that has been installed upside-down. In particular, paper faced fiberglass batts are always the culprit. This is the type of insulation that probably immediately comes to mind when you hear the word “insulation”… long, rectangular batts (usually pink, white or yellow) with a brown paper facing that exists as a vapor barrier. It can lead to a host of problems when improperly installed, and we’ll go over the most common issues and the basic rule for installation so you can check the insulation in your own home and (hopefully) have it corrected if need.
But first of all, let’s begin with a truth that most people either aren’t aware of or don’t want to admit. With the many innovations that have come along in the world of insulation in recent years, fiberglass batts are no longer a very good option for most applications. There are now a number of superior products – all of which can be used in areas where fiberglass batts long reigned supreme – and they should be used. As with most things, it takes quite a while for products to really “catch on”and for contractors to become completely comfortable with the installation, and that’s one of the reasons fiberglass batts are still so popular despite the availability of several far better products.
For many years, contractors and DIY homeowners have been installing batt insulation and have loved its ease of installation and low cost. Closed cell spray foam (arguably the best product available today, depending on the application) isn’t nearly as easy to install and is quite a bit more expensive, so it isn’t the go-to option for most people. Even mineral wool, which also comes in batt form and is easy to install, is a little less familiar and a little pricier. Old habits die hard, and that axiom rings true for fiberglass insulation as it does with so much else. You don’t have to go all-or-nothing with insulation to achieve a good result, though. One fairly popular method nowadays is having one inch of spray foam applied to create a water and air-tight barrier, along with increased rigidity, and then to fill the rest of the cavity with another, less expensive type of insulation.
So, back to upside-down batts and why they’re a problem… Remember how the paper facing of the insulation acts as a vapor barrier? That’s important because a lot hinges on that barrier being installed on the proper side (and it often isn’t). The simple rule for faced batt insulation is that the brown side should always face the conditioned side of the home. Think of the house as a box you’re looking at from the outside, and then envision all of the brown (the vapor barrier) facing inward. If the insulation is in an unfinished basement, a crawlspace or a drive-under garage, the brown should be facing upward and not visible when you’re inside and looking up. If it’s in an unfinished attic, the brown should be facing down and, again, not visible if you are looking at it from within the attic. If it’s in the exterior walls surrounding the main floor(s), the brown should face the interior and be visible if you were to remove the drywall. Pretty easy, right?
You’re likely wondering, if this rule is so simple, why is it so hard for people to understand and follow? Well, one reason is that many people – even contractors – simply don’t know this rule or get confused when they try to remember the direction the insulation should face. The primary reason, though, is that people are so used to installing batts in wall cavities where the brown side should be visible that they just install it that way regardless of the location. It’s also much more pleasant to touch the paper faced side than the itchy, irritating fiberglass, and the brown side has tabs that conveniently fold over to easily staple the batts to studs, joists and other framing members. Even people who know the simple rule we just went over have a tendency to take the easy road and trust it won’t lead to any major issues in the near future, and professionals know that the average homeowner will have no clue that the way they installed their new insulation is improper.
OK, so you’re probably wondering why this rule exists. Why does the vapor barrier need to be facing the conditioned side of the home, and what, exactly, can happen if it’s installed in reverse? Because the vapor barrier blocks water vapor, air that contains vapor and gets into the insulation can condense if there’s a temperature difference (as there always is between finished and unfinished spaces). Once that happens, the condensation won’t have anywhere to go since there’s either sub-flooring above or ceiling material below, so it becomes trapped and often doesn’t quickly evaporate out. Over a long enough period of time and that continually happening, the insulation can compress, lose its R-value and even become a breeding ground for mold and other contaminants. To make matters worse, the paper facing has a black coating, so you likely wouldn’t even notice this happening until it has caused the insulation to sag or fall from a floor structure or drastically compress in an attic. Vented crawlspaces that are naturally prone to high moisture levels are especially susceptible to damaged, falling batt insulation, and we unfortunately see it all too often during inspections. To make matters worse, the batts are usually just friction fitted into place without any wring or other supports whatsoever. The only saving grace to the insulation being able to fall is that it won’t stay pressed against the subfloor where the condensation can lead to eventual rot of the wood floor structure. I often think of falling insulation in vented crawlspaces as alarms… when the batts fall, you know you have a problem and may want to check out your floor structure!
Take some time to walk through your house to check the insulation. If you have fiberglass batts in your basement ceiling, crawlspace floor or attic, make sure that you can’t see the brown side. If you can, gently pry away some of the sides to look around and make sure there isn’t any mold growth or wood/drywall deterioration. You may not have a glaring issue now, but it wouldn’t be a bad idea to budget for a reputable insulation contractor to evaluate what you have and to make recommendations for repairs since it’s only a matter of time before problems do develop. This won’t only prevent possible long-term damage; it will help improve energy efficiency, comfort and value. The bottom line: fiberglass batts aren’t all they’re cracked up to be, and you’d be wise to make sure yours are at least properly installed.
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