For a homeowner, adding too much insulation to your attic space can have unexpected consequences. In order to know how much insulation is too much, it’s important to know how to insulate different types of attics. This will help you avoid the disadvantages of over-insulating.
Is Your Attic Sealed or Vented?
The first step in determining how much insulation your attic needs is to look at the type of attic in your home. There are two types of attics: vented or sealed.
A vented attic has small vents located at the peaks of the walls in the attic. These vents allow the exchange of heat and air. This is beneficial because it keeps the roof from overheating in the winter. If the roof gets too hot, it can melt snow. The water that runs into your gutters as a result will freeze and form ice dams in the gutters.
In the summer, the vents keep humidity and moisture to a minimum. This protects your roof’s shingles from the damage that those conditions can otherwise cause.
In a vented attic, the insulation gets installed under the attic floor instead of insulating the attic’s walls. The conditioned space is everything below the ceiling insulation.
A sealed attic is one in which there aren’t any vents to allow the exchange of heat and air. In this type of attic, insulation gets installed on the interior walls, including the attic in the conditioned space.
This is beneficial in that the HVAC ducts that run through the attic stay confined to the conditioned space. If there’s a leak in the ducts, the heated or cooled air will still remain inside the conditioned space.
How Does Attic Insulation Work?
Insulation is important because it separates conditioned space from the rest of the home. This means it takes less energy to keep your home cool in the summer and warm in the winter.
A larger amount of conditioned space will require more energy to maintain a consistent temperature. Similarly, a home that isn’t insulated will allow conditioned air to escape the home.
The transfer of heat is commonly called the R-value, and this rating indicates the amount of thermal resistance the attic insulation provides. While there will still be an exchange of heat, a higher R-value means that this transfer is slower.
If your insulation’s R-value is too low, your HVAC system will run more frequently to keep up with the changing temperature in the conditioned space.
What Happens When You Over-Insulate Your Attic?
The optimal R-value for most homes is 30, but you can go as high as 38 if you live in a tropical climate. Anything higher than 38 indicates an over-insulated space. While you might think that too much insulation can’t be bad, there are some significant consequences to consider.
Your Protection Won’t Improve
Adding too much insulation is simply a waste of money. Once you reach a 38 R-value, anything higher won’t really make a difference. It’s more cost-effective to install a radiant barrier to help block more heat from affecting your insulation.
Your Ventilation Might Suffer
When it comes to insulating attics, too much of it can inhibit air circulation in your attic. If more heat remains trapped inside, it can have the same effects that a sealed attic produces. This means damaged roofing and ice dams in your gutter are more common.
Increased Humidity and Moisture
Too much insulation will leave humidity and moisture to accumulate in your attic space. This can lead to mold growth on your walls and insulation. There might also be water damage to the support beams in your home’s roof.
Leave It to the Professionals
Knowing how to insulate your attic can be tricky since you want the optimal level of protection for your home. A professional contractor can offer experience-based suggestions for insulating your home, including which areas to insulate and which types of insulation you should use. Contact an insulation installer in your area to get started.