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.
Mold in the Middle
It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers. That's when mold starts to grow.
As a general guideline, it's advisable to install double layers of thermal insulation throughout your house. Nevertheless, this may not be feasible in all areas due to space limitations. Typically, it's not practical to add two layers of insulation within the walls of your home.
The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.
However, it is possible to have too much insulation. If there is too much insulation, and it comes in contact with the roof sheeting, it can block air circulation, which can lead to condensation, mould and mildew.
Yes, it is possible to put too much insulation in a loft or attic.
Many of us know what causes mould; when moisture is trapped in the rooms of you home. Sometimes, there is insufficient insulation in the walls, so mould grows. However, not many people realise that additional insulation isn't always the answer. In fact, too much insulation can be the secret cause of mould.
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.
Also, when laying down additional insulation, work from the perimeter toward the attic opening. Never lay insulation over recessed light fixtures or soffit vents. Keep all insulation at least 3 inches away from recessed "can" lights, unless they are rated IC (Insulated Ceiling).
You should install two layers of insulation in your attic; wood joists must be covered to allow the air to move. The first layer will sit between the joists, and the second layer will run perpendicular over the joists. The first layer should have the facing against the drywall to act as a vapor barrier.
R19 Insulation offers superior thermal insulation compared to R13. With a typical thickness of 6.25 inches, R19 fiberglass is designed for use in 2x6 wall cavities, making them suitable for colder climates where higher thermal resistance is necessary.
Besides safety concerns, installation inexperience can result in insulation mistakes that can affect both the quality of your insulation and installation. Improper placement can leave gaps and cause energy loss, lessening the insulation's lifespan.
Looking across your attic, if the insulation is level with or below the attic floor joists, you probably need to add more insulation. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough, and adding more insulation may not be cost-effective.
Adding two R-13, 3.5” batts to a 2”x6” (5.5”) wood stud cavity will not provide an R-26. The total of 7” of insulation is reduced in thickness to 5.5” thereby losing the R-value associated with its full thickness.
Conclusion. Attic insulation can last 80 to 100 years, though it loses its energy efficiency benefits with time.
Do I Have To Remove Old Insulation? Unless your insulation is wet, moldy or infested with pests, you don't need to remove it before adding insulation on top of it. ENERGY STAR® recommends that you inspect your insulation for signs of mold, mildew, moisture and pest infiltration before making this determination.
Blown fiberglass insulation scores an R-value of 3.2 to 3.8, making it slightly less likely than rolled fiberglass to prevent the flow of heat into and out of your house. That being said, though, blown fiberglass insulation isn't meant to cover huge areas like rolled fiberglass insulation.
You can use faced or unfaced batting when installing between the roof rafters of finished attic spaces. When using paper or plastic batting insulation, that moisture barrier should face outward toward the attic space. Even if the attic space is unheated, it's typically warmer than the outside air in winter.
Blocked vents in a vented attic will lead to poor energy efficiency, moisture buildup in your attic space, and most importantly, it will lead to mold.
Can I put plywood over insulation in the attic? Yes you can install plywood subflooring directly over the floor joists and insulation on your floor. You need to install rigid insulation boards on top of the attic flooring joists and then install plywood over the top.
Safety concerns: Attics may not be designed to support heavy loads, raising safety concerns about overloading the attic with too many or too heavy items, potentially compromising the home's structural integrity.
Your walls or floors are always cold. Your home is drafty, especially in certain areas. You notice water leaks or moldy insulation, especially in attic spaces.
The PROBLeM wiTh MOLd
Mildew (mold in early stage) and molds grow on wood products, ceiling tiles, cardboard, wallpaper, carpets, drywall, fabric, plants, foods, insulation, decaying leaves and other organic materials. Mold growths, or colonies, can start to grow on a damp surface within 24 to 48 hours.
Now, to answer whether R-Value can be too high, the answer is technically no. The higher the R-Value, the better the insulation will reduce heat transfer. However, a few things to remember when choosing an insulation R-Value.