The most common areas where double insulation layers are employed include the attic (the ceiling that separates the living space from the attic), a pitched roof (the space between the rafters), a flat roof (the area between the floor joists) as well as in suspended 'Armstrong' ceilings.
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.
Mold and Mildew Growth
Having too much insulation in your attic can allow for the accumulation of moisture. This leads to mold and mildew growth, which can be extremely bad for your health.
Removing the old insulation would be more beneficial than leaving it. The older insulation is no longer effective because it has compressed over time. You'll also be able to get a more consistent r-value from the newer insulation because the older insulation is likely variable in height.
Yes you can do this. I've seen blown insulation on top of batts. Batt insulation on top of blown insulation. Both on top of insulation board. In every case, the overall r-value was improved.
R-value is used to judge thermal insulation performance and the higher the number, the better the product's insulating ability. So R19 has better insulating ability than R13. Now R-Value ranges widely across products and home applications. Indeed you will see R60 in some places and R13 in others.
The thermal barrier of a home should consist of a continuous layer of insulation on all sides—including the lowest floor, the exterior walls, and the ceiling or roof. Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half.
However, due to its construction with natural materials, eventually the product will lose effectiveness. Fiberglass insulation typically needs to be replaced 15-20 years into it's life, as it can easily become dirty, wet, moldy, and ineffective if there's a roof leak or water damage of any kind.
At first it may seem odd to add insulation for warmth and then purposely allow cold air to enter the attic through vents, but this combination is the key to a durable and energy-efficient home.
In attics, the facing should point down toward the ceiling below.
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.
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).
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.
Should You Insulate the Attic Floor or Roof Deck? If you are looking for an insulation upgrade that you can see (on your energy bill) and feel (in a home that is more comfortable), we recommend insulating the attic floor, and using radiant barriers on the roof deck.
CAN YOU LAY INSULATION OVER INSULATION? STACKING INSULATION ON TOP OF INSULATION. Adding a new layer of insulation over older insulation can be a good idea if the old insulation is dry and in good condition. However, there are circumstances where you should avoid installing new insulation over the existing layer.
The recommended thickness for attics is typically 12-16 inches. Spray foam insulation: As discussed earlier, the recommended spray foam insulation thickness can vary depending on factors like climate and location. For attics, a thickness of 2-4 inches is usually sufficient.
Maintaining adequate attic ventilation is essential for the overall health of you and your home. Without proper ventilation, you risk mold mildew growth, general deterioration of your roofing system, and even increased respiratory problems due to this moisture accumulation.
The short answer, yes, insulating the attic is an effective way to keep your home cooler during the summer months. While it's a given that the insulation in your attic will keep the home warmer during the winter, it isn't immediately obvious that insulation can also help to keep the home comfortable during the summer.
Reduce excess heat and moisture in attics with proper ventilation. The best way to ventilate an attic and ensure a balanced and functional system is to use continuous soffit or fascia vents (intake) and ridge or hip vents (exhaust).
While loft insulation is an effective way to improve energy efficiency and reduce heating costs, over-insulating can lead to several potential issues. Firstly, over-insulation can lead to poor ventilation in the attic, which can cause moisture buildup and increase the risk of mould growth.
Attic insulation costs anywhere from $1,680 to $3,125, depending on the size of your attic and the material used. On average, most homeowners shell out around $2,380. These costs include the insulation materials and installation by a professional.
The Big Question: Do I Need to Remove Old Insulation Before Installing New? In the majority of cases, removal of old insulation is NOT necessary before adding new.
Because its structure is more complex than single-layer insulation, the cost is relatively high. Additionally, in some cases, double-insulated cables may fail due to spalling between the inner and outer insulation layers.
The U.S. Department of Energy recommends attic insulation levels of R-49 to R-60 for most homes in colder climates, and R-30 to R-49 for homes in warmer climates.