In general, either batt or rolled insulation or blown
Installing new insulation over old is a viable option for keeping your home warm in the winter and cool in the summer. However, the current insulation must be in good condition. It's vital that a professional insulation technician inspect your current insulation before adding another layer.
Loose-fill insulation can be installed on top of old insulation. Whole-house air sealing is a wise idea before adding new insulation, as leaks will reduce energy efficiency and comfort.
As a general guideline, it's advisable to install double layers of thermal insulation throughout your house.
Removing old insulation is generally recommended if it's damaged, contaminated with mold, or infested with pests. However, if the insulation is in decent shape and just needs a boost, adding a new layer on top can be a cost-effective option.
Any reputable insulation installer will thoroughly remove old insulation before putting in the new. However, as a homeowner, you should double-check that they remove all of the old insulation as a first step.
Stacked insulation can impede this airflow, further reducing its efficiency. If your home already has insulation, you might think adding new batts on top of the old ones is a cost-effective solution.
The primary purpose of double insulation is to protect the user from the risk of electric shock. If the first layer of insulation fails for any reason, the second layer acts as a backup, preventing any live parts from becoming exposed.
Installing more insulation in your home increases the R-value and the resistance to heat flow. In general, increased insulation thickness will proportionally increase the R-value.
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.
Never place insulation close to water heaters, oil burners or anything hot. The backing is especially flammable and will be a major fire hazard for your home.
After the insulation is in place you will want to add a vapor retarder, sometimes called a vapor barrier, if you need one. Not every wall does. A vapor retarder is a material used to prevent water vapor from diffusing into the wall, ceiling or floor during the cold winter.
If your building is located in an area with extreme weather conditions, double insulation can be a game-changer. For instance, in regions with harsh winters, double insulation can prevent heat loss, keeping the interior warm and comfortable.
Unless your home was specially constructed for energy efficiency, you can probably reduce your energy bills by adding more insulation. Many older homes have less insulation than homes built today, but even adding insulation to a newer home can pay for itself within a few years.
Provided the existing rolls are in good shape, you can absolutely retrofit batt insulation with blown-in insulation! Materials can even be mixed, such as blowing in cellulose insulation on top of fiberglass batts (or vice-versa).
R13 insulation is generally more affordable, which makes it an attractive option for budget-conscious projects. However, R19 insulation offers better long-term advantages because of its higher R-value.
If the existing attic insulation is an R-19, you may choose to add another layer of R-19. Two layers of R-19 at 6¼ ” thick will achieve a total R-value of 38. So adding an R-19 batt to an existing R-19 batt will give you a total insulation value of R-38.
Vacuum insulated panels have the highest R-value, approximately R-45 (in U.S. units) per inch; aerogel has the next highest R-value (about R-10 to R-30 per inch), followed by polyurethane (PUR) and phenolic foam insulations with R-7 per inch.
In many cases you can add new insulation on top of old insulation, unless the old insulation is wet, mouldy, or vermiculite. If the old insulation is dry but appears to have previously been wet, you should look for the cause and repair the problem.
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.
If the insulation is in good condition, then a new layer can be placed on top without difficulty. However, the application method depends on the type of insulation already in place. For instance, batt, rolled insulation and blown loose-fill fiberglass or cellulose insulation are easily installed over old insulation.
Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half.
While both types provide insulation, R30 is the better option for maximizing energy savings in areas where heat loss or gain is a major concern. For example, R19 may suffice for interior walls, but R30 is more appropriate for exterior-facing attics or floors.