Is it possible to over-insulate your house? Yes! It is possible to over-insulate your house so much that you block nearly all ventilation, and it simply cannot breathe.
In fact, adding too much insulation to your walls can lead to problems such as poor ventilation, mould growth, and condensation. This is because thicker insulation can block airflow and trap moisture, leading to indoor air quality issues and even structural damage.
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.
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.
R13 is about 92% reduction in heat transfer. R19 is about 2-3% better than R13. It's an exponential decay in heat transfer, so you'll be fine with it for a garage. Use the thicker stuff for the attic to reduce transfer from the attic to the garage.
All materials having the same R-value, regardless of thickness, weight, or appearance, are equal in insulating power. There are times when more than one layer of insulation will be used. An example of this is in an attic. If the existing attic insulation is an R-19, you may choose to add another layer of R-19.
R15 insulation offers slightly better thermal insulative properties than R13. Some of its formats are a fraction of an inch thicker than R13, making it more effective at helping with energy efficiency. However, the difference is minimal. R15 is slightly thicker than R13 for spray foam and blown-in cellulose.
Leaving Too Many Gaps
One of the biggest problems DIY homeowners face is leaving too many gaps in their insulation. Gaps or insulation that isn't secured correctly can leave the building structure open to air and moisture leaks. Spray foam insulation is best for reaching into small cracks and any areas left open.
However, insulation can start falling from fiberglass batts after 15 to 20 years, so if your insulation was installed in batts well over a decade ago, it might be time for an inspection or a home energy audit.
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.
Fiberglass and rock wool batts—2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.
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.
Every type of bulk insulation in common use will block heat equally well whichever way it is installed. EXCEPT… some insulation includes a moisture barrier, and that must be installed right-way round to prevent moisture problems. But the insulation itself works both ways.
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.
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.
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.
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.
If you do not like the sensation of dirt or dust on your skin, you will want to wear gloves and cover exposed skin. The dust of cellulose can still be hazardous for your eyes and lungs. If you are near cellulose being installed and do not wear a mask, you will inhale dust and irritate your lungs.
The first layer should have the facing against the drywall to act as a vapor barrier. (The general rule for insulation is that the facing always goes toward the conditioned space.) The second layer of insulation should be unfaced so that moisture doesn't collect between the layers.
What are the disadvantages of R15 V3? The disadvantages of R15 V3 can include its limited storage space, aggressive riding posture, and relatively high maintenance costs compared to other motorcycles in its segment.
Excellent Thermal Performance Owens Corning™ R-15 EcoTouch® insulation is specifically engineered to solve the efficiency problems of exterior 2x4 walls. “High density” means more fibers per square inch. It delivers a higher R-value per square inch in less space than standard insulation products.
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.