Two inches of closed cell is not enough for an attic. Attics are above-grade spaces. The Delta T that attics experience fluctuates throughout the year. Especially in summer, attics take on a lot of heat.
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.
Overall, the second layer of insulation plays a crucial role in improving insulation performance, reducing heat loss, and maintaining a comfortable and energy-efficient living space.
The Bottom Line About How Much Insulation You Really Need
Many online experts claim that two inches of closed cell spray foam is enough for any project. These experts present data and charts to demonstrate the efficiency of insulation reaching a reasonable high at two inches.
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.
The dip from R10 to R4 seems odd, as one would expect more R as you travel further north through the zones. Thicker is not better! Doubling the amount of insulation will double the R-Value, but so what? Doubling the insulation from R-19 to R-38 does NOT cut the heat loss in half (50%) it cuts it by around 3%!
This is because the second layer of insulation prevents any possible contact between the live parts and the casing. Therefore, even if the appliance is handled or touched when a fault has occurred, the user is still protected from electric shock.
Yes, an air gap can significantly improve the effectiveness of insulation. This is because air is actually a good insulator in itself. When an air gap is present between the insulation material and a surface, it creates an additional layer of insulation by trapping air in that space.
Thermablok® Aerogel is a revolutionary advancement in thermal technology offering the thinnest insulation available to prevent thermal and cold bridging. Classed as a Super Insulation, Aerogel has the highest insulation value of any known material with the lowest thermal conductivity value of any solid (0.015W/mK).
What Happens If You Compress Blown-In Insulation? Like batts, compressing blown-in fiberglass insulation improves the R-value per square inch while diminishing the overall R-value. Also like fiberglass batts, some amount of compression is OK if the cavity is completely filled.
When you stack new insulation on top of existing attic insulation, the existing insulation is compressed a small amount. This will slightly decrease the R-value of the existing insulation. This effect is most important if the new insulation is more dense than the old insulation.
Walls, floors and ceilings should feel warm and dry to the touch in your home. An indication that there is not enough insulation can be drywall or paneling feeling damp or cold. Conversely, the walls outside of your home should feel cold because insulation stops the heat from escaping.
For insulation rolls and batts, the recommended thickness level is 270mm. This is what you will have to insulate to in a new property, and what you should be aiming to insulate to in an older one. If starting from nothing, you will probably have to buy and install two rolls or batts.
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.
Irritation to skin and respiratory system
Wall insulation solutions like Rockwool are made of ultra-fine fibres. While thermally efficient, they can cause skin and respiratory irritation.
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.
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.
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 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.
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.
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.
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.