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.
Depending on where you live and the part of your home you're insulating (walls, crawlspace, attic, etc.), you'll need a different R-Value. Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces.
Aerogel insulation offers the highest R-value of any insulating material at less weight and thickness—ideal for construction, refineries, pipelines, and thin-gap thermal barriers.
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.
They are available in widths suited to standard spacings of wall studs and attic or floor joists: 2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products. Loose-fill insulation—usually made of fiberglass, rock wool, or cellulose—comes in shreds, granules, or nodules.
The average recommended level is 14 inches of R49. In Zone 2, the average minimum requirement for attic insulation is 9 inches of R30 fill. The average recommended level is 17 inches of R60. In Zone 3, the average minimum requirement for attic insulation is 9 inches of R30 fill.
Duct Insulation
| Duct Insulation - Recommended R-values by Climate and Duct Location |
|---|
| Climate | Attic | Unheated Basement or Crawlspace |
| Warm - cooling and minimal heating | R-4 to R-8 | R-2 to R-4 |
| Mixed - moderate heating and cooling | R-4 to R-8 | R-2 to R-8 |
| Cold | R-6 to R-11 | R-2 to R-11 |
Understanding the R- and U-Values of Insulation
| Rated R-Value and Thickness of Insulation* |
|---|
| R-Value | R6 | |
|---|
| Insulation Thickness | 1.75" | 2.5" |
| *All listed thicknesses are approximate and may vary by +/- 0.5 inches. |
The first-generation Audi R8 launched in the U.S. market for the 2008 model year. The R8 is a two-seat sports car that's based on the Audi Le Mans Quattro concept car. The first R8 models came standard with a V8 engine and were available with a V10.
The duct has R6 insulation which contains 33% more insulation than the standard R4. 2 product. This additional insulation provides greater thermal efficiency to save energy. The product is also covered in a heavy duty, silver jacket for durability.
The basic recommendation from insulation contractors is that you should add one to three inches of insulation to your ductwork. Here are the relative values: 1 inch of insulation: R-value of 1.9. 1.5 inches of insulation: R-value of 3.5.
R-Value measures how well insulation can resist heat flow. When HVAC contractors describe the R-Value of your ductwork, we're actually talking about the insulation around your ducts and how well it prevents heat from entering or escaping your ducts.
If your attic has fiberglass material,
5 inches gives about an R-11 insulation level, 8 to 9 inches around R-19, 12 inches R-26 and 13 to 14 inches is around R-30.
How many inches is r11 insulation?
| Thickness (inches) | R-Value | Cost (cents/sq. ft.) |
|---|
| 3 1/2 (high density) | 15 | 34-40 |
| 6 to 6 1/4 | 19 | 27-34 |
Too often, flex ducts are not installed properly, and they end up kinked, bunched up, undersized, or sagging. These issues can cause increased resistance in the duct system, resulting in too little airflow reaching a building's heating and cooling equipment.
For example, a six-inch diameter, nominal R-8 flex duct has an actual R-value of only 5.62 not counting surface films. With the film resistances the total R-value of 6.45 is 19% less than the nominal value. For R-11 ducts (six-inch diameter) the R-value with films is only 7.81, 29% less than the nominal value.
The ducts are exposed to the same cold, heat and humidity that exist on the outside. Insulating them is essential in colder climates, optional in milder ones and necessary in humid climates to prevent condensation.
- General Formula to Calculate Minimum Insulation Thickness Required to Prevent Condensation,t= k * R{(T1 - T2)/ (T3 - T1)} ,
- Where,
- t = Insulation thickness (in)
- k = Thermal conductivity.
- R = Surface temperature resistance.
- T1 = Dew point temperature (°F)
- T2 = Operating temperature (°F)
