Thermal Resistance: R-21 polyiso boards offer higher thermal resistance compared to R-19, which makes them more effective at reducing heat transfer in colder climates.
Excellent Thermal Performance Owens Corning™ R-21 EcoTouch® insulation is specifically engineered to solve the efficiency problems of exterior 2x6 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 a measure of insulation's ability to resist heat traveling through it. The higher the R-Value the better the thermal performance of the insulation.
R19 insulation is a thicker, more robust option—offering higher thermal resistance. Commonly used in colder climates, R19 is well-suited for 2x6 wall assemblies, floors, ceilings, and attics. Benefits: Provides superior thermal protection, contributing to lower energy bills and enhanced comfort in colder regions.
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.
Key Differences: Thermal Resistance: R-21 polyiso boards offer higher thermal resistance compared to R-19, which makes them more effective at reducing heat transfer in colder climates. Thickness: Both R-19 and R-21 polyiso boards are compact by offering high R-values per inch.
The thinnest insulation material currently available on the market is the 10mm Aerogel blanket. Its manufacturing technology is highly interesting, and its appearance resembles frozen smoke. For some, aerogel is synonymous with time frozen and suspended in space.
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.
Foam Board or Rigid Foam
Foam boards -- rigid panels of insulation -- can be used to insulate almost any part of your home, from the roof down to the foundation. They are very effective in exterior wall sheathing, interior sheathing for basement walls, and special applications such as attic hatches.
The most common application of R19 Insulation is in a vertical wall framed by 2×6 studs. As mentioned above this is a common code requirement in some parts of the United States. R19 Insulation can also be used in other areas around the home, including floors and crawl spaces.
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.
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.
It's more efficient to use a higher R Value rated product in the upper levels of your home, such as the attic and in rooms with particularly high ceilings - this makes sense if you consider that heat tends to rise.
Insulation to Use
For 2x4 walls, use R-13 or R-15 insulation. For 2x6 walls, use R-19 or R-21 insulation.
By our rough estimate, for a garage heated consistently throughout the winter, insulating four walls, garage doors, floor, and ceiling to R-19 would result in about $1050/year in energy savings!
When comparing R13 to R21 insulation, the variance represents a substantial difference in thermal resistance. Moving from an R13 to an R21 insulation means gaining a higher resistance to heat loss, contributing to a more energy-efficient and comfortable living space.
R-Value and Exterior Walls
According to the U.S. Department of Energy, R-values for exterior walls in colder climates should be at least R-13 to R-23. In milder climates, a lower R-value may be sufficient. For example, in a moderate climate, an R-value of R-13 to R-15 is typically recommended.
If you live in a mixed climate – hot and humid with several heating months in the winter, you probably need a vapor retarder. Specifically, if you live in climate zones 4C (marine), 5, 6, 7 and 8. Not sure your climate zone? You can check here.
EPS is most commonly used. This is the main insulation - it is normally made of either expanding polystyrene or mineral wool. Technologies such as phenolic resin insulation are also available. All of these materials are used to prevent heat escaping through walls.
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.
It is recommended to have an external wall insulation thickness of 100mm to achieve better thermal efficiency and reduce the U-value by 0.3W/m2K.
The best insulation for walls when it comes to new build homes or remodels is going to be Nu-Wool, foam board, or open cell spray foam.
For example, if you need extra soundproofing or don't want to spend time installing a separate vapor barrier, then face may be the best option for you. However, if cost savings are more important than convenience, then unfaced may be the better choice in this case.
Fibreglass insulation is considered the cheapest and most effective UK insulation option. It's made of glass fibres and is available in batts, rolls, or loose-fill form. Fibreglass insulation is widely used in residential and commercial buildings due to its affordability and effectiveness in reducing heat transfer.
High R-value: Because foam board insulation has a greater R-value than standard fiberglass/batt insulation, it is more effective at insulating and decreasing heat loss.