What insulation board is best?
Which Insulation Board is the Best?
Rigid Foam Insulation Overview
In both residential and commercial settings, the most commonly used foam insulation boards are Polyiso (polyisocyanurate), EPS (expanded polystyrene), and XPS (extruded polystyrene). Each type boasts unique characteristics, R-values, and compressive strengths. Let’s explore rigid foam insulation in-depth.
Polyiso Insulation
Polyiso, often abbreviated as PIR, stands out as one of the top-performing foam boards available today, providing the highest R-values for minimal thickness. This insulation type can effectively replace glass wool and mineral wool across various applications.
Commonly found in stud walls, floors, cavity walls, attics, and external walls, Polyiso is also gaining traction in the flat roofing sector of commercial buildings. Specialized cloth-faced or glass tissue-faced Polyiso is now used in high-rise buildings to replace older asbestos roofing materials from the 1980s. Architects favor Polyiso for its moisture resistance, strength, and superior R-values per inch, making it best-in-class for intended applications.
For projects requiring airtightness, Polyiso insulation can be seamlessly taped and sealed with airtight membranes to ensure an airtight structure while achieving an AAA rating for insulation values.
Installing this insulation in stud walls is straightforward. Use a box knife or carpenter's handsaw for cutting. For the cleanest edge, consider scoring the foil face before cutting. When measuring openings for installation, allow for an extra 2-3 mm for a snug fit, which reduces air leaks. This installation method applies to attic floors, crawlspaces, basements, and external walls.
EPS Foam Insulation
EPS board insulation is among the less efficient rigid board insulations today. Nevertheless, it is known for its high compressive strength, making it ideal for parking areas or floors that bear heavier weights. EPS insulation is widely used in passive housing, particularly in foundations, as it is an effective and cost-efficient method.
Expanded polystyrene board is easy to cut, and lacks a foil layer, so there’s no need for scoring. However, caution is essential around naked flames, as EPS is flammable and produces hazardous black smoke when burned. If used properly, EPS performs exceptionally well without diminishing over the building's lifecycle.
XPS Insulation Board
XPS is visually similar to EPS but provides greater strength, lightness, and compressive strength. Products like Pink insulation foam FOAMULAR 250 XPS offer higher R-values, although they come at a cost—typically 20-30% more than EPS. XPS is prevalent in commercial and industrial sectors where compressive strength is a critical requirement.
Like its counterparts, XPS is lightweight and easy to cut. Both XPS and EPS are closed-cell insulations, ensuring they retain insulation values over time, unlike Polyiso which may degrade after about 30 years.
Brands and Manufacturers
Polyiso: Notable brands include R-Max, Hunter, Owens Corning, Johns Manville, and Dow.
XPS: XPS insulation is manufactured by Pactiv, Dow, Johns Manville, and Owens Corning, with Styrofoam from Dow being a prominent choice in the market.
Decai offers additional products and information; check it out!
Understanding Rigid Board Insulation
Proper insulation is crucial for improving a home's energy efficiency. The U.S. Department of Energy estimates that heating and cooling account for nearly half of total energy use in homes. While investing in efficient heating technologies helps, inadequate insulation will still increase energy use.
Rigid board insulation, a relatively new product, is durable, easy to install, and improves thermal efficiency in even the oldest, draftiest homes. If high energy bills persist despite thermostat adjustments and upgraded appliances, consider retrofitting your insulation. This insulation type can help save up to 40 BTUs of energy for each BTU consumed by your heating and cooling systems, potentially improving energy efficiency by up to 70% in older homes.
What is Rigid Board Insulation?
Commonly used insulation materials include fiberglass, cellulose, and natural sheep wool. However, rigid board insulation is made from dense foam types, including polyurethane, polystyrene, and polyiso. Due to their chemical structure, these foam types are classified as "closed-cell," offering stronger and more durable insulation compared to the more frequently used open-cell products.
Rigid foam insulation comes in 4 foot by 8-foot sheets with thicknesses ranging from ½ inch to 2 inches, providing higher R-value ratings than open-cell alternatives.
Applications of Rigid Foam Board Insulation
Foam insulation boards can be utilized in virtually all areas requiring insulation: foundations, basements, walls, roofs, and attics. In above-grade applications like walls and ceilings, rigid foam insulation reduces thermal bridging and enhances energy efficiency. For foundation walls or below-grade basements, this insulation helps avoid moisture buildup.
Polyiso foam generally offers the best insulation capacity with an R-value of 6.5 per inch, using water as the blowing agent, making it environmentally friendly. However, due to its water absorption properties, it is unsuitable for below-grade applications.
Prioritize low-toxicity flame retardants, such as TCPP, when selecting rigid foam products. Avoid those containing harmful chemicals like polybrominated diphenyl ethers (PBDEs).
Quick Comparison of Rigid Foam Board Insulation Products
Expanded Polystyrene Board (EPS) Insulation
- Pros: Cost-effective, doesn’t deplete the ozone layer, water-resistant at higher densities
- Cons: Lower density options may not be fully water-resistant; lower R-value
- R-value: 3.6 to 4.2 per inch
- Cost: $0.31 per square foot for 1-inch thickness
Extruded Polystyrene Board (XPS) Insulation
- Pros: Strong, more water-resistant than EPS, suitable for below-grade applications
- Cons: Often contains strong chemical flame retardants; blowing agents affect the ozone layer
- R-value: 5 per inch
- Cost: $0.47 per square foot for 1-inch thickness
Fiberglass Rigid Board Insulation
- Pros: Higher R-value compared to traditional fiberglass batt insulation, easy installation
- Cons: Not moisture-resistant, requires a vapor barrier
- R-value: R-11 for 3.5-inch board
- Cost: $1.25 per square foot
Graphite Polystyrene Board (GPS) Insulation
- Pros: Graphite improves thermal performance, increased vapor permeance
- Cons: More expensive
- R-value: 4.5-5 per inch
- Cost: $14 to $16 per board
Mineral Wool Rigid Board Insulation
- Pros: Natural, fireproof, no off-gassing
- Cons: Installation dangers, airborne fibers can be harmful
- R-value: 4.2 per inch
- Cost: $0.50 per square foot
Polyiso Rigid Board (ISO) Insulation
- Pros: Highest R-value among foam products, eco-friendly blowing agent, no harmful flame retardants
- Cons: Not suitable for below-grade use due to water absorption
- R-value: 6.5 per inch of thickness
- Cost: $0.60 per square foot at 1-inch thickness