Understanding Continuous Insulation
Energy standards were the driver behind the use of Continuous Insulation (CI) making the application mainstream. Since 2007, ASHRAE 90.1 (American Society of Heating, Refrigeration, and Air-Conditioning Engineers) has required CI. Thirty-five states have mandatory statewide commercial energy codes that meet or exceed that standard.
ASHRAE 90.1 defines continuous insulation as:
ASHRAE 90.1 defines continuous insulation as:
“Insulation that is continuous across all structural members without thermal bridges other than fasteners
and service openings. It is installed on the interior, exterior, or is integral to any opaque surface of the
building envelope.”
The primary function of CI is to improve energy performance and provide a cost-effective solution for rigorous energy code requirements. The benefits of CI extend beyond energy savings. Properly qualified and installed CI products serve as air- and water-resistant barriers. Certain CI products have been designed to improve structural integrity in wall assemblies. Certain CI products can be used as a water-resistive barrier behind cladding, offering water protection and thermal performance in one product.
Types of CI:
Expanded polystyrene (EPS), Extruded polystyrene (XPS), Polyisocyanurate foam (Polyiso) and Mineral Wool.Expanded polystyrene (EPS):
EPS most widely in insulated concrete forms and structural insulated panels. EPS has lower R-value of the three most common types of rigid-foam insulation, around R-4 per inch but, it often costs less. EPS is suitable for ground contact and can be treated to resist insects. If you plan to use it under slab, make sure to check the compressive strength for the particular use. EPS is considered semipermeable to water vapor, so it does not create a vapor barrier.
Features and Benefits:
- Designed for use as wall sheathing, basement, foundation, and roof insulation
- R-value 3.6 – 4.0 per inch
- Semipermeable to vapor
- Moisture resistant
- Recyclable
- Long-Term Thermal Resistance, time-weighted average of the foam’s R-value
- No CFCs, HFCs and HCFCs in the production process
- Available in multiple thicknesses
Polyisocyanurate Foam Board (Polyiso):
Polyiso panels have the highest nominal R-value, R-5.7 to R-6.5 per inch. Polyiso starts as liquid foam spray applied against a substrate to form a rigid panel; all ISO panels are faced. Foil-faced ISO panels are considered vapor impermeable; fiberglass faced panels and can be used without creating a vapor barrier. Polyiso is not rated for ground contact.
Features and Benefits:
Features and Benefits:
- Designed for use as wall sheathing, basement, and roof insulation
- R-value 5.7 - 6.5 per inch
- Vapor impermeable
- Excellent fire test performance
- Moisture resistant
- Long service life
- Zero ozone-depletion potential and negligible global-warming potential
- Available in multiple thicknesses
Extruded Polystyrene (XPS):
Easily recognized by its blue, green, or pink color, XPS falls in the middle of the three types of rigid-foam insulation in both cost and R-value (about R-5 per inch). XPS comes unfaced or with multiple plastic facings. Unfaced 1-inch thick XPS has a perm rating of around 1, making it semipermeable. Thicker, faced XPS is stronger and can have a lower perm rating, but it is still considered a vapor retarder, not a vapor barrier.Features and Benefits:
- Designed for use as wall sheathing, basement, foundation, and roof insulation
- R-value 5.0 Per inch
- Semipermeable
- Moisture resistant
- Some products have been formulated with a low Global Warming Potential blowing agents
- Long service life
- Available in multiple sizes and thicknesses
Mineral Wool:
Mineral wool is an ideal insulating material. It’s naturally non-combustible, it will not burn or release smoke. This is especially desirable in high-rise buildings. Mineral wool insulation may assist with helping assemblies pass the NFPA 285 fire test.Features and Benefits:
- Designed for use as wall sheathing, basement, roof, and wall insulation
- R-value 3.0 – 3.3 per inch
- Fire resistant, Non-combustible
- Vapor permeable
- Moisture resistant
- Reusable and recyclable item
- Excellent noise reduction and sound absorption
- Available in multiple thicknesses
For answers about where and when to use different types of continuous insulation products contact your local White Cap.
