Proper roof insulation is essential for improving energy efficiency and controlling moisture in residential and commercial buildings. Heat loss through the roof can account for 25%–35% of total building energy loss, making it one of the most significant factors affecting a building’s overall energy performance.
Expanded Polystyrene (EPS) rigid insulation solutions from Alleguard provide a lightweight yet durable way to enhance roof performance. EPS insulation products are suitable for both new construction and retrofit projects, offering consistent thermal performance, high R-Values, and long-term moisture resistance. Unlike some other insulation types, EPS insulation maintains its R-Value over time, ensuring lasting performance. The R-Value for our rigid EPS insulation ranges from 3.9 to 5.0 per inch, making it a reliable solution for improving building efficiency.
Alleguard’s manufacturing facilities use steam and cold water to produce EPS insulation. No harmful chemicals like CFC’s, HCFC’s, formaldehyde are used in the EPS manufacturing process eliminating off-gassing and greatly reducing harmful emissions.
EPS Roof Insulation Solutions
Non-Perforated SilveRboard®
SilveRboard® is a non-perforated EPS rigid insulation board designed to supplement batt insulation within roof cavities. Its vapor-resistant barrier helps prevent moisture buildup and improves indoor air quality. Key benefits include:
- Easy Installation: Seams can be taped with vapor barrier tape, creating a continuous, airtight surface.
- Reflective Surface: The double-sided lamination dramatically increases board strength and flexibility.
- Compatibility: Suitable for wood frame, steel frame, and concrete roof structures.
SilveRboard® is particularly effective for creating a higher level of airtightness and vapor resistance in roofing assemblies.
Envirosheet
Designed to be a continuous insulation, reduce thermal bridging, and directly improve building envelope performance, Envirosheet offers a lightweight yet durable insulation solution for both new and retrofit roofing projects. It provides consistent R-Values even in fluctuating temperatures and is resistant to moisture, mold, and mildew. Key features include:
- Cost-Effective: A lightweight and affordable solution for roof insulation.
- Versatile Installation: Can be installed over existing roofing materials or integrated into new roof assemblies.
- Moisture Protection: A dedicated vapor barrier is required when using Envirosheet to prevent moisture infiltration and mold growth.
- Stable R-Value: R3.9 to R4.4 (RSI0.69 to RSI0.77) per inch.
Envirosheet is available in various thicknesses and compressive strengths to meet different project requirements.
Fanfold Roof Cover Board
Alleguard’s Fanfold Roof Cover Board is a non-structural, rigid insulation board with a laminated facer on both sides offering cost effective performance. It is durable, flexible, and is found to have an increased thermal resistance in lower temperatures. Fanfold Cover Board enhances the thermal performance of existing roof insulation by adding an additional insulating layer. It helps reduce energy costs and improves the overall durability of the roof system. Key benefits include:
- Moisture Protection: Functions as a vapor barrier when sealed and taped with an approved vapor barrier tape.
- Easy Installation: Labor to install is typically 50% less per man-hour, and requires less fasteners per sq. ft. than other cover boards.
- Surface Compatibility: Provides a smooth surface for the application of roofing membranes and coatings.
Holey Board
Holey Board acts as the primary thermal barrier within Lightweight Insulating Concrete (LWIC) systems, reducing the weight of the roof assembly while maintaining high R-Value retention. Holey Board is custom cut with factory cut holes offering cost effective performance. Key benefits include:
- Long-Term Efficiency: Excellent R-Value retention for consistent thermal performance.
- Customizable: Custom board sizes, hole sizes and pattern are available for special order.
- Compatibility: Compatible with metal deck, precast concrete or poured in place slab.
Installation Tips for Rigid Board Roof Insulation
Sloped Roof With Attic
Typical attic insulation can be supplemented with Alleguard’s rigid insulation boards.
- Provide wind baffles along the perimeter of the wall to maintain air gap to promote air flow for proper attic ventilation.
- Rigid insulation boards are installed to the underside of roof trusses.
- Overlap the wall vapor retarder onto the face of the SilveRboard®. Tape and seal all joints with approved vapor barrier tape.
- It is important to provide a sufficiently sized air gap around heated penetrations such as recessed lights and heating flues. Allow electrical rough-ins to accommodate for extra thickness insulation and furring strip thickness.
Sloped Roof With Interior Insulation (Cathedral/Vaulted Ceiling)
For cathedral style ceilings, rigid foam boards can also be used to supplement the batt insulation that is found in the cavity to reach higher R-values as can be needed for higher energy efficiency.
- Air cavity is needed on the underside of the roof sheathing to provide adequate ventilation
- Appropriate ridge and soffit vents are needed to make sure minimum level of ventilation are provided for long term performance of the roof assembly
- Place mineral wool batt insulation at the appropriate thickness to fill the cavity between the roof rafters
- Overlap the wall vapor retarder onto the face of the SilveRboad. Tape and seal all joints with approved vapor barrier tape.
Sloped Roof With Exterior Insulation
Cathedral style roofs can also be achieved using exterior insulation which allows for much higher performing roofs that can be used to meet very energy stringent standards such as passive house, net zero, etc. In the following example, High Density (HD) Envirosheet is used in multiple, staggered layers in both the wall and the sloped roof to provide a 2/3 of the insulation value outside of the wood sheathing.
Additional EPS Solutions for Roof Insulation
Tapered Roofing Insulation
EPS tapered roofing insulation is designed for flat and low-slope roofs to improve drainage and prevent water ponding. High design flexibility allows for more optimal sloping and drain placement to meet site specific conditions for more efficient drainage. It can be used for commercial, residential, institutional and industrial flat roof applications. Tapered EPS’s adaptability and energy efficiency help to make it a sustainable alternative for both new and retrofit roof systems, therefore lowering long-term adverse environmental impacts.
- Custom Fit: Customizable to match the roof’s profile and slope.
- Lightweight: Each panel is easy to handle due to the low weight, small size and can be easily cut.
- Enhanced Performance: Protects roofing membranes from damage caused by standing water.
- Compatibility: Can be combined with Envirosheet flat rigid insulation to act as fill to create a hybrid tapered insulation system.
- Material Savings: Up to 50% material savings vs. alternative tapered systems.
Flute Fill
Flute fill insulation, such as Alleguard’s Flute Fill (FL) is custom cut foam used for retrofit applications for metal roofs that are being covered with a new roofing system. Flute fill panels are easy to handle due to the low weight and can be easily cut. These products improve job site efficiency and reduce labor costs.
By providing insulation that is custom cut to match the flute dimensions of metal panels, flute fill improves the R-Values of the roofing assembly. This tailored fit reduces material waste that would otherwise result from on-site cutting, resulting in cleaner installation and reduced labor time.
- High Strength: Enhances the roof system’s ability to resist thermal cycling and wind uplift.
- Customizable: Available in flat or tapered cut configurations.
- Improved Performance: Enhances the overall stability and durability of the roofing system.
Amdeck Insulated Concrete Floor & Roof System
Amdeck provides a stay-in-place EPS formwork for reinforced concrete slab roofs, combining insulation with structural integrity. It is perfectly suited for use with ICF walls or independently with other structural systems. The combination of reinforced concrete slab with Amdeck Pro achieves a thermal resistance of R19 (RSI 3.35), FIIC rating of 30 and ASTC rating of 47+.
Benefits include:
- High R-Value: Enhances thermal resistance and sound attenuation.
- Structural Strength: Improves load-bearing capacity of roof assembly.
- Easy Assembly: Amdeck comes in standardized, lightweight sections that are joined to construct the roof in an easy and fast manner.
Amdeck Eco
Amdeck Eco is designed for low-rise residential applications with longer sections increasing construction speed. The use of dimensional lumber for the joists simplifies the construction by using a commonly available construction material.
Amdeck Pro
Amdeck Pro is designed for commercial applications with compact modular design allowing the forms to be easily transported and installed even in smaller spaces. The forms have embedded polypropylene webs offering even greater temporary construction load distribution to the metal joists.
Additional Benefits
Consistent R-Values: EPS insulation retains its thermal performance over time.
Moisture Resistance: Closed-cell EPS prevents water absorption, reducing the risk of mold and mildew.
Lightweight: Easy to handle and install, reducing labor costs and speeding up installation.
Recyclable: Alleguard EPS products are recyclable and can contribute to U.S. Green Building Council LEED certification points.
Why Alleguard
Proper roof insulation is essential for reducing energy costs, improving indoor comfort, and protecting against moisture damage. Alleguard’s EPS solutions, including SilveRboard®, Envirosheet, and Holey Board, provide superior performance, easy installation, and long-term durability. Architects, contractors, and developers should consider Alleguard EPS products for their next roofing project to achieve enhanced energy efficiency and reduced operating costs.
Explore Alleguard’s full range of EPS roofing insulation products to see how they can improve your next roofing project.