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Johns Manville ENRGY 3 Grade 2 Polyiso Roof Insulation Board, 4.2 in. x 4 ft. x 8 ft.
Regular price $74.00Orders start at $399 — combine any items to reach the minimum. Learn more
Johns Manville ENRGY 3 Grade 2 Polyiso Roof Insulation Board, 4.2 in. x 4 ft. x 8 ft.
This is a 4.2 in. thick, 4 ft. x 8 ft. flat ENRGY 3 polyisocyanurate roof insulation board with a closed-cell foam core and glass-reinforced facers, rated Grade 2 (20 psi) per ASTM C 1289, Type II, Class 1. Each board is sold per piece and provides about 32 sq ft of coverage. It pairs with JM multi-ply, single-ply and metal roof systems as part of approved JM Peak Advantage roofing guarantees.
Key Features:
- High R-Value: At 4.2 in. thickness this board carries an LTTR value of 24.9 (hr-ft2-F)/BTU per the published table.
- 20 psi Compressive Strength: Grade 2 rating provides minimum 20 psi (138 kPa) compressive resistance at 10% consolidation per ASTM D 1621.
- Glass-Reinforced Facers: Facers provide rigidity and resistance to indentation and crushing, and are compatible with BUR, modified bitumen and single-ply membrane systems.
- Closed-Cell Foam Core: The closed-cell polyisocyanurate core delivers high R-value per inch and is approved for direct application to steel decks.
- Broad System Compatibility: Compatible with all single-ply systems (TPO, PVC, EPDM) and selected multi-ply BUR, APP and SBS systems.
- Certified Approvals: UL Classified, FM Approved, Miami-Dade County Approved, Florida Building Code Approved, PIMA QualityMark Certified and Title 24 compliant.
- Environmentally Responsible: Produced with a pentane blowing agent with zero ozone depletion and virtually no global warming potential.
Specifications Table:
| Specification | Details |
|---|---|
| Brand | Johns Manville |
| Manufacturer model | 90012663 |
| Sell unit | 1 board, 4.2 in. x 4 ft. x 8 ft. |
| Product line | ENRGY 3 Flat Polyisocyanurate Roof Insulation |
| Material | Closed-cell polyisocyanurate foam core with glass-reinforced facers |
| Color / finish | Tan |
| Nominal size | 4 ft. x 8 ft. |
| Dimensions | 4 ft. x 8 ft., 4.2 in. thick (107 mm) |
| Thickness | 4.2 in. |
| Coverage per unit | Approx. 32 sq ft per board |
| Compressive resistance | Grade 2: 20 psi (138 kPa) minimum |
| LTTR value | 24.9 (hr-ft2-F)/BTU at 4.2 in. thickness |
| Standards | ASTM C 1289, Type II, Class 1, Grade 2 (20 psi) |
| Approvals | FM Standards 4450/4470, UL 790/263/1256, CAN/ULC S704 Type 2 & 3 Class 3, Miami-Dade, Florida Building Code, PIMA QualityMark, Title 24 |
| Service temperature | -100°F to 250°F (-73°C to 121°C) |
| Moisture vapor permeance | <1 perm per ASTM E 96 |
| Installation | Mechanically fastened, urethane adhesive or hot asphalt |
| Intended use | Commercial low-slope roof insulation for multi-ply, single-ply and metal roof systems |
| Product weight, complete sell unit | 25 lb |
Coverage & How Much You Need:
One 4 ft. x 8 ft. board covers approximately 32 sq ft of roof area. Divide total roof area by 32 to estimate board count; boards are typically layered or tapered in combination with other insulation to meet design R-value.
Fit and Compatibility:
ENRGY 3 is designed for use in JM multi-ply (BUR, APP, SBS) and all single-ply (TPO, PVC, EPDM) roofing systems and is approved for direct application to steel decks. Membrane fasteners, adhesives and cover boards are sold separately; refer to JM application instructions for attachment patterns.
Frequently Asked Questions (FAQ):
Q: What is included with this item?
A: One 4.2 in. x 4 ft. x 8 ft. flat ENRGY 3 Grade 2 polyiso insulation board; fasteners, adhesives and membrane are sold separately.
Q: How many boards do I need for my roof?
A: Each board covers about 32 sq ft, so divide your roof area by 32 and add waste allowance for cuts and perimeter fit.
Q: What R-value does this board provide?
A: The published LTTR value at 4.2 in. is 24.9 (hr-ft2-F)/BTU; actual in-place R-value depends on installation circumstances.
Q: How is it attached?
A: It can be installed mechanically fastened, with urethane adhesive, or in hot asphalt, following JM application instructions and local code.
Q: Can it go directly on a steel deck?
A: Yes, the closed-cell polyisocyanurate core is approved for direct application to steel decks.
Q: Is it compatible with single-ply membranes?
A: Yes, the glass-reinforced facers are compatible with TPO, PVC and EPDM single-ply systems as well as BUR and modified bitumen.
Expert Verdict — Reviewed by the SuperArbor Pro Desk
Choose 4.2 in. ENRGY 3 when the design calls for roughly R-25 of continuous polyiso per layer under a single-ply or multi-ply membrane. Follow the JM minimum fastening pattern for the board size and membrane type, and confirm the deck and attachment method with your technical specialist. Pair with a JM cover board where foot traffic or membrane puncture resistance is a concern.
Follow JM application instructions and local building code for attachment; verify deck type and fastener pattern before installation.
Order the Johns Manville ENRGY 3 4.2 in. polyiso roof insulation board today for high-R commercial roof performance.
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