NASCLA Accredited Commercial General ContractorThermal and Moisture ProtectionMedium
A contractor is evaluating insulation options for a new commercial building's exterior walls. The design requires a continuous insulation (CI) layer to minimize thermal bridging and achieve a high R-value. The budget is moderate, and installation speed is a factor. Which insulation material would be the most appropriate choice for this application?
- APolyisocyanurate (Polyiso) Boards
- BMineral Wool Boards
- CLoose-fill Cellulose
- DFiberglass Batts
Show answer & explanationAnswer & explanation
Correct answer: A. Polyisocyanurate (Polyiso) Boards
Polyisocyanurate (Polyiso) boards are excellent for continuous insulation applications, offering a high R-value per inch, relatively quick installation as rigid boards, and are a cost-effective solution for achieving energy performance goals.
Why the other options are wrong
- B. Mineral wool boards are good for CI and fire resistance but generally have a lower R-value than Polyiso and might be more expensive.
- C. Loose-fill cellulose is blown into cavities and not suitable for continuous insulation on the exterior of wall sheathing.
- D. Fiberglass batts are typically installed within wall cavities, not as continuous insulation, and have a lower R-value per inch.
Polyisocyanurate (Polyiso) Insulation
A rigid foam board insulation with a closed-cell structure, known for its high R-value per inch, often used for continuous insulation in walls and roofs.
- High R-value per inch (~R-6 to R-7)
- Commonly used as continuous insulation (CI)
- Lightweight and easy to cut/install
- Good fire resistance properties
Memory trick: For 'Continuous Insulation', think 'Polyiso' – it's a 'Prime' choice.