Compare systems by R-value, build-up depth, moisture behavior, fire requirements, cost, and installation quality.
Glasswool Batts
Common use
Ceilings, walls, and suspended timber floors.
Advantages
- Usually cost-effective and widely stocked.
- Broad range for different framing and R-values.
- Well understood in NZ residential construction.
Disadvantages
- Poor fitting or compression reduces performance.
- Can irritate skin/airways without suitable PPE.
- Needs care around penetrations and services.
Polyester Insulation
Common use
Ceilings, walls, underfloor, and acoustic walls.
Advantages
- Easy and pleasant to handle for installers.
- Stable form and good long-term resilience.
- Often includes recycled PET content.
Disadvantages
- Can cost more than entry-level alternatives.
- Range/stock may vary between regions.
- Still requires precise fitting for best results.
Wool Insulation
Common use
Ceilings, walls, underfloor, and acoustic spaces.
Advantages
- Natural fibre option with strong acoustic benefits.
- Comfortable handling and sustainability appeal.
- Popular for healthy-home focused projects.
Disadvantages
- Often higher initial cost than basic batts.
- Correct product selection is important by location/detail.
- Not uniformly available at all merchants.
Rigid Foam Boards (EPS / PIR)
Common use
Under-slab, underfloor, thermal breaks, cavity upgrades.
Advantages
- High thermal performance per mm of thickness.
- Useful where space is constrained.
- Can perform well in targeted assemblies.
Disadvantages
- Needs careful compliance and fire detailing.
- Workmanship around joints is critical.
- Can be costlier than entry batt systems.
Blown-In / Loose-Fill
Common use
Ceiling retrofits and hard-to-access spaces.
Advantages
- Effective for topping up older homes.
- Can reach difficult spaces more easily.
- Useful when removing linings is impractical.
Disadvantages
- Installer quality and method are very important.
- Moisture and ventilation conditions need checking.
- Not suitable for all wall/roof scenarios.