Following H1 energy efficiency changes, building from the ground up has required a fresh approach.
Changes to the New Zealand Building Code on H1 Energy Efficiency represented significant advancements in energy efficiency considerations in construction, requiring a refreshed approach to building from the ground up.
Construction professionals and companies have had to adapt to the requirements and remain not only compliant but innovative and efficient in their efforts when building from floor to ceiling. For builders and installers, this has meant changes to the way insulation is specified and installed, with changes to underfloor, roof, and wall insulation requirements within the new edition of H1/AS1 and H1/VM1 for housing and small buildings (under 300m2).
Underfloor insulation presents particular challenges in New Zealand’s varying climate conditions. Traditional bulk insulation in suspended floors can suffer from moisture accumulation, settling, and thermal bridging through framing members. Modern practice increasingly favours rigid foam insulation boards that provide consistent thermal performance while resisting moisture penetration.
For slab-on-ground construction, perimeter insulation becomes critical for thermal performance. Rigid foam insulation around slab edges prevents thermal bridging to the ground while maintaining structural integrity. Under-slab insulation, while more expensive, dramatically improves thermal performance and justifies the investment in energy-conscious builds.
EXPOL’s next generation, high performance insulation range was specifically designed to meet and exceed the new insulation standards introduced on 01 May 2023.
These slab insulation products are designed to reduce carbon footprint and deliver dryer, warmer, healthier and environmentally friendly spaces.
The company designed three Under Concrete Floor Systems as a result of the H1 changes: slab on grade, waffle pod raft slab and a high performance slab.
Wall insulation systems have evolved beyond simple cavity fill approaches. Understanding thermal bridging through timber framing leads to strategies like continuous external insulation, advanced framing techniques, or hybrid systems combining cavity and external insulation. These approaches improve overall thermal performance while addressing moisture management concerns.
Comfortech, for example, has developed a Secondary Insulation Layer Wall Solution, which enables the delivery of a 90mm timber frame wall, with a secondary insulation between 45mm thick internal battens.
Roof and ceiling insulation offers the greatest impact on thermal performance per dollar invested. New Zealand's variable climate requires systems that perform in both heating and cooling modes. Bulk insulation combined with reflective barriers provides year-round benefits, while proper ventilation prevents moisture accumulation that can compromise insulation performance.
Knauf Insulation developed a full range of products to meet the H1 requirements and complement the systems required to achieve efficient, cost effective solutions.
Its single-layer ceiling system, designed for truss roofs, is faster, easier, and cost-effective to use. It provides H1 solutions without requiring any changes to current construction methods. Its skillion roof insulation products provide the thermal values required while acknowledging ventilation and best practice methods of construction.
Moisture management
Foundation waterproofing requires comprehensive approaches that address both liquid water and water vapour. Damp-proof membranes under concrete slabs, drainage systems around foundations, and proper detailing at foundation-to-wall junctions prevent moisture infiltration that can compromise both structural elements and insulation performance.
Insulation and moisture interact in complex ways. Bulk insulation can trap moisture if not properly detailed with vapour barriers and ventilation systems. Understanding where condensation occurs in wall and floor assemblies helps builders detail systems that maintain thermal performance while managing moisture loads.
Ventilation integration becomes particularly important in well-insulated homes. Reduced air leakage improves energy efficiency but requires mechanical ventilation systems to maintain indoor air quality and prevent moisture accumulation. Planning ventilation systems during foundation and framing stages ensures optimal performance and cost-effective installation.
Sustainable materials increasingly feature in foundation and insulation applications. Recycled foam insulation, natural fibre insulation products, and low-carbon concrete alternatives allow builders to reduce environmental impact while maintaining performance standards.
Installation standards are critical, however. Even the best foundation and insulation systems fail if poorly installed. Establishing quality control procedures ensures that designs translate into building performance. This includes proper storage of materials, weather protection during installation, and verification of thermal bridge details.
Thermal imaging can provide valuable quality control tools for insulation installation. Post-installation thermal surveys identify gaps, compression, or thermal bridging that compromise performance.
Regional considerations must be made for New Zealand’s diverse climate zones as these require adapted approaches to foundation and insulation systems. What works in Northland's subtropical conditions may be inappropriate for Canterbury's cooler climate, for example.
Getting these fundamentals right requires understanding, planning, and execution that goes beyond minimum code compliance. To achieve long-term performance, paying extra attention to foundations and insulation can pay dividends, leading to consistent customer satisfaction and building a strong reputation for your work and your business.
