Best Insulation for Old Houses
Specialised insulation solutions for heritage homes and houses built before 1980
Heat loss in uninsulated old homes
Higher heating costs vs modern homes
Annual savings with proper insulation
Old House Assessment Tool
Assess Your Old House Insulation Needs
Tell us about your house to get specific recommendations for your era and style
When was your house built?
Era-Specific Insulation Strategies
Pre-1920s Houses: Colonial & Victorian Era
Typical Construction Issues:
- • No insulation anywhere - R-value of 0
- • High ceilings - Large volume to heat
- • Single skin brick walls - Thermal bridging
- • Timber floors on high piles - Cold underfloor
- • Single glazed sash windows - Major heat loss
- • Large gaps and air leaks - Settlement over time
Prioritised Solutions:
- • Priority 1: R3.6+ ceiling insulation (bulk or batts)
- • Priority 2: Underfloor insulation (R1.8-2.5)
- • Priority 3: Comprehensive air sealing
- • Priority 4: Heavy thermal curtains
- • Consider: Internal wall lining with insulation
- • Heating: High-efficiency wood burner or heat pump
1920s-1940s Houses: Bungalows & Inter-war Homes
Common Features & Issues:
- • Weatherboard with timber frame - No wall insulation
- • Suspended timber floors - Often no underfloor insulation
- • Fibrolite or plaster ceilings - Little to no ceiling insulation
- • Casement windows - Better than sash but still single glazed
- • Galvanised iron roofs - Good for insulation installation
Recommended Approach:
- • Ceiling: R3.2+ bulk insulation (easy access)
- • Underfloor: R1.8+ polyester batts
- • Walls: Retrofit wall insulation where possible
- • Air sealing: Focus on window/door frames
- • Windows: Retrofit double glazing or thermal curtains
1940s-1960s Houses: State Houses & Post-war Homes
Construction Characteristics:
- • Standardised designs - Consistent construction methods
- • Concrete slab floors (later builds) - Thermal bridging
- • Minimal ceiling insulation - R1.0 or less
- • No wall insulation - Cavity walls but unfilled
- • Aluminium windows (1950s+) - Conductive frames
Upgrade Strategy:
- • Ceiling: Upgrade to R3.2+ (remove old insulation first)
- • Walls: Cavity fill insulation where possible
- • Floors: Carpet/rugs over concrete, underfloor for suspended
- • Windows: Consider double glazing retrofit
- • Air tightness: Seal electrical penetrations
1960s-1980s Houses: Mid-century & Early Modern
Design Features:
- • Open plan designs - Large spaces to heat
- • Flat or low-pitch roofs - Limited ceiling space
- • Large windows - Significant glazing areas
- • Concrete construction - Thermal mass but cold surfaces
- • Some basic insulation - But below modern standards
Improvement Focus:
- • Ceiling: Top-up to R3.2+ (work around limited height)
- • Walls: External insulation systems where possible
- • Windows: Double glazing essential for large areas
- • Thermal mass: Use concrete thermal mass effectively
- • Zoning: Heat only occupied areas
Special Considerations for Old Houses
Heritage & Character Protection
External Appearance
Most insulation improvements are internal and won't affect the historic character of your home's exterior.
Council Requirements
Check if your home has heritage protection. Some councils offer specific guidance for upgrading heritage homes.
Professional Advice
Consult heritage architects or conservation specialists for listed buildings or significant heritage homes.
Moisture Management
Ventilation Balance
Old houses often rely on natural ventilation. Ensure adequate ventilation when improving air tightness.
Vapour Barriers
Retrofit insulation must consider existing moisture patterns. Avoid trapping moisture in walls.
Building Fabric
Old timber needs to breathe. Use vapour-permeable materials where appropriate.
Best Materials for Old Houses
| Insulation Type | Best For | R-Value | Cost/m² | Heritage Suitability |
|---|---|---|---|---|
| Polyester Batts Non-combustible, stable | Ceiling & underfloor in heritage homes | R1.8-R3.6 | $12-18 | Excellent |
| Glasswool Batts Cost-effective option | Ceiling spaces with good access | R1.5-R3.6 | $8-14 | Good |
| Bulk Fill Blown-in installation | Irregular ceiling spaces, tight areas | R2.2-R4.0 | $10-16 | Excellent |
| Rigid Foam Boards High R-value, space-efficient | Limited ceiling height situations | R2.0-R6.0 | $15-30 | Moderate |
| Natural Fiber Sheep wool, recycled materials | Heritage homes wanting natural materials | R1.8-R3.2 | $18-35 | Excellent |
Old House Retrofit Challenges & Solutions
Challenge: Limited Ceiling Access
Common Issues:
- • Low roof pitch limiting headroom
- • No ceiling hatch or manhole
- • Decorative plaster ceilings
- • Electrical wiring in the way
Solutions:
- • Blown-in bulk insulation through small holes
- • Create new access point in wardrobe
- • Professional installers with specialized equipment
- • Rigid board insulation in tight spaces
Challenge: Wall Insulation in Solid Construction
Issues with Brick/Stone Walls:
- • No wall cavities to fill
- • External insulation changes appearance
- • Internal insulation reduces room size
- • Risk of moisture trapping
Practical Approaches:
- • Focus on ceiling insulation (biggest impact)
- • Internal wall lining with insulation
- • Insulated plasterboard systems
- • Thermal mass strategies
Challenge: Asbestos in Older Homes
Potential Asbestos Locations:
- • Ceiling tiles and boards (pre-1980s)
- • Pipe lagging and hot water cylinder wrapping
- • Some old insulation materials
- • Fibrolite wall and ceiling sheets
Safe Management:
- • Professional asbestos assessment first
- • Don't disturb suspected asbestos materials
- • Install insulation over/around existing materials
- • Use certified asbestos removal contractors if needed
Challenge: Electrical & Services Integration
Old House Electrical Issues:
- • Old wiring may need upgrading
- • Junction boxes in ceiling spaces
- • Lack of adequate earthing
- • Non-standard electrical installations
Safe Integration:
- • Electrical inspection before insulation work
- • Coordinate with licensed electrician
- • Use insulation suitable around electrical services
- • Maintain safe clearances from heat sources
Cost-Benefit Analysis for Old Houses
High Impact Upgrades
Medium-Term Investments
Old House Investment Strategy
- Start with ceiling insulation - Biggest impact for lowest cost
- Add comprehensive air sealing - Amplifies insulation effectiveness
- Install efficient heating after insulation - Right-size based on reduced heat loss
- Consider staged improvements - Use annual savings to fund next upgrade
- Maintain heritage character - Most improvements are internal and invisible
Frequently Asked Questions
Is it worth insulating a very old house?
Absolutely. Old houses often have the most to gain from insulation upgrades. A house with no ceiling insulation can see 40-60% reduction in heating costs after proper insulation installation. The older the house, the greater the potential savings.
Will insulating my heritage home damage its historic value?
Most insulation improvements are internal and won't affect the external heritage character. Ceiling and underfloor insulation, air sealing, and internal upgrades can dramatically improve comfort while preserving historic appearance. Consult heritage advisors for listed buildings.
What's the best insulation for a house with no ceiling access?
Blown-in bulk insulation is ideal for houses with limited or no ceiling access. It can be installed through small holes drilled in the ceiling, then patched and painted. This method allows good coverage even in tight spaces without major disruption.
How do I handle potential asbestos in my old house?
Have a professional asbestos assessment before any insulation work in houses built before 1980. Often insulation can be installed without disturbing existing materials. If removal is needed, use certified contractors. Don't attempt DIY removal of suspected asbestos.
Can government grants be used for heritage home insulation?
Yes, the Warmer Kiwi Homes programme applies to all eligible homes regardless of age. Heritage homes often qualify for the full $1,300 grant as they typically have little or no existing insulation. Some councils offer additional heritage-specific grants.
Should I DIY insulation in an old house?
Professional installation is recommended for old houses due to potential complications like asbestos, irregular construction, electrical issues, and heritage considerations. Professionals have experience with these challenges and can ensure safe, effective installation.
Transform Your Heritage Home
Get specialised assessment and solutions for old house insulation challenges