Insulation Upgrades for Older Homes

Victorian and Edwardian properties across North London are beautiful but energy-inefficient. Built before insulation became standard, these solid-walled homes lose significant heat, creating high energy bills and carbon emissions. Strategic insulation upgrades improve comfort, reduce costs, and increase property values while respecting period character. This guide covers practical insulation solutions for older London homes.

Priority Areas for Insulation

Loft Insulation: Highest priority—25-30% heat loss through un insulated roofs. Modern standard: 270mm insulation. Cost: £500-£1,500. Payback: 2-4 years. DIY-friendly with mineral wool rolls.

Solid Wall Insulation: 35% heat loss through uninsulated solid walls. Internal or external insulation options. Cost: £8,000-£18,000 whole house. Significant improvement but expensive.

Floor Insulation: 10-15% heat loss through floors. Insulation between joists reduces loss. Cost: £2,000-£5,000. More disruptive than loft but worthwhile.

Draught-Proofing: 15-20% heat loss through gaps. Most cost-effective upgrade. Professional draught-proofing: £300-£800. Immediate comfort improvement.

Loft Insulation Details

Current building regulations require 270mm thickness (U-value 0.16). Options include:

• Mineral wool rolls: Most economical, DIY-friendly, £300-£700 materials
• Blown-in insulation: Professional installation, fills gaps, £800-£1,200
• Rigid board insulation: For loft conversions with limited height, more expensive

If loft used for storage, board over insulation. Include hatch insulation and pipe lagging.

Solid Wall Insulation Options

Internal Wall Insulation (IWI):

• Insulated plasterboard fixed to external walls
• Reduces room size by 50-100mm
• Cost: £40-£70 per sq m (£8,000-£14,000 typical house)
• No scaffolding needed
• Can do room-by-room
• Doesn't alter external appearance (good for conservation areas)
• Risk of interstitial condensation if poorly designed

External Wall Insulation (EWI):

• Insulation boards fixed to external walls, rendered over
• More effective than IWI (no thermal bridges)
• Cost: £100-£150 per sq m (£15,000-£25,000 typical house)
• Requires scaffolding
• Changes external appearance (rarely permitted in conservation areas)
• Protects original walls from weather
• Must do whole house at once

For period properties in conservation areas, IWI only practical option despite drawbacks.

Floor Insulation

Victorian/Edwardian houses have suspended timber floors. Insulation installed between joists:

• Lift floorboards (can relay originals or replace with new)
• Install netting between joists
• Lay insulation (mineral wool or rigid boards)
• Ensure ventilation below floor maintained (prevent rot)
• Cost: £30-£50 per sq m (£2,000-£4,000 typical ground floor)

Less disruptive in empty properties or during renovation. Significant comfort improvement in cold months.

Window Upgrades

Original single-glazed sash windows lose heat but are character features worth preserving:

Draught-Proofing: Professional brush seals reduce air infiltration by 90%. Cost: £100-£150 per window. Dramatic comfort improvement.

Secondary Glazing: Discreet internal glazing provides near-double-glazing performance without replacing originals. Cost: £200-£400 per window. Excellent acoustic benefits too.

Slim Double-Glazing: Modern units fit existing sash frames. May require planning permission in conservation areas. Cost: £800-£1,200 per window.

For most period properties, draught-proofing plus secondary glazing offers best balance of performance, cost, and heritage preservation.

Avoiding Moisture Problems

Solid-walled period properties were designed to "breathe"—moisture evaporates through permeable materials. Insulation must not trap moisture:

• Use breathable materials (mineral wool, wood fibre boards)
• Avoid impermeable vapour barriers on solid walls
• Maintain ventilation (don't block airbricks)
• Install mechanical ventilation if making building very airtight
• Lime plaster more compatible than gypsum in very old properties

Specialist advice important for listed buildings or properties with historic significance.

Heating System Upgrades

After insulating, heating systems can often be downsized saving money:

• Modern combination boilers more efficient than old systems
• Smart thermostats and zone controls reduce waste
• Thermostatic radiator valves (TRVs) on each radiator
• Heat pumps become viable after good insulation
• Radiator upgrades improve heat distribution

Costs and Savings

Typical Investment:

• Loft insulation: £500-£1,500
• Draught-proofing: £500-£1,200
• Floor insulation: £2,000-£5,000
• Internal wall insulation: £8,000-£14,000
• Window improvements: £3,000-£8,000

Annual Savings: Well-insulated Victorian house can save £800-£1,500/year on heating depending on size and fuel type. Plus improved comfort year-round.

Grants and Funding

Various schemes available:

• ECO4 scheme for low-income households
• Local authority grants (check Camden, Barnet, Haringey, Westminster councils)
• Green Homes Grant (when available)
• 0% VAT on energy-saving materials for some work