Loft Insulation Guide

Your Step-by-Step Loft-Insulation Guide

1. Why Loft Insulation Matters

Loft insulation can significantly reduce heating costs and improve home comfort. According to Which?, installing loft insulation can cut energy bills by up to £340 per year, depending on your home type. Even topping up existing insulation yields savings, even when increasing from 120 mm to 270 mm, savings range from £17 to £30 per year.

The Energy Saving Trust estimates that upgrading from around 120 mm to the recommended 270 mm of insulation can save £20 per year in Great Britain and £25 in Northern Ireland.

2. Understanding Costs & Payback

Cost Estimates:

• For a semi-detached house, professional installation from 0 mm to 270 mm costs around £900, while topping up from 120 mm to 270 mm costs approximately £750.
  
• According to Home Owners Alliance, typical professional installation costs are:
• Mid-terrace: £654
• Semi-detached: £825
• Detached house/bungalow: £1,206
  

Estimated Annual Savings by Property Type:

• Mid-terrace: £200 per year
• Semi-detached: £230
• Detached house: £380
• Detached bungalow: £370
  

Typical payback period:

• Mid-terrace: ~3.3 years
• Semi-detached: ~3.6 years
• Detached houses/bungalows: ~3.2 to 3.3 years
  

3. Should You Do It Yourself or Hire a Pro?

• DIY installation can be significantly cheaper. For example, you can buy a 100 mm-thick roll covering about 8.3 m² for around £20.
• Professional installation may offer better coverage and efficiency, especially for less accessible lofts.

4. Checklist: What to Do and How

1. Inspect existing insulation measure its depth. A depth check (using a ruler) helps assess whether you need a top-up.
   
2. Aim for at least 270 mm of insulation, as recommended by building regulations for new builds.
   
   
3. Check for ventilation and loft conditions:

• Ensure your loft is dry, accessible, and free of condensation or dampness before insulating.
  
• Proper ventilation prevents moisture issues when adding insulation.
  
  

   Install or top up insulation carefully:

• If you need storage space, install insulation between joists and lay rigid boards or raised flooring above, without compressing the insulation layer.
  

5. Extras You Might Want to Know

• Check for Efficiency Clues: A quick test observe your roof on a frosty morning. Patchy frost melting may indicate heat loss through the roof.
  
• Government Support: Eligible households might access funding through the Great British Insulation Scheme (GBIS) especially if the property has a low EPC rating or the homeowner receives certain benefits. Savings may reach £300–400 per year across the UK.
  
• Health & Safety Warning: Some spray-foam installations have caused structural issues in rare cases making properties unmortgageable. Ensure you use reputable methods and installers to avoid such risks.
  

6. Quick Summary Table