How to Insulate a House: Tips for Better Efficiency

In summary

• Loft insulation offers the quickest return on investment, reducing heat loss by up to 25% with proper installation of 270mm mineral wool or fibreglass insulation between floor joists

• Wall insulation methods vary significantly between cavity walls in newer properties and solid walls in older homes, with cavity wall insulation costing £500-800 compared to £8,000-15,000 for external solid wall insulation

• Floor insulation prevents heat loss through suspended timber floors and concrete slabs, with rigid foam boards and spray foam providing effective solutions for crawl spaces and problem areas

• Proper vapour barrier installation and air sealing are critical across all insulation types to prevent moisture problems and maintain long-term performance

• Combining comprehensive insulation with thermally efficient windows and doors creates a complete building envelope that maximises energy efficiency and reduces heating bills

  
  

Proper home insulation is fundamental to reducing energy bills and creating comfortable living spaces. With energy costs continuing to rise, understanding how to insulate a house effectively has become essential knowledge for both homeowners and trade professionals.

The right insulation strategy can reduce heat loss by up to 60% (according to Energy Saving Trust), making it one of the most cost-effective improvements you can make to any property.

At True Window & Glass Centre, we've worked across Lincolnshire for over 40 years, helping both domestic and commercial clients improve their properties' energy efficiency.

Through our experience with more than 2,000 satisfied customers, we understand that effective insulation works hand-in-hand with quality glazing solutions.

How to insulate a house

Effective house insulation focuses on three key areas: loft, walls and floors.

Each type of insulation addresses specific heat loss patterns and requires different approaches, materials and installation techniques.

Understanding building codes and proper construction methods ensures your insulation performs optimally for decades.

Loft insulation

Loft insulation delivers the highest return on investment because warm air naturally rises, making your roof space the primary area for heat loss.

Proper attic insulation can reduce overall heat loss by 25%.

Expected costs:

• Blanket insulation (mineral wool/fibreglass): £200-400 for average home

• Loose fill materials: £300-500 including professional installation

• Spray foam: £800-1,200 for complete coverage

  
  

Expected energy savings: Annual savings of £200-300 on heating bills, with payback period typically under two years.

Installation methods

Step-by-step guide:

1. Clear the loft space and check for existing insulation

2. Seal air leaks around light fittings and pipe penetrations

3. Install vapour barrier on the warm side if required

4. Lay first layer between floor joists

5. Add second layer perpendicular to joists, achieving 270mm total depth

6. Ensure no gaps around pipes or in corners

   
   

Common mistakes to avoid

• Compressing insulation reduces its effectiveness significantly

• Blocking ventilation paths causes moisture problems

• Insufficient depth fails building regulations requirements

• Missing vapour barriers in heated spaces create condensation issues

  
  

Wall insulation

Wall insulation methods depend entirely on your property's construction. Wall cavities in properties built after 1920 offer straightforward solutions, while solid walls in older homes require more complex approaches.

Expected costs:

• Cavity wall insulation: £500-800 for typical home

• Internal solid wall insulation: £5,000-8,000

• External solid wall insulation: £8,000-15,000

  
  

Expected energy savings: Wall insulation typically reduces heat loss by 35%, saving £150-250 annually on energy bills.

Installation methods

Cavity walls:

1. Drill small holes in exterior walls at regular intervals

2. Insert insulation material using specialist equipment

3. Seal holes with matching mortar or render

4. Check for thermal bridging around structural elements

   
   

Solid walls: Internal insulation involves fixing rigid foam boards or constructing stud walls with batt insulation, finished with plasterboard. External insulation requires specialist contractors to apply insulation boards with protective render systems.

Common mistakes to avoid

• Poor air sealing around door frames and window reveals

• Inadequate moisture barriers causing damp issues

• Thermal bridging through wall studs reduces efficiency

• Insufficient thickness fails to meet building codes

Floor insulation

Floor insulation prevents cold draughts and heat loss through suspended timber floors and solid concrete slabs. This often-overlooked area can account for 10% of total heat loss.

Expected costs:

• Suspended floor insulation: £400-800

• Solid floor insulation: £1,000-2,000 (if undertaken during renovation)

Expected energy savings: Properly insulated floors save £50-100 annually while significantly improving comfort levels.

What's the most effective floor insulation material?

Rigid foam boards offer superior performance in most situations, providing excellent thermal properties whilst resisting moisture when in direct contact with concrete floors or foundation walls.

Installation methods

Suspended floors:

1. Access from below or lift floorboards

2. Install breathable membrane to prevent draughts

3. Fix rigid foam or mineral wool between floor joists

4. Ensure 50mm ventilation gap below insulation

5. Replace floorboards ensuring no thermal bridging

Solid floors: Installation during construction or major renovation involves laying rigid foam directly onto concrete slabs with protective membrane systems.

Common mistakes to avoid

• Blocking underfloor ventilation causes timber rot

• Missing insulation around edges creates cold bridges

• Inadequate vapour control leads to moisture problems

• Poor sealing around pipe penetrations reduces effectiveness

Other ways to improve comfort and cut energy costs

While comprehensive insulation forms the foundation of energy efficiency, addressing your building envelope holistically maximises performance and comfort.

Thermally efficient windows

High-performance glazing significantly reduces heat gain in summer and heat loss in winter. Our double and triple glazing options feature advanced thermal breaks and low-emissivity coatings that work alongside proper insulation.

Modern uPVC and aluminium windows with multi-chamber profiles minimise thermal bridging. Our slimline heritage units prove particularly effective in older homes where planning restrictions apply.

Thermally efficient doors

Quality doors eliminate draughts whilst providing security and aesthetic appeal. Our composite doors feature insulated cores that prevent thermal bridging, while our aluminium bi-fold and French doors incorporate thermal breaks.

Proper installation includes comprehensive sealing systems around door frames, preventing the air leaks that undermine even the best insulation systems.

Verdict

Effective house insulation requires a systematic approach focusing on loft, wall and floor areas.

Combined with thermally efficient windows and doors, comprehensive insulation creates comfortable, energy-efficient homes that significantly reduce heating costs.

Success depends on selecting appropriate materials, following proper installation techniques and maintaining effective air sealing throughout the building envelope.

Who are TWG?

At True Window & Glass Centre, we've provided glazing services and repairs across Lincolnshire for over 40 years. Based in Lincoln, our FENSA and GGF-accredited team serves domestic and commercial clients throughout Lincoln, Gainsborough, Newark, Grantham, Sleaford and surrounding areas.

We manufacture double-glazed units at our Lincoln headquarters, offering comprehensive window and door solutions including uPVC, aluminium and composite materials. Our product range includes casement, flush sash, tilt & turn and slimline windows in double and triple glazing configurations.

Beyond standard installations, we provide 24/7 emergency glazing services, conservatories, orangeries and bespoke glass solutions. Our trade counter supplies fellow professionals with quality units and sundries.

Contact us on 01522 500892 for expert advice on improving your property's thermal efficiency through quality glazing solutions.

Frequently asked questions

Q: Which areas of your home should you insulate first? A: Start with loft insulation as it offers the quickest payback, followed by cavity walls if applicable, then floors. This prioritisation maximises early energy savings whilst building towards comprehensive coverage.

Q: Can you over-insulate a house? A: While more insulation generally improves efficiency, balance is key. Excessive insulation without proper ventilation creates moisture problems, whilst ignoring air leaks wastes investment in insulation materials.

Q: How long does house insulation last? A: Quality mineral wool and rigid foam insulation typically lasts 40-50 years with minimal maintenance. Spray foam systems often provide similar longevity when properly installed with appropriate vapour barriers.

Q: What's the best approach for basement walls and cathedral ceilings? A: Basement walls require spray foam insulation or foam board insulation with proper vapour barrier installation to prevent moisture issues. Cathedral ceilings need adequate insulation depth with air barrier systems to maintain proper ventilation in these challenging spaces.

Q: Do different types of walls affect cooling bills significantly? A: Yes, exterior insulation and proper air leakage control can reduce cooling bills by 20-40%. Plaster walls in older properties often lack adequate insulation, making retrofit solutions essential for year-round energy efficiency in both heating and cooling seasons.