The Ultimate Guide to Insulation


If you are a homeowner looking to reduce your energy bills, improve comfort, and make your home environmentally friendly, then this guide is the resource for you. This guide will provide you with the knowledge and tools you need to insulate your home effectively.

To create an energy-efficient home it is important that proper insulation is installed, to make sure that heat loss is significantly reduced during cold winter months, and that heat gain is significantly reduced in hot summer months.

In this guide we will cover a range of topics including the different types of insulation, how to install it and how to keep it maintained. Whilst also helping you find ways to save money and lower your carbon footprint.

Browse the guide at your own pace or open the dropdown menu to click the links to jump to the sections you need the most.

Section 1 – Importance of Home Insulation

Insulating your home can provide a comfortable, energy-efficient, and sustainable living environment. It is essential that homeowners insulate their homes, as it can offer a wide range of benefits including:

Improved Energy Efficiency: Effectively insulating your home will reduce heat transfer, preventing warm air from escaping in the winter and keeping cool air in during the summer. The insulation barrier helps to maintain a comfortable temperature indoors and reduces the reliance on traditional heating and cooling systems, increasing energy efficiency.

Reduced Energy Bills: Insulating your home will help to significantly lower energy costs as a well-insulated home requires less energy to maintain a comfortable temperature. Making insulating your home a wise long-term investment.

Enhanced Comfort: It will minimise draughts, cold spots, and temperature fluctuations, creating a more comfortable living environment. Insulation can also decrease noise transmission, making a quieter indoor atmosphere.

Environmental Impact: Through insulating your home, you can reduce your energy consumption, which will also lower your carbon emissions. Therefore, choosing to insulate your home will help to contribute to a greener and more sustainable future.

Increased Property Value: When it comes to property value, insulation is a valuable asset to have. Potential buyers tend to look for homes that are insulated properly, as it provides comfort, potential energy cost savings, and a lower environmental impact.

Condensation Control: By creating a thermal barrier, insulation can help reduce condensation. Condensation can cause a range of issues including mould, mildew, and damage to property. Insulation minimises these risks, which will overall protect your home and create a healthy living environment.

Section 2 – Types of Insulation

If you choose to insulate your home, it is important to understand that there are different types of insulation materials. Each of these materials has its own properties, advantages, and recommended applications. The most common materials are:

Fibreglass: This material is affordable, readily available, fire-resistant, and easy to install. It is made from fine glass fibres that traps air to create a thermal barrier. Fibre glass also significantly reduces the growth of both mildew and mould. This material is recommended to be installed in lofts/attics, walls, and floors. When installing it is important to wear protective clothing as it can cause skin irritation.

Cellulose: This material is made from recycled paper that has been treated to be fire-resistant. This type of insulation has excellent soundproofing qualities and creates a good thermal barrier. Many homeowners are choosing this material as it is a more sustainable option. It can be either blown or densely packed into loft/attic space, walls, and hard to reach areas. If choosing this insulation type it is recommended that you hire a professional.

Spray Foam: Spray foam expands to fill gaps, meaning it has excellent sealing properties that creates an effective thermal barrier and prevents condensation issues. In many cases this material can also increase structural rigidity. Spray foam can be used to seal gaps in wall cavities and in the loft/attic. Often this type of insulation is a more expensive choice.

Rigid Foam: This material provides a significant thermal barrier and protects against moisture. This type of insulation can be used both outside and inside of the home and can provide good insulation in areas of limited space. Usually it is used in foundations, exterior walls, and under-slab applications. Commonly this type of insulation is a more expensive choice.

Reflective: This insulation type uses reflective material, such as aluminium foil, to reflect heat away from the living space. It is lightweight and is easy to install, combined with other insulation materials it can enhance effectiveness. It is important to note that reflective insulation should not be used as insulation alone and must be combined with another insulating material.

When choosing the right insulation for you, consider factors such as the climate, building structure and your budget. To determine the right material for you, consult a professional.

Section 3 – Areas for Insulation

Walls: Insulating walls will help to prevent both heat loss and gain, increasing the buildings energy efficiency. Consider the wall type (e.g., exterior, interior, load bearing, partition, or masonry), local building regulations, and the desired U-value. Walls can be insulated through cavity wall insulation (filling the gaps with insulation material) or adding insulation to the exterior or interior of the wall.

Roofs: Adding roof insulation to your home will minimise heat transfer and prevent ice dams from occurring. Consider the roof type (e.g., gable, flat, arched, or hipped), the climate conditions, and ventilation requirements. Roofs can be insulated between the rafters, by adding insulation boards above the roof deck, or by using spray foam for sealing.

Floors: Insulating your floors can prevent heat loss or gain between the different levels of your home. Consider the floor type (e.g., over a heated area, carpeted or uncarpeted) and local building regulations. Insulation can be placed between floor joists, installed on the underside of the floor, or on the subfloor.

Lofts/Attics: Insulating loft space is important as heat rises and can be lost. Consider the desired U-level, air sealing, and the ventilation requirements. Insulation can be blown in or can be densely packed between loft joists. Insulating around hatches and vents can also reduce heat loss and gain.

Basements/Cellars: Insulating cellars can prevent heat loss and reduce issues caused by moisture, by helping to control humidity. Insulate the cellar walls or floors and seal any gaps or cracks.

Doors and Windows: These tend to have their own insulating properties although their efficiency can be increased. Consider seals, weatherstripping, and double glazing. Draught stoppers, door sweeps, curtains and blinds are also effective.

Section 4 – Insulation U-Value

In the UK, the thermal performance of a building element is shown through its U-value. This shows the amount of heat loss per square metre per degree (Celsius) temperature difference.

The UK’s Building Regulations set the minimum U-value for different parts of a building, including the walls, roofs, floors, windows, and doors. The requirements are based on the construction type, specific location within the UK, the region’s climate, energy efficiency standards, and building regulations. Achieving higher U-values than the minimum requirement can result in better energy efficiency and thermal performance.

When considering insulation, it is recommended that you consult the Building Regulations, local building authorities, or a professional for the specific U-value requirements and recommendations.

Section 5 – Insulation Techniques

Air Sealing: Seal gaps, cracks, or openings before insulating to prevent air leakages. Use caulk or weatherstripping around windows or doors. Pay attention to junctions between different building materials.

Vapour Barriers: Vapour barriers are essential in areas with colder climates to control moisture and prevent condensation. They should be installed on the warmer side of the insulation to prevent moisture reaching the colder side. Make sure sealing is done properly and overlap if necessary.

Ventilation Considerations: Ventilation is important to maintain indoor air quality and control the levels of moisture. Install ventilation systems to ensure fresh air is circulated whilst retaining heat.

Avoiding Common Mistakes: Compressing insulation materials can reduce their effectiveness. Make sure cavities are filled properly to eliminate gaps or breaks in the thermal barrier. Always follow the manufacturer’s guidelines.

Loft Insulation: Ensure consistent coverage, lay insulation between and over ceiling joists to ensure optimal thermal performance. The recommended thickness for loft insulation is around 270mm thick. To maintain insulation avoid compressing the material used around the eaves.

Wall Insulation: Hire a professional to inject insulation into cavity walls. For a continuous insulation layer, obstructions must be properly cleared. For solid walls, consider exterior or interior insulation. For guidance seek expert advice.

Floor Insulation: Insulate floors that are above unheated spaces. Install the insulation material between floor joists and ensure proper coverage. For solid floors use insulation boards or rigid foam insulation.

Windows and Doors: Use draught proofing strips to increase energy efficiency, alternatively you can also apply sealant or weatherstripping, and install double or triple glazing. To reduce heat loss further consider insulated or thermal curtains.

Professional Assistance: Seek advice from a certified insulation professional or energy assessor if you are unsure about your insulation needs. They can provide tailored recommendations and can ensure that you are complying with the building regulations.

Section 6 – Energy Audit

Conducting an energy audit is a valuable way to improve your home’s energy efficiency, as it can identify areas of heat loss. An audit can help to pinpoint areas within your home that is losing heat, such as through poorly insulated walls, roofs, or windows. By addressing these areas and improving their insulation properties you can increase your homes energy efficiency and reduce your heating costs.

Energy audits can also help you to detect if there are any air leakages within your home, such as through cracks, gaps, and openings. Identifying and sealing these areas will help to prevent drafts and heat loss. Which will ultimately lower your heat consumption.

Once you have completed an energy audit you will be able to prioritise any upgrades that need carrying out, based on their potential impact and cost effectiveness, as well as making informed decisions.

To carry out an audit you must:

  • Carry out a visual inspection, such as looking for leaks (draughts, gaps, cracks) around windows, doors, or electrical outlets. Check the insulation levels in the loft/attic, walls, and floors.
  • Use a thermal imaging camera or a smartphone app to detect temperature differences. This will help to identify areas of heat loss.
  • Hire a professional to carry out an air leakage test. To do this negative pressure needs to be created to identify air leaks.
  • Evaluate how efficient your appliances, lighting, and heating/cooling systems are. You may need to consider upgrading to more energy efficient models.
  • Ensure that you review your energy bills to identify areas of high consumption.

It is recommended that you hire a professional to carry out your energy audit. This is because they can provide a comprehensive assessment using suitable equipment alongside their expertise. Inspections will be carried out thoroughly, in order to find the precise areas within your home that are causing air leaks and heat loss.

When looking for a professional, make sure that they are certified or affiliated with a recognised efficiency programme or organisation. Once they have caried out their audit they should supply you with a detailed report, with recommendations and guidance tailored to improving your home’s energy efficiency.

Section 7 – Insulation Cost and Budgeting

Insulation Costs

Material Costs: The price of the materials will vary depending on its type and quality. Fibreglass, cellulose, spray foam, and rigid foam tend to be the cheaper options, although this depends on the quality, amount, and thickness.

Installation Costs: Hiring a professional to install the insulation comes with additional costs. Prices can vary depending on the size, material type and complexity of the installation process. One of the most important aspects of hiring a reputable professional installer is that the job will be done correctly.

Potential Savings: In the long-term, insulation can provide significant energy savings, as it will reduce heating and cooling costs. The amount of savings will depend on the quality of the material, the size of your home, and your energy consumption patterns.

Budgeting Strategies and Cost-Effective Options

Prioritise: Identify areas of your home that will benefit the most from insulation. Ensure that you focus on areas that suffer from significant heat loss first, such as the roof, walls, and windows.

Research: Research the different insulation types, their costs and thermal performance before making a decision. Compare prices and consider their long-term benefits.

Grants and Incentives: Research grants, incentives, or government schemes that could help to offset the costs of insulation installation.

Professional Installation: A DIY installation may be the cheaper option, however, many of the insulation materials require extra research, specific safety measures, or complex installation processes. It is recommended that a professional is hired, as they will already have the knowledge, skills, and experience required. A professional installer will work efficiently, reducing the disruption to your daily life. Reputable insulation contractors may also provide warranties and guarantees.

Long-Term Perspective: Consider insulation as a long-term investment. Although upfront costs can be significant, the energy savings over time can lower energy costs in the future offsetting the initial expenses.

Section 8 – Insulation for Different Home Types

Older or Historic Houses

Preservation: When insulating an older house, preservation and energy efficiency must be considered. Ensure that any insulation installed will not damage the original structure.

Breathability: Many older houses have construction materials (e.g., lime-based plaster) that need breathability. To prevent dampness and to maintain the building’s integrity, opt for a material that allows moisture to pass through.

Heritage Regulations: Consult with a professional or local authorities to ensure you are complying with preservation or conservation regulations.

New Constructions

Building Regulations: New constructions must comply with the current building regulations; this includes the insulation requirements. Requirements are set for walls, roofs, floors, and windows.

Continuous Insulation: To minimise any gaps within the thermal barrier and to increase energy efficiency make sure that the insulation is installed as a continuous envelope. This includes walls, roofs, and floors without gaps.

Modular Homes

Factory-Installed Insulation: Many modular homes have pre-installed insulation. Make sure you check its quality and adequacy, and if any additional insulation is required, such as in joints, corners, or roof connections.

Air Sealing: During the assembly of the house, it is important that proper air sealing is carried out. When moving into a modular house, pay attention to areas where a leak may occur such as windows, doors and near electrical structures.

Multi-Storey Buildings

Acoustic Insulation: Both thermal and acoustic insulation needs to be considered. Insulating walls and floors between rooms and units can reduce noise transmission, as well as minimising heat loss/gain.

Fire Safety: Insulation must meet fire safety regulations if being installed in multi-storey buildings. Check the insulation’s fire rating and ensure compliance to standards of safety for occupants.

Section 9 – Insulation and Building Codes

Building Codes and Regulations

Building Regulations: The UK’s Building Regulations set the minimum standards for insulation for renovations and in new constructions. The UK Government provides specific guidance on thermal performance requirements, including the U-values for walls, floors, roofs, and windows.

Certifications and Standards

  • British Board of Agrément (BBA): This certification verifies the quality, compliance, and performance of insulation materials and products. This provides assurance to the builder, regulator, and the homeowner.
  • Energy Performance Certificate (EPC): This certification rate is mandatory if you are selling or renting a property in the UK. It rates the building’s energy efficiency and provides recommendations for upgrading and improving insulation and reducing energy consumption.

Government, Local Authorities and Energy Suppliers

The UK Government, local authorities and energy suppliers may offer incentives, rebates, or grants to give homeowners financial support towards making energy efficient upgrades. These programs and schemes can vary by region, so it is advised that you check which of these are available for you.

Tax Credits

Landlord Energy Saving Allowance: This tax allows landlords to claim back expenses that are related to energy efficient improvements. This includes insulation upgrades. For more information landlords should consult HM Revenue and Customs (HMRC).

Section 10 – Maintenance and Upkeep

Regular Inspection

  • Periodic visual inspections should be conducted to check the insulation in accessible areas, such as in lofts and cellars. Check for damage, including tears, pest infestations, and compression.
  • Check the moisture levels that can compromise the effectiveness of the insulation, including water stains, mould growth, or dampness.

Addressing Damage or Wear

  • Promptly repair or replace any insulation that is damaged. Patching materials are available for minor tears or compressions. To restore the integrity of the insulation you can add additional insulation.
  • Check the insulation around pipes, ducts, and electrical outlets. These areas can be prone to damage or displacement.

Moisture Management

  • Any identified sources of moisture need to be addressed as they can degrade the performance of the insulation and cause mould growth. Plumbing leaks need to be fixed promptly and dehumidifiers can be used in damp areas.
  • To prevent moisture from entering the insulation layer, make sure vapour barrier techniques are in place.

Settling and Compression

  • Reposition or fluff up loose fill insulation to stop the reduction of effectiveness.
  • Make sure and check that rigid foam or batt insulation hasn’t sagged or shifted, especially in walls.

Air Sealing

  • The efficiency of insulation increases when it is combined with proper air sealing. Regularly check for gaps, cracks, or draughts around windows, doors, or electrical outlets. Use weatherstripping, caulk or sealant to address air leaks.

Professional Insulation Assessment

  • You can hire a professional insulation contractor to assess your insulation, especially for hard-to-reach areas. They will be able to tell you if there are any problems.
  • Professionals can also use thermal image and other techniques to identify issues, assess thermal performance, and recommend solutions.