Improving insulation can make a home warmer, reduce heat loss and lower the amount of energy needed for heating.

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But there is no single insulation solution that is right for every property.

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A modern cavity-wall house, a Victorian terrace, a converted flat and a solid-wall period property can require very different approaches.

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Before committing to expensive insulation work, it is worth understanding where your home is actually losing heat, which parts of the building can practically be improved and which measures should take priority.

Where Does a Home Lose Heat?

 

Heat can escape through several parts of the building, including:

• roofs and lofts

• external walls

• suspended or solid floors

• windows and doors

• poorly insulated extensions

• gaps and uncontrolled air leakage

• junctions between walls, floors and roofs

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The proportion lost through each element varies from one property to another.

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That means the most obvious improvement is not always the one that offers the greatest benefit.

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Loft and Roof Insulation

 

Loft insulation is often one of the simplest and most cost-effective improvements available.

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If the loft is accessible and existing insulation is limited, increasing the insulation can significantly reduce heat loss through the roof.

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However, there are still details to consider.

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Insulation should not block necessary ventilation, and attention may be needed around:

• eaves

• tanks and pipework

• loft hatches

• recessed lighting

• converted loft spaces

• sloping ceilings

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Where the loft has already been converted, improving insulation can be more complicated because much of the roof construction may already be concealed.

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Cavity Wall Insulation

 

Many homes built with cavity walls may be suitable for cavity-wall insulation.

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Where appropriate, filling an uninsulated cavity can improve thermal performance without significantly changing the appearance or internal dimensions of the property.

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But not every cavity wall should automatically be filled.

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The property's age, exposure, wall condition and existing construction should all be considered before work is carried out.

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Solid Wall Insulation

 

Solid-wall properties require a very different approach.

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Many Victorian, Edwardian and other older homes were constructed without a cavity between the internal and external faces of the wall.

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Improving these walls usually means considering either:

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internal wall insulation

or

external wall insulation.

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Both can reduce heat loss considerably, but both have advantages and disadvantages.

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Internal Wall Insulation

 

Internal wall insulation involves adding insulation to the inside face of external walls.

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It can be an attractive option where the external appearance of the building needs to remain unchanged.

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However, it can affect:

• room dimensions

• skirting and cornices

• sockets and radiators

• window reveals

• floor and ceiling junctions

• kitchens and fitted furniture

• moisture movement through the wall

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It can also create thermal bridges if junctions are not properly detailed.

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For this reason, internal wall insulation should be treated as a building-design decision rather than simply another decorative layer.

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External Wall Insulation

 

External wall insulation places insulation on the outside of the building and normally includes a new rendered or clad finish.

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This has the advantage of wrapping more of the building in a continuous layer of insulation and can reduce some of the thermal bridging associated with internal systems.

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However, it can be more expensive and may affect:

• the appearance of the property

• roof and eaves details

• window and door reveals

• drainage pipes

• boundaries

• planning requirements

• architectural features

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It may therefore be inappropriate for some period properties or conservation settings.

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What About Victorian and Period Homes?

 

Older homes require particular care.

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Traditional buildings often behave differently from modern construction, particularly in the way they manage moisture.

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Installing insulation without considering ventilation, damp, condensation and the existing wall construction can create problems.

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For example, making a property substantially more airtight while ignoring ventilation may improve one aspect of energy performance while causing another problem elsewhere.

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The objective should be to make the home warmer and more efficient without damaging the building or creating unhealthy internal conditions.

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Floor Insulation

 

Floors can also contribute to heat loss and draughts.

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Suspended timber floors may sometimes be insulated between the joists, while solid floors can require a very different approach.

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Floor insulation may be particularly worth considering where major refurbishment work is already planned.

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However, lifting floors simply to install insulation can involve considerable disruption, so the likely benefit should be weighed against the cost and extent of the work.

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Should You Replace the Windows as Well?

 

Insulation and glazing are often considered together.

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Older windows can contribute to heat loss and draughts, but replacing all the windows in a property can represent a major investment.

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In some homes, improving the walls, roof or heating controls may offer better value before replacing otherwise serviceable glazing.

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This is why it makes sense to compare improvements rather than viewing each one in isolation.

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Insulation and Ventilation Need to Work Together

 

As homes become better insulated and more airtight, controlled ventilation becomes increasingly important.

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Without adequate ventilation, moisture generated by cooking, washing, bathing and everyday occupation can accumulate inside the property.

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This can contribute to:

• condensation

• mould

• poor indoor air quality

• excessive humidity

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Depending on the level of improvement being undertaken, ventilation options may include upgraded extract fans, continuous mechanical ventilation or MVHR.

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Insulation should therefore form part of a whole-home strategy, not simply a standalone product purchase.

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Could Better Insulation Reduce the Size of Your Heating System?

 

Yes.

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Reducing heat loss means the property requires less energy to maintain a comfortable temperature.

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This can affect decisions about:

• boiler replacement

• radiator sizes

• underfloor heating

• heat pumps

• future heating costs

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If you are considering both insulation and a new heating system, it may make sense to establish the insulation strategy first.

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Otherwise, you could design a heating system around a level of heat loss that will later change.

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Grants and Financial Support May Help With the Cost

 

Insulation can involve substantial expenditure, particularly where solid walls, floors or extensive refurbishment are involved.

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Depending on the property, household and schemes available at the time, grants or other financial support may be available towards some energy-efficiency improvements.

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That is worth investigating before accepting quotations or deciding which measure to undertake.

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As part of a Green Home Assessment, APN Green Homes considers the current grants, incentives and support relevant to the improvements being recommended for your property.

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Knowing what financial assistance may be available can influence both the scope and timing of the work.

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Do Not Let the Contractor Decide the Whole Strategy

 

Different contractors naturally specialise in different products.

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An external-wall insulation company will recommend external wall insulation.

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An internal-wall insulation contractor will naturally discuss internal systems.

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A window company will recommend windows.

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A heating company will focus on heating.

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APN Green Homes takes a different approach.

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We do not start with the product. We start with the property.

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The objective is to establish which improvements are appropriate, how they interact and where your money may be best spent.

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Find Out What Should Come First

Before committing to insulation work, it is worth understanding:

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• Where is my home losing the most heat?

• Should I start with the loft, walls or floors?

• Is internal or external wall insulation more appropriate?

• Could insulation create condensation or ventilation problems?

• Should I insulate before replacing the heating system?

• Would new windows give better or worse value?

• What grants or incentives may help with the cost?

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Get Independent Whole-Home Advice

 

APN Green Homes provides independent Green Home Assessments for homeowners considering energy-efficiency improvements.

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Your personalised report can consider:

• loft and roof insulation

• cavity walls

• internal wall insulation

• external wall insulation

• floor insulation

• windows and glazing

• heating

• ventilation

• heat pumps

• solar and battery storage

• grants and incentives

• priorities for future improvements

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The aim is simple:

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to help you understand which insulation improvements are appropriate for your home, what should come first, and what financial support may be available before you commit.

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Green Home Assessment — £495 + VAT

 

Get the plan before you start spending.