Non-traditional housing is any house not built of brick or stone with a slate or tiled roof. These homes have unique structural characteristics that present distinct challenges when it comes to insulation. There are around 1.5 million non-standard construction homes in the UK, many of which were built in response to the housing shortages after the First and Second World Wars.

Following these global conflicts, the government was pressured to build homes quickly to accommodate the growing population despite the lack of skilled labour and limited available materials. This led to new construction methods, with the Building Research Establishment (BRE) documenting over 500 different systems between 1919 and 1976. These innovative techniques primarily aimed to provide permanent or long-term housing, although some were initially intended as emergency or temporary solutions.

In the 1980s, the BRE conducted condition surveys on non-standard construction homes, revealing that several concrete housing systems had fundamental structural issues. As a result, many of these homes were designated “defective” under the Housing Defects Legislation. However, no steel or timber systems were classified as defective, which means they remain structurally sound but still require modern insulation solutions to meet today’s energy efficiency standards.

Types of non-traditional housing

Non-traditional housing can be split into four main categories:

1. Metal framed houses – e.g., B1 Aluminium Bungalow and BISF houses
2. Timber framed houses – e.g., Frameform houses
3. Precast concrete houses – e.g., Cornish Units and Airey houses
4. In-situ concrete houses – e.g., Wimpey No-Fines houses

1. Metal Framed Houses

• B1 Aluminium Bungalows (approx. 55,000 built)
• BISF Houses (approx. 35,000 built)

Metal framed houses often suffer from thermal bridging, where the metal frame conducts heat, leading to heat loss and condensation issues. Therefore, insulation must minimise this thermal transfer.

Insulation Solutions:

• External wall insulation (EWI): Adding insulation to the outside of the structure can reduce thermal bridging. Rigid foam boards or mineral wool covered with a protective render are commonly used for this method.
• Cavity wall insulation: For homes with a cavity between the metal frame and the outer wall, filling the cavity with materials like polyurethane foam or mineral wool can reduce heat loss.
• Roof insulation: Since metal roofs can lead to significant heat loss, using rigid insulation boards between the rafters or applying spray foam insulation directly to the underside of the roof can improve thermal efficiency.

2. Timber Framed Houses

• Frameform Houses (approx. 13,000 built)

Timber-framed homes often have thinner walls than traditional brick houses, which can result in less effective insulation. Timber is also susceptible to moisture, so it’s important to use breathable insulation materials to prevent condensation.

Insulation Solutions:

• Sheep’s wool insulation: A natural, breathable option that regulates humidity and provides excellent thermal performance.
• Hemp or cellulose insulation: These eco-friendly materials provide good thermal insulation while being breathable and moisture-resistant.
• External insulation: As with metal-framed houses, external insulation can be applied using rigid insulation boards or insulated render systems to increase the home’s energy efficiency.

3. Precast Concrete Houses

• Cornish Units (approx. 30,000 built)
• Airey Houses (approx. 26,000 built)

Precast concrete homes are known for their durability, but they often lack proper insulation. Heat loss through the concrete panels can lead to high energy bills and uncomfortable indoor temperatures.

Insulation Solutions:

• Internal wall insulation (IWI): Insulating the interior walls with rigid foam boards or insulated plasterboard helps reduce heat loss, although this can slightly reduce room sizes.
• External wall insulation (EWI): Like metal-framed homes, applying external insulation is a good option for precast concrete homes. Rigid insulation boards attached to the home’s exterior, followed by a render or cladding, can improve the building’s thermal performance.
• Cavity wall insulation (if applicable): Some precast concrete homes may have cavities that can be insulated with materials like blown-in cellulose or foam.

4. In-Situ Concrete Houses

• Wimpey No-Fines Homes (approx. 300,000 built)

Wimpey No-Fines homes are built using a mix of aggregate and cement, creating solid walls without a traditional cavity. These homes are known for their strength. However, they are difficult to insulate due to the lack of space between the walls.

Insulation Solutions:

• External wall insulation (EWI): External insulation is often the best approach for in-situ concrete homes. Mineral wool or polystyrene insulation boards can be affixed to the exterior, followed by render or cladding to protect the insulation and improve the appearance.
• Internal wall insulation (IWI): Internal wall insulation is also an option for homeowners who do not want to change the external appearance of their property. However, as insulation boards are applied to the inside of the external walls, this can reduce the size of rooms.
• Roof and loft insulation: Since heat rises, ensuring that the roof and loft are well insulated is crucial for Wimpey No-Fines homes. Mineral wool or rigid foam boards can also be installed in the loft to retain heat.