Understanding the Concept 4 House

The Concept 4 house, also known simply as “Concept,” is a distinctive type of system-built property that emerged in the 1960s. Designed by the John West Design Group, this property type was part of a broader movement towards innovative construction methods aimed at addressing the post-war housing shortage in the UK. With only 120 units built, these properties are relatively rare, making them a unique find for home buyers and investors.

Historical Context and Manufacturing

Period and Location

The Concept 4 houses were constructed during the 1960s, a period marked by a significant demand for affordable and quickly built housing solutions. These properties are typically found in suburban areas, where there was ample space for new housing developments. The design and construction methods were influenced by the need for rapid assembly and cost-effectiveness.

Manufacturers and Designers

The John West Design Group was the primary designer behind the Concept 4 houses. Their innovative approach to system building allowed for the efficient production of these homes. The construction process involved prefabricated components, which were assembled on-site, reducing the overall build time and labour costs.

Identifying Characteristics

Architectural Features

Concept 4 houses come in various forms, including bungalows, two-storey, and three-storey semi-detached and terraced houses. They are easily identifiable by their shallow pitch gable, monopitch, or flat roofs, which are typically covered with bituminous felt or aluminium sheets. The front and rear external walls are clad with horizontal timber boarding, giving these homes a distinctive appearance.

External Walls and Windows

The gable walls of Concept 4 houses are constructed from storey-height exposed aggregate precast concrete (PC) panels. These panels often feature a small window in the timber-clad stub wall at the junction of roof pitches in double roof pitch houses. This unique combination of materials and design elements makes the Concept 4 house stand out from other properties of the same era.

Construction Details

Substructure

The substructure of a Concept 4 house consists of a concrete slab that is thickened under the cross walls and front and rear walls. A damp-proof course (DPC) is included to prevent moisture from rising through the structure.

External Walls

The front and rear walls are made from storey-height timber frame panels, which are clad with horizontal timber boarding and lined with plasterboard. The gable walls are constructed from storey-height exposed aggregate 8-inch (Lytag) PC panels with grooved edges to receive reinforced concrete (RC) fill. Mastic pointing is used to seal joints and prevent water ingress.

Internal Walls and Partitions

The separating walls between properties are made from storey-height 8-inch (Lytag) PC panels. Internal partitions are constructed from timber studs lined with plasterboard, providing a lightweight and flexible solution for dividing internal spaces.

Floors and Ceilings

The ground floor of a Concept 4 house is typically made from concrete, while the upper floors consist of timber boarding on timber joists. Ceilings are lined with plasterboard, providing a smooth and durable finish.

Roof

The roof structure is made from prefabricated timber units, covered with chipboard and bituminous felt. In some variants, the roof cover is made from aluminium sheets, offering an alternative to the standard bituminous felt.

Services

Services such as plumbing and electrical systems are confined to a central position within the property, using timber frame ‘heart’ units. This centralised approach simplifies the installation and maintenance of essential services.

Typical Hazards and Risks

Structural Concerns

One of the primary concerns with Concept 4 houses is the durability of the reinforced concrete components. Over time, these elements can be susceptible to corrosion, particularly if they are exposed to moisture. The BRE Digest 444 provides guidance on the inspection and assessment of reinforced concrete durability, which is essential for identifying potential issues.

Timber Decay

The extensive use of timber in the construction of Concept 4 houses means that these properties are at risk of timber decay, particularly if they are not adequately maintained. Regular inspections and maintenance are crucial to prevent issues such as rot and insect infestation.

Thermal Performance

The original design of Concept 4 houses did not prioritise thermal performance, meaning that these properties can be less energy-efficient compared to modern homes. Upgrading insulation and installing energy-efficient windows can help to improve the thermal performance of these properties.

Defective Premises Act

Classification

The Concept 4 house is not classed as defective under the Defective Premises Act. However, it is essential to be aware of the potential issues associated with this property type and to carry out thorough inspections before purchasing.

Inspection and Assessment

Step-by-Step Guide for Surveyors

1. Initial Visual Inspection: Begin with a thorough visual inspection of the property, noting any obvious signs of damage or deterioration. Pay particular attention to the condition of the external timber cladding and the exposed aggregate PC panels.

2. Check for Moisture Ingress: Inspect the DPC and mastic pointing for any signs of failure, which could allow moisture to penetrate the structure. Use a moisture meter to check for elevated moisture levels in the timber components.

3. Assess Reinforced Concrete Durability: Refer to the BRE Digest 444 for guidance on assessing the durability of the reinforced concrete components. Look for signs of corrosion, such as rust stains or spalling concrete.

4. Inspect Timber Components: Check for signs of timber decay, including rot and insect infestation. Pay particular attention to areas where timber components are in contact with the ground or exposed to moisture.

5. Evaluate Thermal Performance: Assess the insulation levels in the walls, roof, and floors. Consider recommending upgrades to improve the property’s energy efficiency.

6. Check Services: Inspect the centralised services for any signs of wear or damage. Ensure that plumbing and electrical systems are up to current standards and functioning correctly.

Typical Defects and Maintenance

Common Issues

1. Timber Cladding Deterioration: Over time, the horizontal timber boarding can become weathered and may require repainting or replacement. Regular maintenance is essential to protect the timber from moisture and UV damage.

2. Concrete Panel Cracking: The exposed aggregate PC panels can develop cracks due to thermal movement or structural stress. These cracks should be monitored and repaired to prevent water ingress and further deterioration.

3. Roof Covering Wear: The bituminous felt or aluminium sheets used for the roof covering can degrade over time, leading to leaks. Regular inspections and timely repairs are necessary to maintain the roof’s integrity.

4. Insulation Deficiencies: The original insulation in Concept 4 houses may be inadequate by modern standards. Upgrading the insulation can improve the property’s energy efficiency and reduce heating costs.

Maintenance Tips

1. Regular Inspections: Conduct regular inspections of the property to identify and address any issues early. This proactive approach can help to prevent more significant problems from developing.

2. Timber Treatment: Apply protective treatments to the timber cladding to prevent decay and extend its lifespan. Ensure that any damaged or decayed timber is replaced promptly.

3. Concrete Repairs: Use appropriate repair methods for any cracks or damage to the concrete panels. Ensure that repairs are carried out by qualified professionals to maintain the structural integrity of the property.

4. Roof Maintenance: Regularly inspect the roof covering for signs of wear and tear. Replace any damaged sections promptly to prevent leaks and water damage.

Conclusion

The Concept 4 house represents a unique and innovative approach to post-war housing in the UK. While these properties have their challenges, they also offer a distinctive architectural style and historical significance. By understanding the typical characteristics, potential hazards, and maintenance requirements of Concept 4 houses, home buyers and investors can make informed decisions and ensure the longevity of their investment.

At Flettons, we’re committed to safeguarding your investment. When considering a property purchase, trust our seasoned expertise to reveal any hidden threats. For a thorough building survey, get your instant quote through our quote calculator or reach out directly at 0203 691 0451. Your home’s safety is our top priority.

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