Historical Context and Manufacturing Background

The Tarran Temporary Bungalow, often referred to as a “Prefab” or “Tarran Mark IV,” is a notable example of post-World War II British housing. These bungalows were manufactured by Tarran Industries Ltd, under the design leadership of R Tarran, and were constructed between 1944 and 1956. The primary aim was to address the acute housing shortage that followed the war, providing quick and affordable homes for displaced families and returning soldiers.

Approximately 8,000 of these bungalows were built, including variants like the Dorran, Myton, and Newland. These homes were predominantly located in urban and suburban areas across the UK, where the need for rapid housing solutions was most pressing.

Design and Construction Characteristics

External Features

The Tarran Temporary Bungalow is easily identifiable by its detached, single-storey structure. The roof is a shallow pitch gable, typically covered with profiled asbestos cement sheets. This roofing material was chosen for its durability and cost-effectiveness, although it poses significant health risks today due to asbestos content.

The external walls are constructed from storey-height aggregate-faced Precast Reinforced Concrete (PRC) panels. These panels are bolted through timber posts and backed with bituminous felt, insulation, and plasterboard. A metal cowl is often present on the chimney, adding to the distinctive look of these bungalows.

Internal Features

Internally, the bungalows feature timber stud partitions lined with plasterboard. The ground floor is constructed from tongue-and-groove (T&G) boarding on timber joists, providing a solid yet flexible foundation. Ceilings are also plasterboard, contributing to the overall lightweight construction of the building.

The roof structure consists of timber frame wedge-shaped units bolted to central partitions and external walling, covered with profiled asbestos cement sheets. Waterproof insulation is installed at ceiling level to enhance thermal efficiency.

Substructure

The substructure of the Tarran Temporary Bungalow is a concrete raft foundation. This type of foundation was chosen for its ability to provide a stable base on various soil types, reducing the risk of subsidence and other ground-related issues.

Typical Hazards and Risks

Asbestos

One of the most significant hazards associated with Tarran Temporary Bungalows is the presence of asbestos in the roofing materials. Asbestos was widely used in construction during the mid-20th century due to its fire-resistant properties. However, it is now known to be a severe health risk, causing diseases such as asbestosis, lung cancer, and mesothelioma. Homeowners and investors should be aware of the potential need for asbestos removal, which can be costly and requires specialist contractors.

Carbonation of PRC Panels

The PRC panels used in the construction of these bungalows are prone to carbonation, a process where carbon dioxide from the air reacts with the calcium hydroxide in the concrete, forming calcium carbonate. This reaction reduces the alkalinity of the concrete, leading to the corrosion of embedded steel reinforcement. High rates of carbonation have been observed on the internal surfaces of PRC panels, while the external surfaces exhibit lower rates. This differential carbonation can lead to structural weaknesses over time.

Cracking and Spalling

Cracking and spalling of PRC panels and columns are common issues in Tarran Temporary Bungalows. Spalling occurs when the surface of the concrete flakes off, often due to the expansion of corroded steel reinforcement. This not only affects the aesthetic appeal of the property but also compromises its structural integrity.

Timber Rot

The timber components of the bungalow, including the kerb and wall plate, are susceptible to rot, especially if they have been exposed to moisture. Timber rot can weaken the structural framework, leading to potential safety hazards.

Defective Premises Act and Designation

The Tarran Temporary Bungalow is classified as defective under the Defective Premises Act. This designation means that the property does not meet the required standards of safety and habitability, primarily due to the issues outlined above. As a result, these properties are often considered less desirable by lenders and insurers, making it challenging to secure financing or insurance coverage.

Inspection Guide for Surveyors

When inspecting a Tarran Temporary Bungalow, surveyors should pay close attention to the following areas:

Roof

• Asbestos Cement Sheets: Check for signs of wear, damage, or deterioration. Asbestos removal may be necessary if the material is in poor condition.
• Timber Frame: Inspect for signs of rot or insect infestation. Ensure that the timber frame is structurally sound.

External Walls

• PRC Panels: Look for signs of cracking, spalling, or other damage. Assess the extent of carbonation and its impact on the structural integrity of the panels.
• Timber Posts: Check for rot or damage, particularly at the base where moisture exposure is more likely.

Internal Walls and Partitions

• Plasterboard: Inspect for signs of damp, mould, or damage. Ensure that the plasterboard is securely attached to the timber studs.
• Timber Studs: Check for signs of rot or insect infestation. Ensure that the studs are structurally sound.

Floors

• T&G Boarding: Inspect for signs of wear, damage, or warping. Ensure that the boarding is securely attached to the timber joists.
• Timber Joists: Check for signs of rot or insect infestation. Ensure that the joists are structurally sound.

Substructure

• Concrete Raft Foundation: Look for signs of cracking, subsidence, or other damage. Assess the overall stability of the foundation.

Common Defects and Remedial Measures

Carbonation and Corrosion

To address carbonation and corrosion of PRC panels, it may be necessary to apply a protective coating to the concrete surfaces. This can help to reduce the rate of carbonation and protect the embedded steel reinforcement. In severe cases, it may be necessary to replace the affected panels entirely.

Cracking and Spalling

Cracks and spalling can be repaired using specialist concrete repair techniques. This may involve removing the damaged concrete, treating the corroded steel reinforcement, and applying a suitable repair mortar. Regular maintenance and inspections can help to identify and address these issues before they become more severe.

Timber Rot

Timber rot can be treated using specialist wood preservatives and repair techniques. In cases where the rot is extensive, it may be necessary to replace the affected timber components entirely. Ensuring that the property is well-ventilated and protected from moisture can help to prevent timber rot from occurring in the first place.

Asbestos Removal

Asbestos removal should only be carried out by licensed contractors. The process involves carefully removing the asbestos-containing materials and disposing of them in accordance with strict regulations. It is essential to ensure that the property is safe and free from asbestos before carrying out any renovation or repair work.

Conclusion

The Tarran Temporary Bungalow is a fascinating example of post-war British housing, offering a unique blend of historical significance and practical challenges. While these properties can present a range of hazards and defects, they also offer potential opportunities for renovation and 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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