Historical Context and Background

The Arup house, a notable example of post-war British architecture, was designed by the renowned architectural firm Yorke Rosenberg and Mardall. Constructed in 1947, these properties were part of the broader effort to address the housing shortage in the UK following World War II. The Arup house is a system-built property, a term that refers to homes constructed using pre-fabricated components. This method was particularly popular in the mid-20th century due to its efficiency and cost-effectiveness.

The Arup house is typically a two-storey detached property, identifiable by its flat roof covered with bituminous felt, a front wall of brick, and a rear wall of timber frame infill panels clad with asbestos cement sheets. The flank wall is rendered throughout, often with a Tyrolean finish, and a small kerb runs along the perimeter of the roof slab. These houses were primarily built in urban and suburban areas, providing affordable housing solutions for many families.

Designers and Manufacturers

The Arup house was designed by Yorke Rosenberg and Mardall, a prominent architectural firm known for their innovative approach to modernist architecture. The firm played a significant role in the post-war reconstruction efforts, contributing to various housing projects across the UK. The construction of Arup houses was overseen by Arup, a global engineering and design consultancy firm. Arup’s expertise in structural engineering ensured that these houses were built to last, despite the challenges posed by the post-war environment.

Typical Characteristics and Hazards

Construction Details

Roof

The roof of an Arup house is a 6-inch reinforced concrete (RC) slab without falls, covered with bituminous felt. This flat roof design was a common feature in post-war architecture, offering a modern aesthetic and efficient use of materials.

Walls

• Front Wall: The front wall is constructed of 4 1/2-inch brick, with a cavity and 2-inch clay blocks. Metal wall ties are used to secure the structure.
• Rear Wall: The rear wall consists of 1 1/4-inch timber frame infill panels clad with asbestos cement sheets. These panels are lined with plasterboard, with sawdust/paper pulp insulation slabs between the frame studs.
• Flank Wall: The flank wall is rendered with Tyrolean finish, made of 8-inch dense aggregate RC, with a cavity and 1-inch timber battens lined with fibreboard.

Floors

• Ground Floor: The ground floor is a screed on bituminous damp-proof membrane (DPM) on an RC slab.
• First Floor: The first floor is a 6-inch RC slab.

Partitions

• Loadbearing Partitions: These are made of 4-inch dense aggregate concrete.
• Non-loadbearing Partitions: These are timber stud partitions lined with plasterboard.

Typical Hazards and Risks

Asbestos

One of the most significant hazards associated with Arup houses is the presence of asbestos cement sheets in the rear wall. Asbestos was commonly used in construction during the mid-20th century due to its fire-resistant properties. However, it is now known to pose serious health risks if disturbed. Asbestos fibres can cause lung diseases, including asbestosis, lung cancer, and mesothelioma. It is crucial to have a professional asbestos survey conducted before any renovation or demolition work.

Corrosion of Steel Reinforcement

The reinforced concrete used in the construction of Arup houses is susceptible to corrosion, particularly in the presence of moisture. Over time, this can lead to structural weaknesses and potential safety hazards. Regular inspections and maintenance are essential to ensure the longevity and safety of the property.

Insulation and Energy Efficiency

The insulation materials used in Arup houses, such as sawdust and paper pulp, are not as effective as modern insulation solutions. This can result in higher energy costs and reduced thermal comfort. Upgrading the insulation can significantly improve the energy efficiency of the property.

Defective Premises Act and Classification

The Defective Premises Act 1972 imposes a duty on builders, developers, and landlords to ensure that properties are constructed and maintained to a reasonable standard. While Arup houses were built to address the urgent housing needs of the post-war period, some of their construction methods and materials may not meet modern standards.

Arup houses are not universally classified as defective under the Defective Premises Act. However, the presence of asbestos and potential issues with reinforced concrete durability can raise concerns. It is advisable to have a thorough building survey conducted by a qualified surveyor to assess the condition of the property and identify any potential defects.

Inspection Guide for Surveyors

When inspecting an Arup house, surveyors should pay close attention to the following areas:

Roof

• Bituminous Felt: Check for signs of wear and tear, such as cracks, blisters, or leaks. The flat roof design can lead to water pooling, which can accelerate deterioration.
• Reinforced Concrete Slab: Inspect for signs of corrosion or structural damage. Look for cracks, spalling, or exposed reinforcement.

External Walls

• Brickwork: Examine the front wall for signs of cracking, movement, or deterioration of mortar joints.
• Asbestos Cement Sheets: Check the rear wall for any damage or disturbance to the asbestos cement sheets. Ensure that any asbestos-containing materials are handled by licensed professionals.
• Rendered Flank Wall: Inspect the Tyrolean render for cracks, delamination, or water ingress.

Floors

• Ground Floor: Check for signs of dampness or moisture ingress, particularly around the edges of the RC slab.
• First Floor: Inspect the RC slab for any signs of cracking or structural movement.

Partitions

• Loadbearing Partitions: Examine for any signs of cracking or movement in the dense aggregate concrete.
• Non-loadbearing Partitions: Check the timber stud partitions for signs of dampness, rot, or damage to the plasterboard.

Insulation

• Sawdust/Paper Pulp Insulation: Assess the effectiveness of the insulation and consider upgrading to modern materials for improved energy efficiency.

Typical Defects and Maintenance

Common Defects

• Asbestos-Related Issues: As mentioned earlier, the presence of asbestos cement sheets in the rear wall is a significant concern. Any disturbance to these materials should be handled by licensed professionals.
• Corrosion of Reinforcement: The reinforced concrete used in the construction of Arup houses is prone to corrosion, particularly in the presence of moisture. Regular inspections and maintenance are essential to prevent structural issues.
• Dampness and Moisture Ingress: The flat roof design and the use of bituminous felt can lead to water pooling and potential leaks. Regular maintenance of the roof covering is crucial to prevent water ingress.
• Insulation Inefficiency: The sawdust and paper pulp insulation used in Arup houses is not as effective as modern insulation materials. Upgrading the insulation can significantly improve the energy efficiency of the property.

Maintenance Tips

• Roof Maintenance: Regularly inspect the bituminous felt covering for signs of wear and tear. Address any issues promptly to prevent water ingress and potential damage to the reinforced concrete slab.
• Asbestos Management: If asbestos-containing materials are present, ensure that they are regularly inspected and maintained by licensed professionals. Avoid any disturbance to these materials to prevent the release of harmful fibres.
• Concrete Repairs: Address any signs of corrosion or structural damage to the reinforced concrete promptly. Regular inspections and maintenance can help prevent more significant issues.
• Insulation Upgrades: Consider upgrading the insulation to modern materials for improved energy efficiency and thermal comfort.

Conclusion

The Arup house is a unique example of post-war British architecture, offering a glimpse into the innovative construction methods used to address the housing shortage of the time. While these properties have stood the test of time, they do come with certain risks and challenges, particularly related to asbestos and reinforced concrete durability.

For home buyers and investors, it is essential to conduct a thorough building survey to assess the condition of the property and identify any potential defects. Regular maintenance and upgrades can help ensure the longevity and safety of an Arup house, making it a valuable investment for the future.

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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