Introduction to the MOD Special House

The MOD Special house, a unique and historically significant property type, holds a special place in the UK’s architectural landscape. Designed by the Ministry of Defence (MOD) and constructed in the 1940s, these semi-detached bungalows were part of a post-war effort to address housing shortages. With only 43 units built, these properties are rare and carry a distinct set of characteristics and considerations for potential buyers and investors.

In this comprehensive guide, we will delve into the history, construction, typical characteristics, and potential hazards associated with MOD Special houses. We will also provide practical advice for inspecting these properties, ensuring you are well-informed before making a purchase.

Historical Context and Manufacturing Details

Origins and Purpose

The MOD Special house was conceived during the 1940s, a period marked by significant housing shortages in the UK due to the aftermath of World War II. The Ministry of Defence, in collaboration with various manufacturers, designed these homes to provide quick and efficient housing solutions for military personnel and their families.

Manufacturers and Designers

The primary designer of the MOD Special house was the Ministry of Defence. The construction was carried out by various contractors who adhered to the MOD’s specifications. The houses were built using prefabricated reinforced concrete (PRC) components, a popular construction method at the time due to its speed and cost-effectiveness.

Typical Locations

MOD Special houses are predominantly found in areas with a strong military presence, reflecting their original purpose. These locations include towns and cities near military bases and installations. Due to their limited number, they are considered rare and can be a unique addition to any property portfolio.

Characteristics of the MOD Special House

Architectural Features

MOD Special houses are semi-detached bungalows, a design choice that provided a balance between space efficiency and comfort. Here are some key architectural features:

• Flat Roof Covered with Asphalt: The flat roof design, covered with asphalt, was a practical choice for the time, offering ease of construction and maintenance.
• External Walls: The external walls are constructed using storey-height PRC columns infilled with precast concrete (PC) panels. This method provided structural integrity and speed of assembly.
• PRC Window Sills: The use of PRC window sills is a distinctive feature, contributing to the overall aesthetic and structural design.
• Header Tanks on Roof: The presence of header tanks located on the roof adjacent to the chimney stack is a unique characteristic, indicative of the property’s original design and purpose.

Construction Details

Understanding the construction details of MOD Special houses is crucial for assessing their condition and potential risks. Here is a breakdown of the typical construction elements:

• Substructure: The substructure consists of a brick underbuilding and a concrete slab, providing a solid foundation.
• External Walls: The external walls feature storey-height T-section PRC columns with PC panels slotted between adjacent columns, creating a cavity wall system.
• Ground Floor: The ground floor is made of concrete, offering durability and stability.
• Roof: The roof is constructed using tapered PRC beams and PRC panels, covered with asphalt for weatherproofing.

Variants

While the standard design of MOD Special houses includes a flat roof, some variants exist. These include:

• False Ceiling: Some properties may have a false ceiling finished with plasterboard, providing additional insulation and aesthetic appeal.
• Shallow Pitch Roof: A few variants feature a shallow pitch roof covered with concrete tiles, offering an alternative to the flat roof design.

Potential Hazards and Risks

Structural Concerns

One of the primary concerns with MOD Special houses is the potential for structural issues, particularly related to the use of PRC components. Over time, PRC can deteriorate, leading to various structural problems. Key risks include:

• Corrosion of Steel Reinforcement: The steel reinforcement within the PRC components can corrode, compromising the structural integrity of the property. This is particularly concerning in areas with high moisture levels.
• Carbonation: Carbonation, a chemical reaction between carbon dioxide and the concrete, can reduce the alkalinity of the concrete, leading to corrosion of the steel reinforcement.
• Spalling: Spalling, or the breaking away of concrete surfaces, can occur due to the expansion of corroded steel reinforcement. This can lead to visible cracks and weakened structural elements.

Defective Premises Act

MOD Special houses are not classified as defective under the Defective Premises Act. However, due to their age and construction method, they may still present significant risks that require careful assessment and potential remediation.

Inspection and Assessment Guide

Preparation for Inspection

Before inspecting an MOD Special house, it is essential to gather relevant information and prepare adequately. Here are some steps to follow:

• Review Historical Records: Obtain any available historical records or previous survey reports related to the property. This can provide valuable insights into past issues and repairs.
• Understand Construction Methods: Familiarize yourself with the construction methods used in MOD Special houses, particularly the use of PRC components and potential risks associated with them.

Inspection Checklist

When inspecting an MOD Special house, use the following checklist to ensure a thorough assessment:

• External Walls: Examine the external walls for signs of cracking, spalling, or other damage. Pay particular attention to the PRC columns and PC panels.
• Roof: Inspect the roof for any signs of water ingress, damage to the asphalt covering, or issues with the PRC beams and panels.
• Windows and Doors: Check the condition of the PRC window sills and frames. Look for any signs of deterioration or movement.
• Internal Walls and Partitions: Assess the internal walls and partitions for any signs of structural issues, such as cracks or movement.
• Floors: Inspect the concrete floors for any signs of cracking or unevenness. Check for any signs of moisture ingress or damage.
• Header Tanks: Examine the header tanks on the roof for any signs of leaks or damage. Ensure they are securely positioned and functioning correctly.

Special Considerations

When inspecting an MOD Special house, consider the following special considerations:

• Corrosion Assessment: Use appropriate tools and techniques to assess the extent of corrosion in the steel reinforcement. This may include visual inspection, hammer testing, or more advanced methods such as half-cell potential testing.
• Carbonation Testing: Conduct carbonation testing to determine the depth of carbonation in the concrete. This can help assess the risk of steel reinforcement corrosion.
• Moisture Assessment: Check for any signs of moisture ingress, particularly in areas prone to water exposure, such as the roof and external walls.

Typical Defects and Maintenance

Common Defects

MOD Special houses are prone to several common defects due to their age and construction method. These include:

• Cracking and Spalling: Cracking and spalling of the concrete components are common issues, often resulting from corrosion of the steel reinforcement.
• Water Ingress: Water ingress can occur through the roof, external walls, or windows, leading to moisture-related issues such as dampness and mould.
• Structural Movement: Structural movement, such as settlement or shifting of the PRC columns, can lead to visible cracks and misalignment of components.

Maintenance and Repair

Regular maintenance and timely repairs are essential to preserve the structural integrity and value of an MOD Special house. Here are some maintenance and repair tips:

• Regular Inspections: Conduct regular inspections to identify and address any emerging issues promptly. This can help prevent minor problems from escalating into major defects.
• Corrosion Protection: Implement corrosion protection measures, such as applying protective coatings to the steel reinforcement or using corrosion inhibitors.
• Concrete Repairs: Repair any cracks or spalling in the concrete components using appropriate repair methods and materials. This may include patching, resurfacing, or replacing damaged sections.
• Waterproofing: Ensure the roof and external walls are adequately waterproofed to prevent water ingress. This may involve repairing or replacing the asphalt covering, sealing joints, and addressing any leaks.

Conclusion

The MOD Special house is a unique and historically significant property type that offers both opportunities and challenges for home buyers and investors. Understanding the construction methods, potential hazards, and maintenance requirements is crucial for making informed decisions and safeguarding your 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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