Understanding the Grid House

The Grid House, also known as RM housing, is a distinctive type of system-built property that emerged in the mid-20th century. Designed and manufactured by Morrison and Partners, these homes were constructed in 1966, with a total of 160 units built. Predominantly found in various parts of the UK, these properties are known for their unique construction methods and materials. This article delves into the essential aspects of Grid Houses, providing valuable insights for home buyers and investors.

Historical Context and Manufacturing

Origins and Development

The Grid House was developed during a period when the UK faced a significant housing shortage. Post-World War II, there was an urgent need for quick and cost-effective housing solutions. Morrison and Partners, a prominent name in the construction industry, took on the challenge and designed the Grid House. These homes were part of a broader movement towards system-built properties, which aimed to streamline construction processes and reduce costs.

Manufacturing and Design

Morrison and Partners were both the designers and manufacturers of the Grid House. Their approach involved using prefabricated components that could be quickly assembled on-site. This method not only sped up the construction process but also ensured consistency in quality. The design of the Grid House was innovative for its time, incorporating modern materials and construction techniques.

Typical Characteristics of Grid Houses

Structural Features

Grid Houses are typically two-storey buildings, available in detached, semi-detached, and terraced configurations. One of the most distinctive features is the flat roof, which is covered with plastic sheets. The external walls are made of storey-height timber frame infill panels, which are clad with various materials such as tile or slate hanging, horizontal timber boarding, coloured asbestos cement sheets, aluminium or plastic sheets, or concrete panels.

Identification Characteristics

• External Walls: The walls are clad with a variety of materials, including tile or slate hanging, horizontal timber boarding, coloured asbestos cement sheets, aluminium or plastic sheets, or concrete panels.
• Corners: Vertical cover strips are present at the corners of the building.
• Fascia Panels: These panels encircle the dwelling at the eaves level.
• Concrete Apron: A concrete apron surrounds the perimeter of the building.

Internal Features

• Substructure: Concrete pads are located below stanchion locations, with a concrete slab thickened around the perimeter.
• Frame: The frame consists of 9 RS hollow box stanchions, 4 RSC floor support beams, and 4 RSC roof support beams.
• External Walls: Storey-height timber frame infill panels are clad with horizontal timber boarding over building paper and lined with honeycomb plasterboard. Mineral wool insulation is placed between frame studs.
• Separating Wall: Made of masonry.
• Partitions: Constructed from honeycomb plasterboard.
• Ground Floor: Concrete.
• First Floor: Chipboard on timber joists.
• Ceilings: Plasterboard.
• Roof: Timber joists, plywood, and plastic sheets.

Typical Hazards and Risks

Asbestos Concerns

One of the primary concerns with Grid Houses is the presence of asbestos cement sheets in the external cladding. Asbestos was commonly used in construction during the 1960s due to its fire-resistant properties. However, it is now known to pose significant health risks if disturbed. Home buyers and investors should be aware of the potential presence of asbestos and consider professional asbestos surveys and removal if necessary.

Structural Integrity

The timber frame construction, while innovative, can be susceptible to issues such as rot and insect infestation. Over time, moisture can penetrate the timber, leading to decay and compromising the structural integrity of the building. Regular inspections and maintenance are crucial to ensure the longevity of the property.

Insulation and Energy Efficiency

Grid Houses were built with mineral wool insulation between the frame studs. While this was adequate at the time, modern standards for energy efficiency have evolved. Upgrading the insulation and improving the overall energy efficiency of the property can be beneficial for reducing energy costs and enhancing comfort.

Legal Considerations

Defective Premises Act

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 Grid Houses are not specifically listed as defective under this act, the potential issues related to asbestos, timber decay, and insulation should be carefully considered. Home buyers and investors should seek professional advice and conduct thorough surveys to identify any defects and necessary repairs.

Inspection and Assessment

Preparing for an Inspection

When inspecting a Grid House, it is essential to be well-prepared and equipped with the right knowledge and tools. Here are some key steps to follow:

1. Review Historical Data: Familiarise yourself with the construction history and typical characteristics of Grid Houses. This will help you identify potential issues and areas that require closer inspection.
2. Gather Tools and Equipment: Ensure you have the necessary tools, such as a moisture meter, flashlight, ladder, and personal protective equipment (PPE) for asbestos inspection.
3. Check for Documentation: Request any available documentation from the current owner, such as previous survey reports, maintenance records, and asbestos surveys.

Conducting the Inspection

1. External Inspection:
2. Roof: Check the condition of the flat roof and plastic sheets. Look for signs of wear, damage, or leaks.
3. Walls: Inspect the cladding materials for any signs of damage, decay, or asbestos. Pay close attention to the vertical cover strips at the corners.
4. Fascia Panels: Examine the fascia panels for any signs of deterioration or damage.

5. Concrete Apron: Check the condition of the concrete apron around the perimeter of the building.

6. Internal Inspection:

7. Substructure: Inspect the concrete pads and slab for any signs of cracking or movement.
8. Frame: Check the condition of the timber frame, looking for signs of rot, insect infestation, or damage.
9. Walls: Inspect the internal walls for any signs of moisture, decay, or damage to the honeycomb plasterboard.
10. Floors: Check the condition of the ground floor concrete and the first-floor chipboard on timber joists.
11. Ceilings: Inspect the plasterboard ceilings for any signs of damage or moisture.
12. Roof: Examine the timber joists, plywood, and plastic sheets for any signs of wear or damage.

Reporting and Recommendations

After completing the inspection, compile a detailed report outlining your findings. Highlight any areas of concern, such as the presence of asbestos, timber decay, or structural issues. Provide recommendations for necessary repairs, maintenance, or further investigations. Ensure that the report is clear, concise, and easy to understand for the home buyer or investor.

Typical Defects and Maintenance

Common Defects

1. Asbestos: As mentioned earlier, the presence of asbestos cement sheets in the external cladding is a significant concern. If asbestos is found, it is crucial to engage a professional for safe removal and disposal.
2. Timber Decay: The timber frame construction can be prone to rot and insect infestation. Regular inspections and maintenance are essential to prevent and address these issues.
3. Moisture Penetration: Moisture can penetrate the timber frame and cause decay. Ensure that the building is adequately sealed and that any leaks or water ingress are promptly addressed.
4. Insulation: The original mineral wool insulation may not meet modern energy efficiency standards. Upgrading the insulation can improve energy efficiency and comfort.

Maintenance Tips

1. Regular Inspections: Conduct regular inspections of the property to identify and address any issues early. Pay close attention to the roof, external cladding, and timber frame.
2. Asbestos Management: If asbestos is present, ensure that it is managed safely and in accordance with regulations. Engage a professional for any removal or remediation work.
3. Timber Treatment: Treat the timber frame with appropriate preservatives to prevent rot and insect infestation. Ensure that any damaged timber is repaired or replaced promptly.
4. Moisture Control: Implement measures to control moisture and prevent water ingress. This may include sealing gaps, repairing leaks, and ensuring proper drainage around the property.
5. Insulation Upgrades: Consider upgrading the insulation to improve energy efficiency and reduce heating costs. Modern insulation materials can provide better thermal performance and comfort.

Variants of Grid Houses

Alternative Cladding Materials

While the typical Grid House features timber frame infill panels clad with horizontal timber boarding, there are variants with different cladding materials. These include:

• Tile or Slate Hanging: Provides a traditional and aesthetically pleasing appearance.
• Coloured Asbestos Cement Sheets: Commonly used during the 1960s but now known to pose health risks.
• Aluminium or Plastic Sheets: Lightweight and durable options that require minimal maintenance.
• Concrete Panels: Provide a robust and durable cladding solution.

Identifying Variants

When inspecting a Grid House, it is essential to identify the specific variant and cladding materials used. This will help you assess the potential risks and maintenance requirements. Pay close attention to the external walls and cladding materials, and refer to historical data and documentation for additional information.

Conclusion

The Grid House, designed and manufactured by Morrison and Partners in 1966, represents a unique and innovative approach to system-built housing. While these properties offer several advantages, such as quick construction and cost-effectiveness, they also come with potential risks and maintenance challenges. Home buyers and investors should be aware of the typical characteristics, hazards, and legal considerations associated with Grid Houses.

By conducting thorough inspections, addressing any defects, and implementing regular maintenance, you can ensure the longevity and safety of 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.