The Rise of Engineered Homes

Engineered Homes, a distinctive type of system-built property, emerged in the UK during the late 1960s and early 1970s. Manufactured by Engineered Homes (Great Britain) Ltd, these properties were designed by R Griffiths, I Lewis and Partners, L Vincent, and R Gorbing and Partners. Built between 1966 and 1971, approximately 800 of these homes were constructed. Known alternatively as Parkway homes, they are primarily found in suburban areas across the UK.

Identifying Engineered Homes

Engineered Homes are easily identifiable by their architectural features. They include bungalows and two-storey semi-detached and terraced houses. A medium pitch gable roof covered with tiles is a common characteristic. The external walls are rendered throughout, and a horizontal timber boarded feature panel is typically found beneath the window frames on the front elevation. Additionally, these homes often have a flat canopy over the front door, adding to their unique aesthetic.

Construction Details

Understanding the construction of Engineered Homes is crucial for potential buyers and investors. These homes are built on concrete slab footings with a damp-proof course (DPC) to prevent moisture ingress. The external walls are constructed using a platform frame method, consisting of storey-height timber frame panels sheathed externally with plywood. This is overlaid with building paper and directly clad with rendered expanded steel mesh. A horizontal timber boarded feature panel is positioned beneath the front elevation windows.

Internally, the walls are lined with plasterboard over a polyethylene vapour control layer, with mineral fibre insulation between the frame studs. The separating wall is a timber frame cavity wall, backed with plywood and lined with two layers of plasterboard. Paper laminated mineral fibre insulation fills the cavity, providing thermal efficiency.

The ground floor is typically concrete, while the first floor consists of plywood on timber joists. Ceilings are plasterboard, and the roof is constructed with timber trusses, bituminous felt, and tiles. Mineral fibre insulation and a polyethylene vapour control layer are installed at ceiling level to enhance energy efficiency.

Variants and Alternatives

Some variants of Engineered Homes feature a suspended timber ground floor instead of concrete. In bungalows, the rendered expanded steel mesh cladding is applied throughout. Additionally, macerated paper insulation may be used at ceiling level in the roof space, offering an alternative to mineral fibre insulation.

Typical Characteristics and Hazards

While Engineered Homes offer unique architectural features, they also present certain risks and hazards. Localised wetting of horizontal timber boarding at the foot of external walls is a common issue. Cracking of render and corrosion of expanded metal lathing can also occur, potentially compromising the structural integrity of the property.

Another concern is the localised omission of the polyethylene vapour control layer, which can lead to moisture ingress and subsequent damage. Slumping of mineral fibre insulation between panel studs is another issue, reducing the thermal efficiency of the home. Additionally, the packing of mineral fibre or macerated paper insulation can prevent proper roof ventilation, leading to condensation and potential mould growth.

Impaired fire stopping at the separating wall in the roof space is a significant safety concern, as it can allow fire to spread more easily between properties. Rain penetration at window flashings is another common issue, which can lead to water damage and deterioration of the building fabric.

Defective Premises Act Considerations

When considering the purchase of an Engineered Home, it is essential to understand whether the property is classed as defective under the Defective Premises Act. This legislation aims to protect homeowners from substandard construction practices that could pose a risk to health and safety. While Engineered Homes are not inherently classed as defective, the presence of certain defects, such as those mentioned above, could potentially lead to classification under this act.

Inspection Tips for Surveyors

For surveyors inspecting Engineered Homes, a thorough understanding of the construction and potential defects is crucial. Begin by examining the external walls for signs of cracking or corrosion in the render and expanded metal lathing. Check for localised wetting of horizontal timber boarding at the foot of the walls, as this can indicate moisture ingress.

Inspect the roof space for impaired fire stopping at the separating wall and ensure that proper ventilation is maintained to prevent condensation. Examine the insulation between panel studs for slumping or packing that could impede ventilation. Additionally, check window flashings for signs of rain penetration and address any issues promptly.

Roof Construction

The roof of an Engineered Home is constructed using timber trusses, bituminous felt, and tiles. This design provides a robust and weather-resistant covering for the property. However, it is essential to ensure that the mineral fibre insulation and polyethylene vapour control layer at ceiling level are intact and functioning correctly. This will help maintain energy efficiency and prevent condensation issues.

Wall Construction

The external walls of Engineered Homes are built using a platform frame construction method. Storey-height timber frame panels are sheathed externally with plywood, overlaid with building paper, and directly clad with rendered expanded steel mesh. A horizontal timber boarded feature panel is positioned beneath the front elevation windows, adding to the property’s unique aesthetic.

Internally, the walls are lined with plasterboard over a polyethylene vapour control layer, with mineral fibre insulation between the frame studs. This construction method provides good thermal efficiency and sound insulation, making Engineered Homes a comfortable living environment.

Floor Construction

The ground floor of an Engineered Home is typically concrete, providing a solid and durable base for the property. The first floor consists of plywood on timber joists, offering a lightweight yet sturdy construction. In some variants, a suspended timber ground floor may be used, providing an alternative to the traditional concrete base.

Common Defects in Engineered Homes

While Engineered Homes offer many benefits, they are not without their potential defects. Localised wetting of horizontal timber boarding at the foot of external walls is a common issue, often caused by inadequate drainage or poor maintenance. Cracking of render and corrosion of expanded metal lathing can also occur, potentially compromising the structural integrity of the property.

The localised omission of the polyethylene vapour control layer can lead to moisture ingress and subsequent damage. Slumping of mineral fibre insulation between panel studs is another issue, reducing the thermal efficiency of the home. Additionally, the packing of mineral fibre or macerated paper insulation can prevent proper roof ventilation, leading to condensation and potential mould growth.

Impaired fire stopping at the separating wall in the roof space is a significant safety concern, as it can allow fire to spread more easily between properties. Rain penetration at window flashings is another common issue, which can lead to water damage and deterioration of the building fabric.

Maintenance and Repair Tips

To maintain the integrity and value of an Engineered Home, regular maintenance and timely repairs are essential. Address any signs of cracking or corrosion in the render and expanded metal lathing promptly to prevent further damage. Ensure that horizontal timber boarding at the foot of external walls is adequately protected from moisture ingress.

Inspect the roof space regularly to ensure that proper ventilation is maintained and that insulation is not slumping or packed too tightly. Address any issues with window flashings to prevent rain penetration and water damage.

Energy Efficiency Considerations

Engineered Homes are designed with energy efficiency in mind, thanks to their timber frame construction and insulation. However, maintaining this efficiency requires regular inspection and maintenance. Ensure that the polyethylene vapour control layer is intact and functioning correctly to prevent moisture ingress and heat loss.

Check the insulation between panel studs for slumping or packing that could reduce thermal efficiency. Additionally, ensure that the roof space is adequately ventilated to prevent condensation and maintain a comfortable living environment.

Fire Safety Considerations

Fire safety is a critical consideration for any property, and Engineered Homes are no exception. Ensure that fire stopping at the separating wall in the roof space is intact and functioning correctly. This will help prevent the spread of fire between properties and protect the safety of occupants.

Regularly inspect smoke alarms and fire extinguishers to ensure they are in good working order. Additionally, create a fire escape plan and ensure that all occupants are familiar with it.

Conclusion

Engineered Homes offer a unique and attractive option for property buyers and investors in the UK. With their distinctive architectural features and energy-efficient design, they provide a comfortable and sustainable living environment. However, potential buyers should be aware of the common defects and hazards associated with these properties and take steps to address them promptly.

By understanding the construction and maintenance requirements of Engineered Homes, buyers can make informed decisions and protect their investment. Regular inspections and timely repairs will help maintain the integrity and value of the property, ensuring a safe and comfortable living environment for years to come.

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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