Historical Context and Origins

The Duplex Sheath house, a unique architectural marvel, was introduced in 1924 by the Duplex-Sheath Construction Co. Ltd. This property type is a testament to the innovative spirit of early 20th-century construction, reflecting a blend of practicality and aesthetic appeal. The Duplex Sheath house is a rare find, with only one known to have been built, making it a significant piece of architectural history.

Designers and Manufacturers

The Duplex-Sheath Construction Co. Ltd., the brainchild behind this distinctive property, aimed to revolutionize residential construction. The designers, whose names remain less documented, were undoubtedly pioneers in their field, pushing the boundaries of conventional building methods. Their vision was to create a home that was not only functional but also visually striking, a goal they achieved with the Duplex Sheath house.

Identification Characteristics

Recognizing a Duplex Sheath house is relatively straightforward due to its unique features. This two-storey detached house boasts a rendered semi-circular roof with ribs at regular intervals, giving it a distinctive silhouette. The external walls are fully rendered, providing a smooth, uniform appearance. Additionally, the house features an external brick chimney breast at the gable ends, a flat canopy over the front door, and dormer windows, all contributing to its unique charm.

Alternative Names

The Duplex Sheath house is sometimes simply referred to as “Duplex,” a nod to its innovative design and construction methodology.

Construction Details

Understanding the construction details of the Duplex Sheath house is crucial for potential buyers and investors. This knowledge not only helps in identifying the property but also in assessing its condition and potential risks.

Substructure

The substructure of the Duplex Sheath house consists of concrete pads below stanchions, providing a stable foundation. The concrete slab is thickened around the perimeter, and a damp-proof course (DPC) is included to prevent moisture ingress.

Main Frame

The main frame is a complex assembly of steel components, including eight RSJ single-storey stanchions, two double RSC perimeter beams forming an I-shape, and two RSJ floor support beams. The roof structure comprises eleven semi-circular double RSA roof ribs, each forming a T-shape, a central RSJ ridge beam, and steel rod bracings. This robust steel framework ensures the structural integrity of the house.

External Walls

The external walls are constructed using rendered metal lathing cavity walls, providing both strength and insulation. This method of construction was innovative for its time, offering a durable and weather-resistant exterior.

Ground and First Floors

The ground floor is made of concrete, while the first floor consists of PRC slabs supported by steel beams. This combination of materials ensures a solid and stable flooring system throughout the house.

Roof

The roof of the Duplex Sheath house is particularly distinctive, featuring ridge tiles that form ribs over the frame. The roof is covered with bitumen-coated material and render on wire mesh, providing excellent weather resistance and durability.

Typical Characteristics and Hazards

While the Duplex Sheath house is a remarkable piece of architecture, it is essential to be aware of its typical characteristics and potential hazards.

Structural Integrity

The steel frame provides excellent structural integrity, but it is crucial to inspect for any signs of corrosion or damage to the protective coating. Over time, exposure to moisture and environmental factors can lead to rust, compromising the strength of the steel components.

Moisture Ingress

Despite the inclusion of a damp-proof course, moisture ingress can still be a concern, particularly in older properties. Inspecting the condition of the DPC and looking for signs of dampness in the walls and floors is essential.

Roof Condition

The semi-circular roof, while visually striking, requires regular maintenance to ensure its integrity. Inspecting the bitumen-coated material and render for any signs of wear or damage is crucial to prevent leaks and water damage.

External Walls

The rendered metal lathing cavity walls provide good insulation, but it is essential to check for any cracks or damage to the render. Cracks can allow moisture to penetrate the walls, leading to potential structural issues.

Defective Premises Act

The Duplex Sheath house is not classed as defective under the Defective Premises Act. However, given its age and unique construction, it is essential to conduct thorough inspections and assessments to ensure its condition and safety.

Inspection and Assessment Guide

For surveyors and potential buyers, conducting a thorough inspection of a Duplex Sheath house is crucial. Here are some key areas to focus on:

Steel Frame

Inspect the steel frame for any signs of corrosion or damage. Pay particular attention to the protective coating, as any deterioration can lead to rust and compromise the structural integrity.

Damp-Proof Course

Check the condition of the damp-proof course and look for any signs of moisture ingress in the walls and floors. Dampness can lead to structural issues and affect the overall condition of the property.

Roof

Examine the roof for any signs of wear or damage to the bitumen-coated material and render. Ensure that the ridge tiles and ribs are in good condition and that there are no leaks or water damage.

External Walls

Inspect the rendered metal lathing cavity walls for any cracks or damage. Ensure that the render is in good condition and that there are no signs of moisture penetration.

Floors

Check the condition of the concrete ground floor and the PRC slabs on the first floor. Look for any signs of cracking or damage that could affect the stability of the flooring system.

Typical Defects

While the Duplex Sheath house is a robust and well-designed property, it is essential to be aware of some typical defects that may arise over time.

Corrosion of Steel Components

One of the most common issues with steel-framed houses is the corrosion of steel components. Regular inspections and maintenance of the protective coating can help prevent this issue.

Moisture Ingress

As mentioned earlier, moisture ingress can be a concern, particularly in older properties. Ensuring that the damp-proof course is in good condition and addressing any signs of dampness promptly can help mitigate this risk.

Roof Leaks

The semi-circular roof, while distinctive, can be prone to leaks if not properly maintained. Regular inspections and maintenance of the bitumen-coated material and render can help prevent water damage.

Cracks in Render

Cracks in the rendered metal lathing cavity walls can allow moisture to penetrate the walls, leading to potential structural issues. Regular inspections and prompt repairs can help maintain the integrity of the walls.

Conclusion

The Duplex Sheath house is a unique and historically significant property, offering a blend of innovative design and robust construction. For potential buyers and investors, understanding the key characteristics, potential hazards, and typical defects of this property type is crucial. Conducting thorough inspections and regular maintenance can help ensure the longevity and safety of the Duplex Sheath house.

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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