When it comes to purchasing a property in the UK, understanding the intricacies of different construction types is crucial. One such property type that often piques the interest of home buyers and investors is the HDC house. Built in the 1960s by Housing Development & Construction Ltd, these homes are a significant part of the UK’s architectural history. This article delves into the essential aspects of HDC houses, from their construction details to potential hazards, and offers practical advice for inspecting these properties.

Historical Context and Manufacturers

The HDC house, also known as Housing Development & Construction or IDC, was a product of the post-war housing boom in the 1960s. During this period, there was a pressing need for affordable and quickly constructed homes to accommodate the growing population. Housing Development & Construction Ltd, in collaboration with Housing and Planning Consultants Ltd, rose to the challenge by designing and building approximately 600 of these homes.

These properties were primarily constructed as bungalows and two-storey semi-detached and terraced houses. They were designed to be cost-effective and efficient, utilizing system-built construction methods that were innovative for their time.

Identification Characteristics

Recognizing an HDC house is relatively straightforward once you know what to look for. Here are some key identification characteristics:

• Roof: Shallow pitch gable roof covered with bituminous felt or copper.
• External Walls: Eaves height PC (precast concrete) panels alternating with feature panels of horizontal timber boarding or asbestos cement sheets.
• Structure: The system was also used for flats, although these are less common.

These features make HDC houses distinctive and relatively easy to identify during a property inspection.

Construction Details

Understanding the construction details of HDC houses is essential for assessing their condition and potential risks. Here is a detailed breakdown of the typical construction elements:

Substructure

The substructure of HDC houses consists of concrete pads measuring 2’6″ x 2’6″ at the corners and 2’6″ x 5’6″ beneath the junction of separating and external walls. These pads are crucial for providing a stable foundation. One or two 1″ locating dowels are used, along with PRC (precast reinforced concrete) perimeter beams rebated at the corners to form half-lap joints. These beams are levelled on steel shims and mortar at the corners. A damp-proof membrane (DPM) and damp-proof course (DPC) are also included to prevent moisture ingress.

External Walls

The external walls are constructed using 2″ eaves height dished PC panels, thickened at the perimeter by a central vertical rib. These panels are located by 2 MS (mild steel) dowels at the top of the PRC perimeter beams. The walls also feature a PVC baffle and neoprene tube, timber framing lined with foil-backed plasterboard, and insulation between the frame studs. Eaves height timber frame panels are fixed to the PC panels with RSA (rolled steel angle) cleats, clad with horizontal timber boarding, and lined with foil-backed plasterboard.

Separating Wall

The separating wall consists of 6″ PC panels located in a rebate in the ground floor slab and lined with plasterboard. This design provides structural integrity and sound insulation between adjoining properties.

Partitions

Internal partitions are constructed using 2 1/4″ plasterboard sandwich partitions, which are lightweight and easy to install.

Floors

The ground floor is typically made of concrete, providing a solid and durable base. The first floor consists of plywood on timber joists, supported by RSJ (rolled steel joist) floor beams and RS hollow box sections. These beams are supported by RS hollow box stanchions and timber wall plates at the separating wall.

Ceilings

Ceilings are constructed using plasterboard, which is a common and cost-effective material.

Roof

The roof structure includes four prefabricated plywood box beams bolted with MS plates to each truss ceiling tie. The roof is covered with bituminous felt, and integral guttering is included to manage rainwater.

Variants

Some HDC houses feature a piled substructure, which provides additional stability in areas with poor soil conditions.

Typical Hazards and Risks

While HDC houses were innovative for their time, they are not without their potential hazards and risks. Here are some common issues to be aware of:

Corrosion

One of the most significant risks associated with HDC houses is corrosion. The variable depth of cover to reinforcement in PC panels can lead to corrosion of stirrups. Additionally, carbonation to the inside face of external wall panels can cause corrosion of reinforcement. Loose steel channel connecting bolts and corrosion of foil-backed plasterboard are also common issues.

Asbestos

Asbestos cement sheets were commonly used in the construction of HDC houses. Asbestos is a hazardous material that can pose serious health risks if disturbed. It is essential to have a professional asbestos survey conducted before any renovation or demolition work.

Structural Integrity

The structural integrity of HDC houses can be compromised over time due to various factors, including corrosion and settlement. It is crucial to have a thorough structural survey conducted to identify any potential issues.

Moisture Ingress

Moisture ingress can be a problem in HDC houses, particularly if the DPM and DPC are compromised. This can lead to dampness and mould growth, which can affect the health of the occupants and the structural integrity of the property.

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 HDC houses were built to meet the standards of their time, some may now be considered defective under this Act due to the issues mentioned above. It is essential to have a professional survey conducted to assess the condition of the property and identify any potential defects.

Inspection Tips for Surveyors

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

External Walls

Check for signs of corrosion in the PC panels and reinforcement. Look for loose steel channel connecting bolts and corrosion of foil-backed plasterboard. Inspect the timber boarding and asbestos cement sheets for any signs of damage or deterioration.

Roof

Inspect the roof for signs of wear and tear, particularly the bituminous felt or copper covering. Check the integral guttering for blockages or damage.

Substructure

Examine the concrete pads and PRC perimeter beams for any signs of settlement or movement. Check the DPM and DPC for any signs of compromise.

Internal Walls and Partitions

Inspect the plasterboard partitions for any signs of damage or moisture ingress. Check the separating wall for any signs of movement or cracking.

Floors

Examine the ground floor concrete for any signs of cracking or settlement. Check the first floor plywood and timber joists for any signs of damage or deterioration.

Ceilings

Inspect the plasterboard ceilings for any signs of sagging or moisture ingress.

Asbestos

If asbestos cement sheets are present, ensure that a professional asbestos survey is conducted to assess the condition and potential risks.

Conclusion

HDC houses are a significant part of the UK’s architectural history, offering a unique blend of innovation and practicality. However, they are not without their potential hazards and risks. Understanding the construction details and common issues associated with these properties is crucial for home buyers and investors. By conducting a thorough inspection and addressing any potential defects, you can ensure that your investment is safe and sound.

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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