Historical Context and Background

The Occident house, a unique and historically significant property type, was manufactured by the British Occident Concrete Construction Co. Ltd. Designed by John Bland, these houses were built during the period of 1926-27. Only 30 of these properties were constructed, making them a rare find in the UK property market. Often referred to as “Wheatley” houses, these properties are typically located in suburban areas, reflecting the architectural and construction trends of the early 20th century.

Identification Characteristics

Occident houses are easily identifiable by their distinct architectural features. These are 2-storey semi-detached houses with a medium pitch hipped roof covered with clay tiles. The external walls of the ground floor are made of storey-height precast concrete (PC) panels, painted to the first-floor level and covered with tile hanging above. A notable feature is the bay window on the front elevation, which includes spandrel panels of rendered blockwork. Additionally, the door is framed with a cast concrete architrave, adding to the unique aesthetic of these homes.

Construction Details

Substructure

The substructure of Occident houses consists of concrete strip footings, providing a solid foundation for the property. This type of footing is typical for houses built during this period and offers stability and durability.

External Walls

The external walls are constructed using full-width storey-height 7½” PC panels. These panels incorporate door and window frames on the ground floor, set on a mortar bed. The outer leaf is made of 2″ exposed dense aggregate, followed by a 3½” cavity filled with loose clinker, and a 2″ clinker concrete inner leaf finished with a skim coat of plaster. The first floor follows a similar construction method but features a 2″ clinker concrete outer leaf covered with tile hanging. Steel interlocking lugs link the edge steel reinforcement, ensuring structural integrity.

Separating Wall

The separating wall between the semi-detached units is also constructed using full-width storey-height 7½” clinker concrete PC panels. These panels incorporate flues and are finished with a skim coat of plaster, providing both structural support and fire resistance.

Partitions

Internal partitions are made of storey-height room-sized clinker concrete PC panels. These panels are 4½” thick on the ground floor and 2″ thick on the first floor, both finished with a skim coat of plaster. This construction method ensures robust internal walls that contribute to the overall stability of the house.

Floors

The ground floor features suspended timber joists, a common construction method during the period. The first floor also uses timber joists, providing a consistent structural framework throughout the house.

Roof

The roof is constructed using timber joists and purlins, covered with plain tiles. This traditional roofing method not only adds to the aesthetic appeal of the house but also ensures durability and weather resistance.

Typical Hazards and Risks

Structural Integrity

One of the primary concerns with Occident houses is the potential for structural issues due to the age of the properties. Over time, the concrete panels and steel reinforcements may deteriorate, leading to potential structural weaknesses. It is crucial to conduct a thorough inspection to assess the condition of these elements.

Corrosion of Steel Reinforcement

The steel reinforcement within the concrete panels is susceptible to corrosion, especially if the concrete has been exposed to moisture over the years. Corrosion can lead to spalling, where the concrete surface breaks away, exposing the steel and further accelerating the deterioration process.

Carbonation

Carbonation is a chemical reaction that occurs when carbon dioxide from the air penetrates the concrete and reacts with calcium hydroxide to form calcium carbonate. This process can reduce the alkalinity of the concrete, leading to the corrosion of the steel reinforcement. It is essential to measure the carbonation depth to assess the risk of corrosion.

Thermal Insulation

The construction methods used in Occident houses may not meet modern thermal insulation standards. The clinker fill in the cavity walls provides some insulation, but additional measures may be required to improve energy efficiency and reduce heating costs.

Damp and Moisture Ingress

Due to the age and construction methods of Occident houses, there is a risk of damp and moisture ingress. This can lead to issues such as mould growth, wood rot, and damage to internal finishes. It is important to inspect for signs of dampness and address any issues promptly.

Defective Premises Act

Occident houses are not specifically classed as defective under the Defective Premises Act. However, due to their age and unique construction methods, they may present certain challenges that require careful consideration. It is essential to conduct a thorough survey to identify any potential defects and address them accordingly.

Inspection and Assessment Guide

Visual Inspection

Begin with a visual inspection of the property, focusing on the external walls, roof, and any visible structural elements. Look for signs of cracking, spalling, or other damage to the concrete panels. Check the condition of the roof tiles and timber elements for any signs of wear or damage.

Structural Assessment

Conduct a detailed structural assessment to evaluate the condition of the concrete panels and steel reinforcement. This may involve non-destructive testing methods such as ultrasonic testing or ground-penetrating radar to assess the integrity of the concrete and locate any areas of corrosion.

Carbonation Testing

Perform carbonation testing to measure the depth of carbonation in the concrete. This can be done using a phenolphthalein solution, which changes colour in the presence of alkaline concrete. A deeper carbonation depth indicates a higher risk of steel reinforcement corrosion.

Moisture Assessment

Check for signs of dampness and moisture ingress, both internally and externally. Use moisture meters to measure the moisture content of walls and floors. Inspect for any signs of mould growth, wood rot, or damage to internal finishes.

Thermal Imaging

Consider using thermal imaging to assess the thermal performance of the property. This can help identify areas of heat loss and potential insulation issues. Thermal imaging can also reveal hidden dampness or moisture ingress that may not be visible during a visual inspection.

Roof Inspection

Inspect the roof structure, including the timber joists and purlins, for any signs of damage or deterioration. Check the condition of the roof tiles and ensure they are securely fixed. Look for any signs of water ingress or damage to the roof covering.

Typical Defects and Maintenance

Cracking and Spalling

Cracking and spalling of the concrete panels are common defects in Occident houses. These issues can be caused by a variety of factors, including thermal movement, moisture ingress, and corrosion of the steel reinforcement. It is important to address these defects promptly to prevent further deterioration.

Corrosion of Steel Reinforcement

As mentioned earlier, the steel reinforcement within the concrete panels is susceptible to corrosion. Regular inspections and maintenance are essential to identify and address any areas of corrosion. This may involve removing and replacing damaged concrete, applying corrosion inhibitors, or using cathodic protection methods.

Damp and Moisture Ingress

Damp and moisture ingress can lead to a range of issues, including mould growth, wood rot, and damage to internal finishes. It is important to identify and address the source of moisture ingress, whether it is due to defective roofing, poor drainage, or other factors. Consider installing damp-proof courses or membranes to prevent moisture ingress.

Thermal Insulation

Improving the thermal insulation of Occident houses can help reduce heating costs and improve energy efficiency. This may involve adding insulation to the cavity walls, roof, and floors. Consider using modern insulation materials that meet current building regulations and standards.

Roof Maintenance

Regular roof maintenance is essential to ensure the longevity and performance of the roof structure. This includes inspecting and replacing damaged roof tiles, checking the condition of the timber joists and purlins, and ensuring proper drainage to prevent water ingress.

Conclusion

Occident houses, with their unique construction methods and historical significance, offer a distinctive option for home buyers and investors in the UK. However, due to their age and specific construction characteristics, these properties require careful consideration and thorough inspection. By understanding the typical hazards and risks associated with Occident houses, and following a detailed inspection and maintenance guide, 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.

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