Historical Context and Manufacturing

The Unit No-Fines house, a notable example of system-built properties, emerged in the UK between 1927 and the 1950s. This period saw a significant demand for affordable and quickly constructed housing solutions, driven by the need to address housing shortages post-World War I and II. The Unit No-Fines house was primarily manufactured by Unit Construction Co. Ltd and Wilson Lovatt and Sons Ltd, with the design also attributed to Unit Construction Co. Ltd. Approximately 4,350 of these houses were built, predominantly in semi-detached and terraced forms.

These houses are often referred to by various names, including Lovatt, No-Fines, UCO, Unit, Wilson Lovatt, and Wilson Lovatt 83. They are typically found in suburban areas across the UK, where rapid urban expansion required efficient and cost-effective housing solutions.

Key Characteristics and Construction Details

Identification Characteristics

Unit No-Fines houses are easily identifiable by their distinct architectural features:
– Structure: They are usually 2-storey semi-detached or terraced houses.
– Roof: These houses feature a medium pitch hipped or gable roof, covered with either clay or concrete tiles.
– External Walls: The external walls are rendered throughout, providing a uniform and somewhat austere appearance.

Construction Techniques

The construction of Unit No-Fines houses involves several unique techniques and materials, which were innovative at the time:

Substructure

• Footings: Concrete strip footings provide the foundational support.
• Underbuilding: Dense concrete underbuilding is used, along with a concrete slab and a damp-proof course (DPC).

External Walls

• Material: The external walls are constructed from 8-inch clinker no-fines reinforced concrete (RC), with 1/2-inch bar reinforcement at ground floor window heads and below openings, extending up to 18 inches beyond the reveals.
• Rendering: The walls are rendered to provide a weather-resistant finish.

Internal Walls and Partitions

• Separating Wall: An 8-inch foamed slag concrete wall separates the units.
• Partitions: Clinker concrete blocks are used for internal partitions, tied to the external and separating walls with iron hoops grouted into cored recesses. Dense concrete blocks are used below the DPC level.

Floors

• Ground Floor: Constructed from concrete.
• First Floor: Timber boarding on timber joists.

Roof

• Structure: Timber trusses support the roof, which is covered with concrete tiles.

Chimney Breast

• Material: Constructed from foamed slag concrete.

Variants

There are notable differences between pre-war and post-war Unit No-Fines houses:

Pre-War Houses

• First Floor: Utilizes lightweight steel joists.
• Roof: Constructed with lightweight steel trusses.

Post-War Houses

• External Walls: Made from foamed slag concrete.
• Separating Wall: Constructed from foamed slag no-fines concrete.
• Partitions: Made from clinker block.
• Roof: Covered with clay tiles.
• Chimney Breast: Constructed from brick.

Typical Hazards and Risks

Structural Issues

Unit No-Fines houses, like many system-built properties, are prone to specific structural issues:

Pre-War Houses

• Cracking: Clinker concrete above communal walkways and around door and window openings is susceptible to cracking.

Post-War Houses

• Cracking in External Walls: Foamed slag concrete external walls often exhibit horizontal cracking, coinciding with reinforcement.
• Material Weakness: Foamed slag concrete is friable and weak, although generally sufficient for use in 2-storey houses.

Material Concerns

• Unstable Aggregates: The aggregate used in the construction may contain unstable fractions of unburnt coal, which can compromise the structural integrity over time.

Defective Premises Act Considerations

The Unit No-Fines house is not universally classified as defective under the Defective Premises Act. However, the specific structural issues and material weaknesses associated with these properties can lead to significant maintenance and repair challenges. It is crucial for potential buyers and investors to conduct thorough inspections and seek expert advice to understand the condition and potential risks of these properties.

Inspection Guide for Surveyors

When inspecting a Unit No-Fines house, surveyors should pay close attention to the following areas:

External Walls

• Cracking: Look for horizontal and vertical cracks, particularly around door and window openings.
• Rendering: Check the condition of the rendering for signs of deterioration or damage.

Internal Walls and Partitions

• Separating Wall: Inspect for cracks and signs of movement in the foamed slag concrete.
• Partitions: Examine the clinker concrete blocks for stability and signs of wear.

Floors

• Ground Floor: Check for any signs of subsidence or unevenness in the concrete floor.
• First Floor: Inspect the timber boarding and joists for signs of rot or damage.

Roof

• Trusses: Ensure the timber trusses are in good condition and free from rot or insect damage.
• Tiles: Check the condition of the clay or concrete tiles for any signs of damage or wear.

Chimney Breast

• Material: Inspect the foamed slag concrete or brick chimney breast for structural integrity and signs of cracking.

Common Defects in Unit No-Fines Houses

Cracking

• External Walls: Horizontal and vertical cracking in the foamed slag concrete.
• Internal Walls: Cracks in the separating and partition walls.

Material Degradation

• Foamed Slag Concrete: Friable and weak, prone to deterioration over time.
• Clinker Concrete: Susceptible to cracking and instability.

Roof Issues

• Timber Trusses: Potential for rot and insect damage.
• Tiles: Wear and damage to clay or concrete tiles.

Damp and Moisture

• DPC: Check for effectiveness of the damp-proof course.
• Rendering: Inspect for signs of moisture penetration through the rendering.

Conclusion

The Unit No-Fines house represents a significant chapter in the history of UK housing, offering a unique blend of architectural and construction techniques. While these properties can present certain challenges, they also offer potential for those willing to invest in their maintenance and repair.

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.