Understanding the Firmcrete House

The Firmcrete house, a notable example of system-built properties, emerged in the 1960s as a response to the post-war housing shortage in the UK. Manufactured by Firmcrete (London) Ltd, these properties were designed to be cost-effective and quick to construct. Approximately 2,000 Firmcrete houses were built during this period, primarily in urban and suburban areas. These homes are typically two-storey structures, identifiable by their flat roofs covered with bituminous felt and a combination of timber frame panels and tile hanging on the external walls.

Historical Context and Manufacturing Details

Period of Construction

Firmcrete houses were predominantly constructed in the 1960s, a decade marked by a significant demand for affordable housing solutions. The rapid urbanisation and population growth necessitated innovative construction methods that could deliver homes quickly and efficiently.

Manufacturer and Designer

Firmcrete (London) Ltd was the primary manufacturer of these houses. While specific details about the designers are scarce, the architectural style and construction techniques reflect the broader trends of the era, focusing on functionality and cost-effectiveness.

Typical Locations

These properties are commonly found in urban and suburban areas across the UK. They were part of large-scale housing developments aimed at providing affordable homes for the growing population.

Characteristics and Construction Details

Identification Characteristics

Firmcrete houses are easily identifiable by their distinct architectural features:
– Two-storey structure: These homes typically have two levels.
– Flat roof: The roofs are flat and covered with bituminous felt.
– External walls: The front and rear walls are made of timber frame panels clad with plywood up to the first-floor level, with tile hanging above. The flank walls are constructed from brick.

Construction Details

Substructure

The substructure of Firmcrete houses consists of concrete footings and a concrete slab, providing a stable foundation for the building.

External Walls

The front and rear external walls are constructed using storey-height timber frame panels. These panels are clad with plywood up to the first-floor level, with tile hanging backed by building paper above. The walls are lined with plasterboard on the inside, and insulation is placed between the frame studs. The flank walls are made of a 9-inch cavity wall comprising two leaves of 2-inch chemically impregnated cement-bonded chipboard slabs (known as Firmcrete slabs), with the cavity filled with reinforced concrete (RC).

Separating Wall

The separating wall between properties is a 9-inch cavity wall made of two leaves of 2-inch Firmcrete slabs, infilled with reinforced concrete.

Partitions

Internal partitions are constructed using 2 1/4-inch Firmcrete slabs.

Floors

The ground floor is made of concrete, while the first floor consists of timber boarding on timber joists.

Roof

The roof structure includes timber joists, 2-inch Firmcrete slabs, insulation, and bituminous felt. An internal gutter system is also present.

Variants

Some variants of the Firmcrete house feature flank walls that are rendered throughout, rather than having a combination of brick and render.

Typical Hazards and Risks

Structural Concerns

One of the primary concerns with Firmcrete houses is the potential for structural issues, particularly related to the reinforced concrete elements. Over time, the concrete can deteriorate due to carbonation and corrosion of the steel reinforcement. This can lead to cracking, spalling, and a reduction in the structural integrity of the building.

Moisture Ingress

The flat roofs covered with bituminous felt are prone to water ingress, especially if the roofing material has not been adequately maintained. This can lead to dampness and mould growth within the property, affecting both the structural elements and the indoor air quality.

Insulation and Energy Efficiency

The insulation used in Firmcrete houses may not meet modern standards, leading to poor energy efficiency. This can result in higher heating costs and a less comfortable living environment.

Asbestos

Given the period of construction, there is a possibility that asbestos-containing materials were used in some elements of the building. Asbestos poses significant health risks if disturbed, so it is crucial to have a professional survey conducted to identify and manage any asbestos-containing materials.

Defective Premises Act and Firmcrete Houses

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 Firmcrete houses were not specifically listed as defective under this Act, the potential structural issues and other hazards mentioned earlier could render a property defective if they significantly affect its safety and habitability.

Inspection and Assessment Guide for Surveyors

Preliminary Inspection

When inspecting a Firmcrete house, start with a thorough visual inspection of the exterior and interior. Look for signs of structural damage, such as cracks in the walls, spalling concrete, and any evidence of water ingress.

Detailed Structural Assessment

For a more detailed assessment, refer to the following resources:
– Corrosion of steel in concrete (BRE Digest 444, Pts 1–3)
– Repair and maintenance of reinforced concrete (BR 254)
– Carbonation depths in structural-quality concrete (BR 19)

These documents provide guidance on assessing the durability of reinforced concrete and identifying potential issues.

Roof Inspection

Inspect the flat roof for signs of wear and tear, such as cracks, blisters, or areas where the bituminous felt has lifted. Check the internal gutter system for blockages and signs of water ingress.

Insulation and Energy Efficiency

Assess the insulation in the walls and roof. Consider recommending upgrades to improve the property’s energy efficiency, such as adding modern insulation materials or installing double-glazed windows.

Asbestos Survey

Given the potential presence of asbestos, it is advisable to conduct an asbestos survey. This should be carried out by a qualified professional who can identify and manage any asbestos-containing materials safely.

Common Defects in Firmcrete Houses

Structural Defects

• Cracking and Spalling: Look for cracks in the concrete elements and areas where the concrete has spalled, exposing the steel reinforcement.
• Corrosion of Steel Reinforcement: Check for signs of rust staining on the concrete surfaces, which may indicate corrosion of the steel reinforcement.

Moisture-Related Issues

• Dampness and Mould: Inspect for signs of dampness and mould, particularly in areas where water ingress is likely, such as around windows, doors, and the roof.
• Roof Leaks: Check the flat roof for leaks and ensure that the bituminous felt is in good condition.

Insulation and Energy Efficiency

• Poor Insulation: Assess the effectiveness of the existing insulation and recommend upgrades if necessary.
• Single-Glazed Windows: If the property has single-glazed windows, consider recommending the installation of double-glazed units to improve energy efficiency.

Asbestos

• Asbestos-Containing Materials: Identify any materials that may contain asbestos and ensure they are managed safely.

Maintenance and Repair Recommendations

Structural Repairs

• Concrete Repairs: Address any structural defects in the concrete elements by repairing cracks and spalling. This may involve removing damaged concrete, treating the steel reinforcement, and applying a suitable repair mortar.
• Corrosion Protection: Apply corrosion inhibitors or protective coatings to the steel reinforcement to prevent further corrosion.

Roof Maintenance

• Roof Repairs: Repair any damage to the bituminous felt and ensure that the internal gutter system is functioning correctly.
• Regular Inspections: Schedule regular roof inspections to identify and address any issues before they become significant problems.

Insulation Upgrades

• Wall Insulation: Consider adding modern insulation materials to the walls to improve energy efficiency.
• Roof Insulation: Upgrade the roof insulation to reduce heat loss and improve the property’s overall energy performance.

Asbestos Management

• Asbestos Removal: If asbestos-containing materials are identified, have them removed by a qualified professional.
• Asbestos Management Plan: Develop an asbestos management plan to ensure that any remaining asbestos-containing materials are managed safely.

Conclusion

Firmcrete houses, with their unique construction and historical significance, offer both opportunities and challenges for home buyers and investors. Understanding the typical characteristics, potential hazards, and common defects associated with these properties is crucial for making informed decisions. By conducting thorough inspections and addressing any issues promptly, you can ensure that a Firmcrete house remains a safe and comfortable home 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.

---