Understanding the Craftcast House

The Craftcast house, a unique property type, holds a significant place in the UK’s architectural history. Designed by Craftcast Ltd and manufactured by Jones & Harvey, these properties were primarily built in the 1940s. With only 200 units constructed, they are relatively rare, making them a fascinating subject for home buyers and investors alike. These houses, also known as Jones & Harvey houses, are typically found in suburban areas and are characterized by their distinctive construction features.

Historical Context and Manufacturing Details

Period and Location

Craftcast houses emerged in the post-World War II era, a time when the UK faced a severe housing shortage. The government and private sector collaborated to develop quick and cost-effective housing solutions. The Craftcast house was one such innovation, designed to meet the urgent need for affordable homes. These properties are predominantly located in suburban areas, where land was more readily available for new developments.

Manufacturers and Designers

Jones & Harvey, a well-known construction firm of the time, were the primary manufacturers of Craftcast houses. The design was the brainchild of Craftcast Ltd, a company specializing in innovative building techniques. Together, they created a property type that was both functional and aesthetically pleasing, catering to the needs of the growing middle class.

Typical Characteristics of Craftcast Houses

Architectural Features

Craftcast houses are easily identifiable by their unique architectural features. They come in two main forms: bungalows and two-storey detached or semi-detached houses. One of the most distinctive features is the flat roof covered with asphalt, which includes box gutters cast into the top of the flat roof slab. The external walls are either rendered or coated in cement paint, with thickened sections at the quoins to form mock columns. The impression of formwork is often visible on the surface of the external walls, adding to their distinctive appearance. Additionally, these houses feature PRC (Precast Reinforced Concrete) window sills.

Construction Details

The construction of Craftcast houses involves several key elements:

• Substructure: The foundation consists of a concrete slab thickened below external and separating walls, with a damp-proof membrane (DPM) to prevent moisture ingress.
• External Walls: The external walls are made of 7-inch reinforced concrete (RC) with vertical and horizontal reinforcement. They also include 1.5-inch woodwool slabs for insulation.
• Separating Wall: The separating walls between properties are 8 inches thick and made of reinforced concrete.
• Partitions: Internal partitions are constructed from 4-inch concrete.
• Ground Floor: The ground floor features tongue-and-groove (T&G) wooden blocks set in bitumen on a concrete base.
• First Floor: The first floor comprises T&G wooden blocks on a 6-inch RC slab, which bears directly on the external walls and partitions, with additional woodwool slabs for insulation.
• Staircase: The staircase is made of reinforced concrete.
• Roof: The roof is a 5-6 inch RC cambered slab with overhanging eaves and RC dentils beneath the eaves overhang. It also includes a cast-in box gutter and is covered with asphalt.

Variants

There are several variants of Craftcast houses, which include:

• External walls made of 6.5 or 7-inch dense or lightweight (Cheecol) reinforced concrete.
• External walls made of 8-inch no-fines reinforced concrete.
• Internal walls made of 4.5-inch reinforced concrete.
• Linings made of fibreboard.

Typical Hazards and Risks

Structural Concerns

One of the primary concerns with Craftcast houses is the durability of the reinforced concrete. Over time, the steel reinforcement within the concrete can corrode, leading to structural weaknesses. This is particularly problematic in areas with high levels of moisture or where the concrete has been exposed to the elements.

Moisture Ingress

The flat roof design, while innovative at the time, can be prone to water ingress if not properly maintained. The asphalt covering and box gutters need regular inspection and maintenance to prevent leaks and water damage.

Thermal Insulation

The original woodwool slabs used for insulation may not meet modern thermal efficiency standards. This can result in higher heating costs and a less comfortable living environment.

Asbestos

Given the era in which these houses were built, there is a possibility that asbestos-containing materials were used in their construction. Asbestos poses significant health risks if disturbed, so it is crucial to have a professional survey conducted to identify and manage any asbestos present.

Legal Considerations

Defective Premises Act

Craftcast houses are not specifically listed as defective under the Defective Premises Act. However, given their age and the potential for structural issues, it is essential to have a thorough survey conducted before purchase. This will help identify any defects and provide a clear understanding of the property’s condition.

Inspection Guide for Surveyors

Preliminary Assessment

When inspecting a Craftcast house, start with a preliminary assessment of the property’s overall condition. Look for visible signs of wear and tear, such as cracks in the walls, sagging roofs, or water stains. Note any areas that may require further investigation.

Detailed Structural Inspection

Roof

• Flat Roof: Inspect the asphalt covering for signs of wear, cracks, or blisters. Check the box gutters for blockages and ensure they are properly sealed.
• Eaves and Dentils: Examine the overhanging eaves and RC dentils for any signs of damage or deterioration.

Walls

• External Walls: Look for cracks or spalling in the reinforced concrete. Check for signs of moisture ingress, such as damp patches or efflorescence.
• Separating Walls: Inspect the 8-inch RC separating walls for structural integrity. Look for any signs of movement or cracking.

Floors

• Ground Floor: Check the condition of the T&G wooden blocks and the bitumen layer. Look for signs of moisture damage or warping.
• First Floor: Inspect the RC slab and T&G wooden blocks for any signs of structural issues or damage.

Internal Partitions

• Concrete Partitions: Examine the 4-inch concrete partitions for cracks or signs of movement.

Staircase

• RC Staircase: Check the reinforced concrete staircase for any signs of wear or damage. Ensure it is securely anchored and free from cracks.

Moisture and Insulation

• Damp-Proof Membrane: Verify the presence and condition of the DPM in the substructure. Look for signs of rising damp or moisture ingress.
• Insulation: Assess the condition of the woodwool slabs and any other insulation materials. Consider upgrading to modern insulation if necessary.

Asbestos Survey

Given the potential presence of asbestos, it is crucial to conduct a thorough asbestos survey. Identify any asbestos-containing materials and develop a management plan to ensure they are safely handled and removed if necessary.

Common Defects in Craftcast Houses

Corrosion of Steel Reinforcement

One of the most common defects in Craftcast houses is the corrosion of the steel reinforcement within the concrete. This can lead to spalling, cracking, and ultimately structural failure if not addressed. Regular inspections and maintenance are essential to identify and mitigate this issue.

Water Ingress and Damp

The flat roof design and box gutters can be prone to water ingress if not properly maintained. This can lead to damp issues, which can cause further structural damage and create an unhealthy living environment. Regular maintenance of the roof and gutters is crucial to prevent water ingress.

Thermal Efficiency

The original woodwool slabs used for insulation may not meet modern thermal efficiency standards. Upgrading the insulation can improve the property’s energy efficiency and reduce heating costs.

Asbestos

As previously mentioned, the potential presence of asbestos is a significant concern. It is essential to identify and manage any asbestos-containing materials to ensure the safety of the occupants.

Maintenance and Repair Recommendations

Regular Inspections

Conduct regular inspections of the property to identify any potential issues early. This includes checking the roof, walls, floors, and internal partitions for signs of wear or damage.

Roof Maintenance

Ensure the flat roof and box gutters are regularly maintained to prevent water ingress. This includes checking the asphalt covering for cracks or blisters and ensuring the gutters are free from blockages.

Structural Repairs

Address any signs of corrosion in the steel reinforcement promptly. This may involve repairing or replacing affected sections of concrete to ensure the structural integrity of the property.

Insulation Upgrades

Consider upgrading the insulation to modern standards to improve the property’s thermal efficiency. This can help reduce heating costs and create a more comfortable living environment.

Asbestos Management

If asbestos-containing materials are identified, develop a management plan to ensure they are safely handled and removed if necessary. This may involve hiring a professional asbestos removal company to carry out the work.

Conclusion

Craftcast houses, with their unique architectural features and historical significance, offer a fascinating opportunity for home buyers and investors. However, it is essential to be aware of the potential hazards and risks associated with these properties. Conducting a thorough survey and regular maintenance can help ensure the longevity and safety of a Craftcast 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.