Historical Context and Manufacturing Background

The Braithwaite house, also known as the Unit Frame house, is a unique example of post-war British architecture. Manufactured by Braithwaite & Co. Ltd and designed by F R S Yorke, these properties were constructed in 1945. Only two of these houses were built, making them a rare find in the UK property market. Typically, these houses are found in semi-detached and terraced forms, featuring a distinctive flat roof covered with bituminous felt.

Identification Characteristics

Recognising a Braithwaite house is relatively straightforward due to its unique construction features. These houses are two-storey structures, often semi-detached or terraced. The external walls are clad with storey-height fluted asbestos cement sheets, either throughout or on the front and rear walls, with the flank wall made of brick up to the first-floor level and fluted asbestos cement sheets above. This distinctive cladding is a key identifier for these properties.

Construction Details

Substructure

The foundation of a Braithwaite house consists of a concrete trench fill foundation incorporating a concrete slab. A damp-proof course (DPC) is also included to prevent moisture from rising through the structure.

Frame

The main frame of the house is constructed from eaves-height ladder-like pre-stressed concrete (PSC) steel frames bolted together with brackets. This frame supports two PSC floor and roof support perimeter beams, as well as PSC section floor and roof support beams. The entire frame is coated with graphite paint for protection.

External Walls

The front and rear walls are clad with fluted asbestos cement sheets, while the flank wall is clad with brick up to the first-floor level and fluted asbestos cement sheets above. The walls are lined with wallboard and insulated with mineral fibre between the frame studs.

Separating Wall

The separating wall between properties is made of aerated concrete block cavity wall, providing both structural integrity and sound insulation.

Partitions

Internal partitions are constructed from steel framing lined with fibreboard, offering a lightweight yet sturdy solution for dividing internal spaces.

Floors

The ground floor consists of blockboard panels on concrete, while the first floor features blockboard panels on timber bearers.

Ceilings

Ceilings are made from fibreboard, providing a smooth and uniform finish.

Roof

The roof is constructed from aerated concrete slabs covered with bituminous felt, offering durability and weather resistance.

Typical Hazards and Risks

Asbestos

One of the primary concerns with Braithwaite houses is the presence of asbestos in the external cladding. Asbestos was commonly used in construction during the mid-20th century due to its fire-resistant properties. However, it is now known to pose significant health risks if disturbed. It is crucial to have a professional asbestos survey conducted before any renovation or demolition work.

Structural Integrity

The steel frame of the Braithwaite house, while robust, can be susceptible to corrosion over time, especially if the protective graphite paint has deteriorated. Regular inspections are necessary to ensure the frame remains in good condition.

Insulation

The mineral fibre insulation used in the walls may not meet modern energy efficiency standards. Upgrading the insulation can improve the property’s thermal performance and reduce energy bills.

Damp and Moisture

The concrete slab foundation and damp-proof course are designed to prevent moisture ingress. However, over time, these elements can degrade, leading to potential damp issues. Regular maintenance and inspections are essential to address any signs of dampness promptly.

Defective Premises Act

The Braithwaite house is not classified as defective under the Defective Premises Act. However, due to its age and unique construction, it is essential to conduct thorough inspections and maintenance to ensure it remains safe and habitable.

Inspection Guide for Surveyors

External Inspection

1. Roof: Check the condition of the bituminous felt covering. Look for signs of wear, cracks, or leaks. Inspect the aerated concrete slabs for any damage or deterioration.
2. Walls: Examine the fluted asbestos cement sheets for any cracks, damage, or signs of asbestos exposure. Inspect the brickwork on the flank wall for any signs of movement or deterioration.
3. Foundation: Check for any signs of subsidence or movement in the concrete trench fill foundation. Look for cracks or gaps in the concrete slab.

Internal Inspection

1. Frame: Inspect the steel frame for any signs of corrosion or damage. Pay particular attention to the brackets and joints where the frames are bolted together.
2. Walls: Check the internal wallboard lining for any signs of dampness or damage. Inspect the mineral fibre insulation for any signs of degradation or moisture ingress.
3. Floors: Examine the blockboard panels on the ground and first floors for any signs of wear or damage. Check the timber bearers for any signs of rot or insect infestation.
4. Ceilings: Inspect the fibreboard ceilings for any signs of sagging, damage, or moisture ingress.

Additional Considerations

1. Asbestos Survey: Given the presence of asbestos in the external cladding, it is essential to conduct a professional asbestos survey before any renovation or demolition work.
2. Energy Efficiency: Consider upgrading the insulation to improve the property’s thermal performance and reduce energy bills.
3. Damp and Moisture: Regularly inspect the damp-proof course and concrete slab foundation for any signs of moisture ingress. Address any issues promptly to prevent further damage.

Typical Defects and Maintenance Tips

Asbestos Degradation

Asbestos cement sheets can degrade over time, especially if exposed to the elements. Regular inspections are necessary to identify any signs of damage or deterioration. If asbestos is found to be in poor condition, it is essential to have it removed by a licensed professional.

Corrosion of Steel Frame

The steel frame of the Braithwaite house can be susceptible to corrosion, especially if the protective graphite paint has deteriorated. Regular inspections and maintenance are necessary to ensure the frame remains in good condition. If corrosion is identified, it may be necessary to treat the affected areas and reapply protective coatings.

Insulation Upgrades

The mineral fibre insulation used in the walls may not meet modern energy efficiency standards. Upgrading the insulation can improve the property’s thermal performance and reduce energy bills. Consider using modern insulation materials that offer better thermal performance and are more environmentally friendly.

Damp and Moisture Management

The concrete slab foundation and damp-proof course are designed to prevent moisture ingress. However, over time, these elements can degrade, leading to potential damp issues. Regular maintenance and inspections are essential to address any signs of dampness promptly. Consider installing additional damp-proofing measures if necessary.

Roof Maintenance

The bituminous felt covering on the roof can degrade over time, leading to potential leaks and water ingress. Regular inspections and maintenance are necessary to ensure the roof remains in good condition. If any damage is identified, it may be necessary to repair or replace the bituminous felt covering.

Variants and Modifications

External Cladding

Some Braithwaite houses may have external walls clad with fluted asbestos cement sheets throughout, rather than just on the front and rear walls. This variant offers a more uniform appearance but still requires regular inspections and maintenance to address any potential asbestos-related issues.

Internal Linings

In some cases, Braithwaite houses may feature cellular plywood linings, partitions, and ceiling panels instead of the standard fibreboard. These materials offer a different aesthetic and may require different maintenance approaches.

Conclusion

The Braithwaite house is a unique and historically significant property type in the UK. While it offers a distinctive architectural style and robust construction, it also presents certain challenges and risks that must be carefully managed. Regular inspections and maintenance are essential to ensure the property remains safe and habitable. By understanding the typical characteristics, hazards, and maintenance requirements of Braithwaite houses, home buyers and investors can make informed decisions and safeguard their 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.