Historical Context and Manufacturing

The BRS Type 4 house, also known simply as the BRS, is a unique example of post-war British architecture. Designed by the Building Research Station (BRS), these homes were constructed between 1953 and 1956. Only 60 of these properties were built, making them a rare find in today’s housing market. Typically, these houses are located in suburban areas, often in regions that experienced significant housing shortages following World War II.

The BRS Type 4 houses were part of a broader initiative to address the urgent need for housing in the post-war period. The Building Research Station, a government body, was responsible for the design and construction of these homes. The aim was to create affordable, quickly-constructed housing using innovative building techniques and materials.

Identification Characteristics

BRS Type 4 houses are easily identifiable by their distinct architectural features. These are two-storey detached and semi-detached houses with flat roofs covered in bituminous felt. The external walls are rendered throughout, giving them a uniform appearance. The design is utilitarian, reflecting the post-war emphasis on functionality and efficiency.

Key Features:

• Two-storey structure: Available in both detached and semi-detached forms.
• Flat roof: Covered with bituminous felt, a common material in mid-20th-century construction.
• Rendered external walls: Providing a consistent and easily recognizable exterior.

Typical Construction

Understanding the construction of BRS Type 4 houses is crucial for both buyers and investors. These homes were built using a variety of materials and techniques that were innovative at the time but may present challenges today.

Substructure

The substructure consists of concrete underbuilding and a concrete slab. This provides a solid foundation but can be prone to issues such as cracking and moisture ingress over time.

External Walls

The external walls are rendered and consist of:
1. 8″ no-fines concrete: A type of concrete that lacks fine aggregates, making it lighter but also more porous.
2. Timber frame panels lined with waffle plaster: Used as permanent shuttering.
3. Lightly reinforced dense RC (reinforced concrete) ring beams: Located at the first floor and eaves level.

Separating Wall

The separating wall between properties is made of 6″ no-fines concrete and timber frame panels lined with waffle plaster. This construction method aimed to provide adequate sound insulation and structural integrity.

Partitions

Internal partitions are made of cellular cardboard cored panels lined with plasterboard. While lightweight and easy to install, these partitions can be susceptible to damage and wear over time.

Floors

• Ground floor: Concrete, providing a durable and stable base.
• First floor: 7″ RC slab, offering robust support for the upper level.

Ceilings

Ceilings are constructed from ribbed plaster on timber frame panels, a method that provides both strength and aesthetic appeal.

Roof

The roof is a reinforced concrete slab covered with woodwool slabs and bituminous felt. This combination was intended to offer durability and weather resistance but can present maintenance challenges today.

Typical Hazards and Risks

While BRS Type 4 houses were innovative for their time, they come with a range of potential hazards and risks that buyers and investors should be aware of.

Deterioration of Render

The external render can deteriorate over time, leading to cracks and potential water ingress. Regular maintenance and repairs are essential to prevent further damage.

Spalling of RC Roof Slab Oversail

Spalling, or the breaking away of concrete, can occur in the RC roof slab oversail. This is often due to corrosion of the reinforcement within the concrete, which expands and causes the concrete to crack and break away.

Corrosion of Reinforcement in RC Roof Slab

The reinforcement within the RC roof slab can corrode over time, particularly if the concrete cover is inadequate. This can compromise the structural integrity of the roof.

Deterioration of Bituminous Felt Roof Cover

The bituminous felt roof cover can deteriorate due to exposure to the elements, leading to leaks and water damage. Regular inspections and maintenance are crucial to extend the lifespan of the roof.

Ponding of Water on Roof

Flat roofs are prone to ponding, where water accumulates and does not drain away. This can lead to leaks and structural damage if not addressed promptly.

Internal Condensation

Internal condensation can be a significant issue, particularly in homes with poor ventilation. This can lead to mould growth and damage to internal finishes.

Water Penetration Through External Walls and Roof

Water penetration can occur through both the external walls and the roof, leading to dampness and potential structural issues. Ensuring that the render and roof coverings are in good condition is essential to prevent this.

Inadequate Compaction of Dense Concrete in RC Beams

Inadequate compaction of dense concrete in RC beams can lead to voids and weaknesses within the concrete, compromising its strength and durability.

Inadequate Cover to Reinforcement in Dense RC Beams

If the concrete cover to the reinforcement in dense RC beams is inadequate, the reinforcement can corrode, leading to structural issues.

High Rates of Carbonation in Dense RC Spine Beams

Carbonation, a process where carbon dioxide penetrates the concrete and reacts with the calcium hydroxide to form calcium carbonate, can occur at high rates in dense RC spine beams. This can reduce the alkalinity of the concrete, leading to corrosion of the reinforcement.

Surface Corrosion of Reinforcement in Dense RC Spine Beams

Surface corrosion of the reinforcement in dense RC spine beams can occur, particularly if the concrete cover is inadequate or if there are high levels of cast-in chloride.

Low and Significant Levels of Cast-in Chloride

Chloride ions can be present in the concrete mix, either from the materials used or from external sources such as de-icing salts. High levels of chloride can lead to corrosion of the reinforcement.

Low Cement Content

Low cement content in the concrete mix can lead to weaker concrete, which is more susceptible to damage and deterioration.

Defective Premises Act

The BRS Type 4 house is not classed as defective under the Defective Premises Act. However, the various issues and potential hazards associated with these properties mean that buyers and investors should approach with caution. A thorough survey by a qualified professional is essential to identify any existing or potential issues and to assess the overall condition of the property.

Inspection Guide for Surveyors

When inspecting a BRS Type 4 house, surveyors should pay close attention to the following areas:

External Render

Check for signs of cracking, spalling, and general deterioration. Ensure that any repairs are carried out using appropriate materials and techniques to maintain the integrity of the render.

Roof

Inspect the bituminous felt roof cover for signs of wear and tear, and check for any ponding of water. Ensure that the RC roof slab is in good condition and that there are no signs of spalling or corrosion of the reinforcement.

Internal Walls and Partitions

Check for signs of internal condensation, mould growth, and water penetration. Ensure that the cellular cardboard cored partitions are in good condition and that there are no signs of damage or wear.

Floors

Inspect the concrete ground floor and the RC first floor slab for any signs of cracking or damage. Ensure that the floors are level and stable.

Ceilings

Check the ribbed plaster ceilings for any signs of cracking or damage. Ensure that the timber frame panels are in good condition and that there are no signs of deterioration.

Reinforced Concrete Elements

Pay close attention to the RC beams and spine beams, checking for signs of inadequate compaction, inadequate cover to reinforcement, high rates of carbonation, and surface corrosion of the reinforcement. Ensure that any issues are addressed promptly to maintain the structural integrity of the property.

Maintenance and Repair

Maintaining a BRS Type 4 house requires regular inspections and prompt repairs to address any issues that arise. Here are some key maintenance and repair tips:

External Render

Regularly inspect the external render for signs of cracking and deterioration. Carry out repairs using appropriate materials and techniques to maintain the integrity of the render.

Roof

Inspect the bituminous felt roof cover regularly and carry out repairs as needed. Ensure that any ponding of water is addressed promptly to prevent leaks and structural damage.

Internal Walls and Partitions

Ensure that the property is well-ventilated to prevent internal condensation and mould growth. Carry out repairs to internal partitions as needed to maintain their condition.

Floors

Regularly inspect the concrete ground floor and RC first floor slab for signs of cracking or damage. Carry out repairs as needed to maintain the stability and integrity of the floors.

Ceilings

Inspect the ribbed plaster ceilings regularly and carry out repairs as needed. Ensure that the timber frame panels are in good condition and address any signs of deterioration promptly.

Reinforced Concrete Elements

Regularly inspect the RC beams and spine beams for signs of inadequate compaction, inadequate cover to reinforcement, high rates of carbonation, and surface corrosion of the reinforcement. Carry out repairs as needed to maintain the structural integrity of the property.

Conclusion

The BRS Type 4 house is a unique and historically significant example of post-war British architecture. While these properties come with a range of potential hazards and risks, they can also offer a unique and characterful home for buyers and investors. Understanding the construction and typical issues associated with these properties is essential for making an informed decision.

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.