The Unity Type I House

The Unity Type I house is a form of post-war, non-traditional housing developed during the 1950s to address acute housing shortages following the Second World War. Manufactured by Unity Structures Ltd and Unity House Construction, these system-built homes were designed to be erected quickly and economically.

Around 19,000 Unity Type I and Type II properties were constructed across the UK, commonly forming part of suburban estates built to accommodate growing urban populations.

A Unity Type I house illustrating typical roof form and precast concrete external wall construction.

Unity Type I houses were constructed as bungalows or two-storey semi-detached and terraced houses. Roofs are medium-pitched, either hipped or gabled, and typically finished with concrete tiles. Tile hanging is often present at gable apexes, with splayed precast concrete corner blocks forming a distinctive feature.

The primary structure comprises storey-height precast reinforced concrete columns tied together with horizontal and diagonal steel bracing. External walls are formed using precast concrete panels creating a cavity construction, with some examples finished in partial or full brick cladding.

The most significant risks associated with Unity Type I houses relate to deterioration of precast reinforced concrete components. Longitudinal cracking to columns and spalling of lintels are commonly encountered and can indicate reinforcement corrosion.

Corrosion is also frequently observed at the interface between PRC columns and RSJ first-floor beams, as well as to copper fixings securing external cladding. Elevated chloride levels within the concrete can accelerate this process.

Asbestos cement roofing sheets are a further consideration. While often stable if undisturbed, they present a health risk if damaged or altered.

Unity Type I houses require purchasers to understand non-traditional construction and the implications of owning a property designated as defective under the Defective Premises Act.

• Commission a full building survey by an experienced surveyor
• Be prepared for ongoing monitoring and maintenance of structural elements
• Consider the implications of asbestos-containing materials

Mortgage availability for Unity Type I houses can be restricted due to their construction type and statutory designation. Lender requirements vary and are closely linked to condition, evidence of repairs, and the quality of professional reporting.

Clear survey findings and documented remedial works are commonly influential in mortgage and resale decisions.

A building survey provides an informed assessment of the visible condition and construction of a Unity Type I house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.

• Identify visible cracking to PRC columns, panels, and lintels
• Assess signs of dampness, moisture ingress, and condensation risk
• Comment on roof coverings, drainage details, and the external envelope
• Review the general condition of accessible floors, ceilings, and structural elements
• Highlight defects requiring repair, monitoring, or further investigation

However, there are limitations to what a survey can determine without intrusive investigation.

• Confirm the condition of concealed reinforcement within precast concrete
• Assess hidden structural elements behind finishes or linings
• Determine the full extent of internal concrete deterioration or chloride contamination
• Inspect areas that are inaccessible or covered at the time of inspection

Where higher-risk indicators are identified, further specialist or intrusive investigation may be recommended.

For a thorough building survey in Greater London, an instant quotation can be obtained through the online survey calculator.