The MOW Demonstration No-Fines House

The MOW Demonstration No-Fines house is a rare non-traditional property type developed in the 1940s by the Ministry of Works (MOW) as part of the post-war housing programme. Only two of these houses were built, making surviving examples highly uncommon.

The term “No-Fines” refers to the concrete used in construction. Unlike traditional concrete, which incorporates fine aggregates such as sand, No-Fines concrete uses only coarse aggregates and cement. This produces a lighter, more porous material intended to reduce material use and improve thermal performance when compared with dense concrete construction of the same era.

The MOW Demonstration No-Fines house, a two-storey semi-detached post-war property constructed using reinforced no-fines concrete.

MOW Demonstration No-Fines houses are two-storey semi-detached dwellings with steep pitch gable roofs covered in tiles. External walls are fully rendered, providing a uniform external appearance. A flat canopy above the entrance door is a distinguishing feature.

Ground floors are formed in concrete, while first floors comprise timber boarding laid over timber joists. The detailed construction of ceilings is not well documented but is consistent with post-war housing practice of the period.

The principal structural elements include concrete strip footings with dense concrete underbuilding, a concrete slab incorporating a damp-proof course (DPC), 12-inch clinker aggregate No-Fines concrete external walls reinforced with 3/8-inch continuous bar reinforcement encased in cement mortar, an 8-inch ballast aggregate No-Fines concrete separating wall, and 4-inch ballast aggregate No-Fines concrete internal partitions. Roofs are formed using timber rafters and purlins finished with tiles.

The principal risk associated with this construction relates to the porous nature of No-Fines concrete. Moisture penetration can, over time, reach embedded steel reinforcement. Corrosion of reinforcement bars may result in expansion, cracking, and localised spalling of the concrete, affecting structural performance.

Thermal insulation levels are modest by modern standards. While No-Fines concrete offered improved thermal performance compared with dense concrete of its era, additional insulation is often required to meet current energy efficiency expectations.

Damp and moisture control remain critical. Failure or bridging of the damp-proof course can permit moisture to migrate through the slab and lower wall sections, leading to internal dampness and associated deterioration.

MOW Demonstration No-Fines houses are not designated as defective under the Defective Premises Act. Nevertheless, their non-traditional reinforced concrete construction warrants careful technical assessment.

A MOW Demonstration No-Fines house will appeal to purchasers who recognise its historical significance and understand the implications of reinforced concrete construction.

• Awareness of potential moisture-related deterioration
• Willingness to maintain render and external envelope
• Acceptance that insulation standards differ from modern construction

Condition and maintenance history are central considerations in assessing suitability.

Mortgage lending decisions are influenced by construction type, structural condition, and clarity of professional reporting. Reinforced concrete properties can be acceptable to lenders, provided condition is satisfactory and no significant structural deterioration is identified.

Clear documentation of repairs, evidence of sound maintenance, and absence of progressive cracking are commonly influential factors in lending and future resale.

A building survey provides an informed assessment of the visible condition and construction of a MOW Demonstration No-Fines house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.

• Identify visible cracking and spalling to no-fines concrete walls and render
• Assess signs of dampness, moisture ingress, and condensation risk
• Comment on roof coverings, drainage details, and external envelope condition
• Review the general condition of accessible floors, ceilings, and structural elements
• Highlight defects that may require 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 no-fines concrete walls
• Assess hidden structural elements behind finishes or linings
• Determine the full extent of internal concrete deterioration
• 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.