Overview
The Corvus house is a rare post-war non-traditional property manufactured by William Cowlin & Son Ltd and designed by N. Rooke. Constructed in 1946 in response to the acute housing shortage following the Second World War, only four examples were built, making this an exceptionally uncommon house type.
It is a two-storey semi-detached dwelling with a medium to steep pitch gable roof finished in interlocking or plain concrete tiles. External walls are fully rendered. A distinctive monopitch canopy supported by concrete columns protects the front entrance, and a pitched roof single-storey extension is commonly formed off the gable wall.
Corvus Houses were constructed using reinforced concrete cavity wall construction with foamed slag concrete inner leaves and pre-stressed reinforced concrete floor and roof components. Only four units were built in 1946.
Typical characteristics & construction
The substructure comprises concrete strip footings with concrete under-building. The main walls are 10-inch reinforced concrete cavity construction incorporating a damp-proof course.
The outer leaf is formed in 4-inch dense concrete and the inner leaf in 4-inch foamed slag concrete, separated by a 2-inch cavity. Reinforcement is present at eaves level, with additional mild steel bars below first floor level. Weep holes and cavity trays are provided above openings.
The separating wall between the semi-detached units is also of foamed slag reinforced concrete cavity construction. Ground floor partitions are 4-inch or 6-inch foamed slag concrete, with 2.5-inch foamed slag concrete partitions at first floor level.
The ground floor is finished in mastic asphalt laid on concrete. The first floor comprises mastic asphalt on sand/cement screed supported by 12-inch by 5-inch hollow pre-stressed reinforced concrete beams built into the inner leaf and reinforced with 0.5-inch steel bars.
The roof structure uses pre-stressed reinforced concrete rafters, purlins and ceiling joists, finished with concrete tiles. The chimney is also formed in reinforced concrete.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Concrete strip footings and concrete under-building | Settlement, cracking and movement |
| External walls | 10-inch reinforced concrete cavity wall with dense concrete outer leaf and foamed slag inner leaf | Cracking, spalling, carbonation and moisture ingress |
| Floors | Mastic asphalt on concrete (ground floor); PRC beams with screed and asphalt (first floor) | Beam condition, deflection, cracking and dampness |
| Roof | PRC rafters, purlins and joists with concrete tiles | Concrete durability, tile condition and structural integrity |
| Chimney | Reinforced concrete | Cracking, stability and weathering |
Potential hazards & inspection priorities
The principal technical concern with this house type relates to reinforced concrete durability. Corrosion of embedded steel can occur where concrete cover is limited or where prolonged moisture exposure has taken place, leading to cracking and spalling.
Carbonation of concrete reduces alkalinity and increases the risk of reinforcement corrosion. Moisture ingress remains a secondary but important factor, particularly if weep holes, cavity trays or render finishes are defective.
The 2-inch cavity provides limited thermal performance by modern standards, which can contribute to condensation risk and thermal bridging. Given the 1946 construction date, the potential presence of asbestos-containing materials in ancillary components should also be considered.
The Corvus house is not specifically designated as defective under the Defective Premises Act, but its reinforced concrete construction warrants careful technical assessment.
Is this house right for you?
Purchasers considering a Corvus house should understand that it is a rare non-traditional reinforced concrete system. Structural condition, durability of pre-stressed elements and moisture control are more significant than internal finishes.
- Obtain a detailed building survey focusing on reinforced concrete condition
- Assess evidence of past repairs to spalled or cracked concrete
- Review maintenance of render, drainage and roof coverings
- Clarify whether any asbestos-containing materials have been identified
Mortgage & resale considerations
Lending decisions for non-traditional reinforced concrete properties depend on construction type, condition and clarity of professional reporting. Durability concerns relating to reinforced concrete and pre-stressed components are commonly examined.
Clear evidence of sound structural condition, absence of active corrosion and documented maintenance will be influential in supporting future resale.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of a Corvus house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify visible cracking, spalling or rust staining to reinforced concrete walls and structural elements
- 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, beams and structural components
- 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 internal condition of concealed reinforcement within concrete elements
- Assess hidden structural connections or embedded steel within floors and roof members
- Determine the full extent of carbonation within reinforced concrete
- 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.
Considering a Corvus House?
A detailed building survey can help clarify construction-specific risks before committing to a purchase.
Get your instant survey quoteDisclaimer: This article is provided for general educational purposes only and is based on industry research, professional knowledge, and experience. It does not relate to any specific property and should not be relied upon when making a purchasing decision. Prospective purchasers should always commission an independent RICS-qualified surveyor to conduct a full inspection and provide a report on the actual condition of any property of interest.
