Overview
The Crosby house is a precast concrete, system-built bungalow from the 1940s, built to meet the demand for affordable housing after the Second World War. It was manufactured by J Crosby & Sons Ltd. The identity of the designer is less well documented, but the construction reflects the period's emphasis on rapid, cost-effective building.
Exact numbers are not readily available, but the houses were built in quantity to meet the housing needs of the time. They are found in suburban areas, particularly in regions that expanded quickly after the war and needed housing for returning soldiers and their families. They are detached and semi-detached bungalows.
Typical characteristics & construction
The house sits on a concrete raft foundation, thickened around the perimeter to form downstand beams. The external walls are 8 1/4-inch hollow lightweight PC wall panels, rendered, with 9-inch PRC ring beams. Windows have PRC sills and mullions.
Separating walls are concrete block cavity walls. Internal partitions are lightweight concrete blocks, although some houses have timber stud partitions lined with plasterboard instead. The ground floor is concrete covered with asphalt, and the ceilings are plasterboard. The roof is light steel trusses and timber rafters covered with concrete tiles.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Concrete raft thickened at the perimeter to form downstand beams | Movement or cracking, condition of the downstand beams |
| External walls | Rendered 8 1/4-inch hollow lightweight PC panels, 9-inch PRC ring beams, exposed cover strips to flank walls | Cracks, spalling, deterioration, condition of cover strips |
| Windows | PRC sills and mullions | Corrosion or structural weakness, draughts and heat loss |
| Separating wall and partitions | Concrete block cavity wall; lightweight concrete block or timber stud partitions | Movement or cracking |
| Ground floor | Concrete covered with asphalt | Settlement or cracking, damage to the asphalt |
| Roof and ceilings | Light steel trusses, timber rafters, concrete tiles; plasterboard ceilings | Missing or cracked tiles, condition of rafters and trusses, water damage or sagging |
Potential hazards & inspection priorities
Primary concern: reinforcement corrosion and carbonation
The main concern with Crosby houses is structural degradation over time. The steel reinforcement within the concrete corrodes and weakens the structure, particularly where moisture levels are high. Carbonation reduces the alkalinity of the concrete and leaves the reinforcement more open to corrosion, a common issue in older concrete structures. Non-destructive testing, such as a cover meter or half-cell potential measurement, assesses the extent of corrosion, and the depth of carbonation can be measured with phenolphthalein solution. Corrosion needs regular monitoring and maintenance.
Secondary concerns: the walls and structure
The rendered PC panels develop cracks, and the concrete spalls, through weathering and structural movement. The panels should be checked for cracks, spalling and other deterioration, with particular attention to the exposed cover strips on the flank walls. The PRC sills and mullions should be checked for corrosion or weakness, partitions for movement or cracking, and the raft and its downstand beams for movement or cracking. Repairs to cracks and corrosion keep minor problems from becoming major structural concerns.
Long-term considerations: thermal efficiency and asbestos
Like many 1940s houses, the Crosby house does not meet modern thermal efficiency standards. The hollow lightweight PC panels give limited insulation, and the construction method leads to thermal bridging, causing heat loss and condensation. Insulation to the walls, roof and floors should be checked and upgraded, and windows and doors assessed for draughts and heat loss.
Asbestos was commonly used in building materials in the 1940s. This is not specific to Crosby houses, but its presence should be checked, particularly in insulation, roofing materials and floor tiles. An asbestos survey identifies any asbestos-containing materials, which must then be managed or removed safely in line with current regulations.
Is this house right for you?
The Crosby house is a product of post-war ingenuity, and like any house of its era it comes with its own set of challenges. Its condition depends on its concrete.
- Commission a full building survey
- Establish the extent of reinforcement corrosion and carbonation
- Gather previous maintenance records and any known issues
- Arrange an asbestos survey and allow for insulation upgrades
Regular inspection, and early attention to what it finds, is what keeps a Crosby house safe over the long term.
Mortgage & resale considerations
The Crosby house is not designated as defective under the Housing Defects Act 1984. The potential for structural issues from corrosion and carbonation still makes thorough inspection crucial, and any necessary repairs or reinforcement should be carried out to maintain the safety and value of the property.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of a Crosby house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify visible cracking and spalling to the rendered PC panels and cover strips
- Comment on PRC sills and mullions and visible signs of corrosion
- Assess signs of dampness, condensation and heat loss
- Review the general condition of the roof, floors, partitions and ceilings
- 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 reinforcement concealed within the PRC elements
- Measure carbonation depth without testing
- Confirm whether materials contain asbestos without specialist sampling
- 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.