Overview
The Smith house is a precast reinforced concrete house built between 1945 and 1955. It was manufactured by Smith's Building Systems, and approximately 4,500 were built. The type is also known as British Steel Construction, or BSC.
The houses are two-storey, semi-detached or terraced, and are found mainly in suburban areas, particularly in regions that suffered serious housing shortages after the Second World War. They were designed to provide affordable and durable housing for a growing population.
Typical characteristics & construction
The house sits on a concrete slab thickened to form strip foundations under the external walls. The external walls are foamed slag PRC panels, 2 feet 6 inches by 7 feet and 8 inches thick at ground floor, 6 inches thick at first floor, faced with 1.25-inch brick slips. The panels are joined with concrete grout or mortar in grooved horizontal and vertical joints, secured with mild steel staples, and dense reinforced concrete lintels span the openings.
The separating wall is 8-inch foamed slag PRC panels, and the partitions are 4-inch foamed slag concrete. The ground floor is timber block on a 2-inch foamed slag screed over concrete. The first floor is timber boarding on timber joists, carried on the ground floor PRC panels with brick noggins. The ceiling construction is not documented.
The roof is timber rafters and purlins covered with concrete tiles. Some houses have a roof of light steel trusses and grooved lightweight precast concrete decking under the tiles, and some have rendered rather than brick-slip-faced external walls.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Concrete slab thickened to form strip foundations under external walls | Foundation movement: uneven floors, cracked walls, sticking doors and windows |
| External walls | Foamed slag PRC panels (8-inch ground floor, 6-inch first floor), brick slip facing or render, grouted joints, MS staples, dense RC lintels | Cracking of and between panels, render cracking and water ingress |
| Window surrounds and sills | PRC units | Spalling, rusting reinforcement, water ingress |
| Separating wall and partitions | 8-inch foamed slag PRC panels; 4-inch foamed slag concrete partitions | Cracking at junctions with external walls |
| Floors | Timber block on foamed slag screed on concrete; timber boarding on joists at first floor | Movement, uneven surfaces, creaking boards |
| Ceilings | Not documented | Sagging, water damage |
| Roof | Timber rafters and purlins, concrete tiles; variant with light steel trusses and lightweight PC decking | Rot, insect attack, damaged tiles, watertightness |
Potential hazards & inspection priorities
Primary concern: foundation movement
Foundation movement is one of the most common issues with Smith houses. It leads to structural instability and calls for careful monitoring and, potentially, remedial work. The signs are uneven floors, cracked walls, and doors or windows that do not close properly. Where movement is found, a structural engineer should assess its extent and recommend remedial work, which may include underpinning or other stabilisation.
Primary concern: cracking of the PRC panels and junctions
Cracking is the other common defect, occurring in and between the PRC panels and at the junctions of the external walls, partitions and separating wall. These cracks compromise structural integrity and need professional assessment and repair. In practice, prompt repair limits further deterioration; this may mean filling the cracks with suitable materials and, in some cases, reinforcing the affected areas. Inside, the partitions should be checked for cracks where they meet the external and separating walls.
Secondary concern: PRC window surrounds and sills
The PRC window surrounds and sill units deteriorate over time, which lets water in and leads to further structural problems. Spalling concrete and rusting reinforcement are the signs to look for. Deteriorated units should be replaced with new, more durable units to stop water ingress.
Long-term consideration: variants and the roof
Rendered external walls are more susceptible to cracking and water ingress than brick slip facing, so the render needs inspecting and any issues dealing with promptly. Roofs built with light steel trusses and lightweight precast concrete decking have different maintenance requirements and potential issues from the standard timber roof. On the standard roof, the rafters and purlins should be checked for rot, insect infestation or other damage, and the tiles for damage, wear and watertightness.
Is this house right for you?
The Smith house is a notable part of the UK's post-war housing stock, but it carries the defects that come with its PRC construction. Thorough inspection and prompt attention to issues are what maintain its structural integrity and value.
- Commission a full building survey
- Look first for evidence of foundation movement
- Check the PRC panels, their joints and the wall junctions for cracking
- Establish the condition of the PRC window surrounds and sills
- Take the designated defective status into account
Being aware of the typical defects and hazards before buying makes for a better-informed decision.
Mortgage & resale considerations
Smith houses are designated defective under the Housing Defects Act 1984 because of the inherent issues with their PRC construction. Buyers need to be aware of the potential risks and of the remedial work that may be necessary when considering one of these houses.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of a Smith house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify visible signs of foundation movement
- Identify visible cracking of and between PRC panels and at wall junctions
- Assess the condition of PRC window surrounds and sills, including spalling and rusting reinforcement
- Comment on the render or brick slip facing, roof structure and coverings
- 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 and staples concealed within the PRC panels and joints
- Determine the cause and extent of foundation movement without structural engineering investigation
- Assess structural elements hidden behind brick slips, render or linings
- 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.
