Overview
The Spacemaker house is a system-built precast reinforced concrete house built in the UK between 1959 and 1970. It was both designed and manufactured by the Shepherd Building Group Ltd, and around 2,750 were built. It is also known as Conspan, Shepherd and Shepherd Spacemaker.
The houses were built at a time of housing shortage, when there was a significant push towards system-built homes that could be assembled quickly and efficiently. Shepherd used prefabricated reinforced concrete (PRC) panels to cut construction time and cost. Spacemaker houses are found mainly in suburban areas across the UK, as bungalows and two- and three-storey terraced houses. NBA Certificates for the system were issued in April 1966 and March 1969.
Typical characteristics & construction
The house stands on precast concrete ground beams with a two-coat bituminous compound damp-proof course. The front and rear walls are eaves-height, room-width PRC panels located by metal dowels and tied to the gable wall panels with metal angle brackets. Between them sit storey-height timber frame panels clad with vertical timber boarding and lined with plasterboard, with insulation between the studs.
The gable walls are eaves-height, room-width PRC panels with PRC apex panels, bedded on mortar, located by metal dowels and lined with polystyrene insulation and plasterboard laminate nailed to timber fillets. Each panel has a drainage hole to prevent moisture building up. The separating walls are eaves-height PRC panels supported on dry-pack, bolted together with metal connecting plates and lined with polystyrene insulation and plasterboard laminate.
Internal partitions are loadbearing storey-height timber frame panels, lined with plasterboard to first floor level and honeycomb plasterboard to the upper floors. The ground floor is concrete. Upper floors are timber joists on timber bearers bolted to the front or rear PRC panels. Ceilings are plasterboard, which gives a smooth finish and a degree of fire resistance. The roof is timber trussed rafters covered with concrete tiles or bituminous felt, depending on the design.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Precast concrete ground beams; two-coat bituminous compound DPC | DPC intact and effective |
| Front and rear walls | Eaves-height room-width PRC panels; storey-height timber frame infill panels clad in vertical boarding, insulated, plasterboard lined | Cracking and spalling at exposed panel ends; moisture and rot in timber panels and cladding |
| Gable walls | Eaves-height room-width PRC panels and apex panels, polystyrene and plasterboard laminate lining, drainage hole per panel | Cracking, spalling, damage |
| Separating walls | Eaves-height PRC panels on dry-pack, bolted with metal plates, polystyrene and plasterboard laminate lining | Cracking, movement |
| Roof perimeter beams | PRC | Cracking, spalling |
| Floors | Concrete ground floor; timber joists on bearers bolted to PRC panels above | Cracking or movement at ground floor; level, without excessive deflection, above |
| Partitions and ceilings | Loadbearing timber frame panels, plasterboard or honeycomb plasterboard; plasterboard ceilings | Signs of moisture ingress |
| Roof | Timber trussed rafters with concrete tiles or bituminous felt | Wear, damage, leaks |
Potential hazards & inspection priorities
Primary concern: the PRC panels and perimeter beams
The most common defects in Spacemaker houses involve the PRC panels. Cracking and spalling of the exposed ends of the panels and of the roof perimeter beams is the issue to look for first. The concrete may contain blast furnace aggregate, and the panels are associated with high rates of carbonation and low reinforcement cover. Over time these compromise the structural integrity of the house. Any cracks or damage to the panels need inspecting and repairing.
Secondary concerns: timber panels, cladding and moisture
The timber frame infill panels and their vertical boarding are susceptible to moisture ingress and rot where they are not properly maintained. Inside, the plasterboard linings and timber frame panels should be checked for signs of moisture, which point to problems with the external cladding or the roof. The roof covering, whether concrete tiles or felt, needs to be in good condition and free from leaks, and the damp-proof course intact and effective.
Long-term consideration: floors and ongoing maintenance
The concrete ground floor should be checked for cracking or movement, and the upper floors for level and for excessive deflection. Regular maintenance of the PRC panels, the roof, the timber cladding and frame panels, and the damp-proof course is what keeps a Spacemaker house durable.
Is this house right for you?
The Spacemaker house is a historically significant system-built type. It was quick and affordable to build, but the PRC panels bring known risks and the timber elements need regular maintenance.
- Commission a full building survey
- Review any available NBA Certificates (April 1966, March 1969) and information on the construction
- Establish the condition of the PRC panel ends and roof perimeter beams
- Check the timber cladding and infill panels for moisture and rot
- Plan for regular maintenance of the roof, cladding and damp-proof course
Understanding the construction and the common defects puts a buyer in a far better position to judge the long-term durability and safety of the house.
Mortgage & resale considerations
Spacemaker houses are not designated defective under the Housing Defects Act 1984. Because of the structural issues associated with the PRC panels, a thorough survey to identify existing or developing defects is essential before purchase.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of a Spacemaker house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify visible cracking and spalling to exposed PRC panel ends and roof perimeter beams
- Assess the timber cladding and infill panels for rot and moisture ingress
- Comment on roof coverings and the external envelope
- Review the condition of accessible 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.
- Measure carbonation depth or reinforcement cover in the PRC panels
- Confirm whether the concrete contains blast furnace aggregate
- Assess concealed fixings, brackets and timber behind linings and cladding
- 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.
