Overview
The Natcon house is a precast reinforced concrete (PRC) house built between 1960 and 1970, a period of rapid housing development in the UK aimed at affordable, quickly assembled homes. A total of 96 were built, all two-storey and semi-detached.
The houses were manufactured by Natural and Crushed Stone Aggregates Ltd and Peter Cameron (Builders) Ltd, using PRC panels, a popular material at the time for its cost-effectiveness and ease of assembly. The design focused on function and speed of construction.
Typical characteristics & construction
The substructure is a 275 x 450 mm PRC ground beam with a damp-proof course. The external walls are storey-height PRC panels that incorporate the window and door openings, insulated with mineral fibre and with a polyethylene vapour control layer, lined with plasterboard on softwood studs.
Separating walls are 175 mm storey-height PRC panels, which give structural support and sound insulation between the pair. Partitions are timber framed and lined with plasterboard, relatively lightweight and easily altered. Both the ground and first floors are tongue and groove boarding on timber joists, and ceilings are plasterboard. The roof is timber trusses, sarking, battens and interlocking concrete tiles.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | 275 x 450 mm PRC ground beam, DPC | Deterioration of the ground beam, rising damp at the base of the walls |
| External walls | Storey-height roughcast PRC panels, mineral fibre insulation, polyethylene vapour control layer, plasterboard on softwood studs | Cracks, spalling, joints between panels |
| Separating wall | 175 mm storey-height PRC panels | Movement, cracking |
| Partitions | Timber frame lined with plasterboard | Movement, cracking |
| Floors | T&G boarding on timber joists, ground and first floor | Rot, warping or other damage |
| Roof and ceilings | Timber trusses, sarking, battens, interlocking concrete tiles; plasterboard ceilings | Missing tiles, sagging trusses, cracked or stained ceilings |
Potential hazards & inspection priorities
Primary concern: the PRC panels and ground beam
Deterioration of the PRC panels is the most common defect in Natcon houses. Over time the panels develop cracking and spalling and lose structural integrity, which is particularly concerning for the ground beams and external walls on which the stability of the house depends. Significant repairs or reinforcement may follow. The PRC panels should be inspected for cracks, spalling and other deterioration, with particular attention to the joints between panels, which are weak points.
Given the potential for structural issues with PRC panels, a specialist survey by a surveyor experienced in PRC properties is highly recommended to give a detailed assessment of the panels and of any repairs or reinforcement needed.
Secondary concerns: moisture ingress
The PRC panels and the DPC are meant to keep moisture out, but where the DPC is compromised or the panels crack, moisture penetrates the structure. That leads to dampness and mould, affecting both the structure and indoor air quality. The DPC should be intact and functioning, with no signs of rising damp or moisture at the base of the walls. Plasterboard ceilings with cracks, sagging or water stains point to roof leaks or other problems.
Long-term considerations: insulation, roof and timber
The mineral fibre insulation was considered effective when the houses were built, but it does not meet modern energy efficiency standards. Upgrading it is challenging because of the construction method and may require significant expenditure. Its condition should be checked where possible.
The concrete tiles and timber trusses need regular maintenance; missing tiles or sagging trusses lead to leaks. The timber joists in the floors and roof are susceptible to rot, warping and other damage, and should be checked so that problems are dealt with before they become serious.
Is this house right for you?
The Natcon house is an interesting chapter in British residential building, with a distinctive design and historical significance. It also carries the risks that come with PRC panel construction.
- Commission a full building survey
- Have the PRC panels and ground beam assessed by a surveyor experienced in PRC properties
- Check the DPC and look for moisture ingress at the base of the walls
- Allow for insulation upgrades and maintenance of the roof and timber floors
Understanding the construction, the hazards and the common defects puts a buyer in a far better position to decide.
Mortgage & resale considerations
Natcon houses are not designated as defective under the Housing Defects Act 1984. The potential for structural issues, and the use of PRC panels, which have been associated with defects in other property types, mean buyers should exercise caution. A thorough survey by a qualified professional 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 Natcon house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify visible cracking and spalling to the PRC panels and at panel joints
- Assess signs of rising damp, moisture ingress and mould
- Comment on the roof coverings and, where accessible, the roof trusses
- Review the general condition of accessible floors, walls, 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 within the PRC panels and ground beam
- Assess insulation and structure concealed behind the plasterboard linings
- Determine the full extent of any concealed 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.
