Overview
Stonecrete houses were built from 1934 onwards, at a time when the UK was exploring new construction methods to address housing shortages. They were manufactured by the British Cast Concrete Federation and designed by F J Moore Ltd, and they are also known as F J Moore houses after the design firm.
The exact number built is not well documented, but they are relatively common in certain regions. They are found in urban and suburban areas across the UK, often as part of larger housing estates, and are typically two-storey terraced houses. The Aid to Identification: Stonecrete Houses (BRE OP 10, 1983) gives detailed information on their architectural and construction features.
Typical characteristics & construction
The house stands on concrete strip footings with a damp-proof course (DPC), precast concrete (PC) blocks and PRC base units. The frame is made up of 7-inch x 4-inch storey-height PRC posts and PRC corner posts, with a PC ring beam located on dowels protruding from the top of the lower columns. PC first floor sills, L-shaped PC filler blocks between the floor joists and PC eaves-level string units complete the frame.
The external walls are storey-height PC panels that fit into grooves formed in the posts, with reinforced plaster slabs fixed to the posts by T-headed screws. The separating wall is a 4-inch clinker PC cavity wall, and internal partitions are 3-inch or 4-inch plaster blocks. The ground floor is timber and the first floor is timber boarding on timber joists. The roof is timber rafters and purlins covered with tiles.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Concrete strip footings, DPC, PC blocks, PRC base units | Damp and moisture ingress around the DPC and PC blocks |
| Frame | 7-inch x 4-inch storey-height PRC posts, PRC corner posts, PC ring beam on dowels, PC sills, filler blocks and eaves string units | Rust stains, exposed metal, cracking, carbonation |
| External walls | Storey-height PC panels in grooved posts, reinforced plaster slabs fixed by T-headed screws | Cracking, spalling, other damage to panels, signs of corrosion |
| Separating wall and partitions | 4-inch clinker PC cavity wall; 3-inch or 4-inch plaster block partitions | Cracking or movement, damage to plaster blocks |
| Floors | Timber ground floor; timber boarding on timber joists at first floor | Uneven or sagging floors, rot, decay, insect infestation |
| Roof | Medium-pitch hipped; timber rafters, purlins and tiles | Missing or broken tiles, sagging, water ingress, rot to rafters and purlins |
Potential hazards & inspection priorities
Primary concern: corrosion of steel reinforcement
Corrosion of the steel reinforcement within the PRC panels is one of the most significant issues with Stonecrete houses. It leads to structural instability, and it is the reason the type needs careful inspection and maintenance. Rust stains and exposed metal are the evidence to look for. Where corrosion is found it needs addressing promptly, which involves removing and replacing affected panels, applying corrosion inhibitors or using cathodic protection systems.
Primary concern: carbonation, cracking and spalling
Carbonation, where carbon dioxide penetrates the concrete and reduces its alkalinity, affects the durability of the reinforced concrete components. Carbonation testing establishes how far it has progressed and what that means for the structure. Cracking and spalling of the concrete panels are common defects that compromise structural integrity and can require extensive repairs. They should be repaired as soon as they are identified, by patching with suitable repair materials or replacing damaged panels.
Published guidance on assessing the durability of reinforced concrete includes Corrosion of Steel in Concrete (BRE Digest 444, Parts 1 to 3), Repair and Maintenance of Reinforced Concrete (BR 254) and Carbonation Depths in Structural-Quality Concrete (BR 19).
Secondary concern: damp and moisture
Damp and moisture ingress around the DPC and PC blocks leads to further structural problems and remedial work. The DPC and PC blocks need to be in good condition and working effectively, and the roof, gutters and downpipes kept in order so that water does not enter the property.
Long-term considerations: timber, partitions and regular inspection
The timber rafters and purlins are susceptible to rot and decay, and the floors should be checked for movement, sagging, rot, decay and insect infestation. The plaster block partitions are prone to damage, and they and the separating wall should be checked for cracking or movement. Regular inspection is the basis of looking after these houses: at least annually, and more frequently where significant defects have been identified.
Is this house right for you?
The Stonecrete house is a distinctive and historically significant type, but its classification as defective and the condition of its reinforced concrete are what a purchase turns on. Gathering information before inspection, including construction details, previous maintenance records and any known issues, focuses attention on the areas that matter.
- Commission a full building survey
- Obtain any previous maintenance records and known history of repairs
- Establish whether the reinforcement shows signs of corrosion
- Consider carbonation testing of the concrete components
- Plan for regular, at least annual, inspection
Thorough inspection and prompt attention to issues are what secure the long-term durability and safety of a Stonecrete house.
Mortgage & resale considerations
Stonecrete houses are designated as defective under the Housing Defects Act 1984, because of the potential for structural issues arising from the use of PRC in their construction. Buyers should be aware of this designation and the risks that go with it.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of a Stonecrete house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify visible cracking, spalling, rust staining and exposed metal to the PRC posts and panels
- Assess signs of damp and moisture ingress around the DPC and PC blocks
- Comment on the roof, rafters and purlins, and rainwater goods
- Review the condition of accessible floors, the separating wall and plaster block partitions
- 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 components
- Measure the depth of carbonation without carbonation testing
- Assess structural elements hidden behind linings and finishes
- 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.
