Overview
The Stewart & Partners Type I house is a precast reinforced concrete (PRC) house from the 1920s, designed and manufactured by Stewart & Partners Ltd. It was built at a time of significant demand for affordable housing after the First World War, when a growing population needed homes.
The houses are found mainly in suburban areas across the UK, often in what were then newly developed residential areas, and particularly in regions that saw rapid urban expansion during the 1920s. Exact numbers built are not readily available.
Typical characteristics & construction
The house stands on concrete strip footings with concrete underbuilding and a damp-proof course. The external walls are built from hollow PRC columns, assembled in sections, with dense aggregate ribbed PRC panels on the outside, a cavity, and clinker ribbed PRC panels on the inside. Reinforced concrete ring beams run at first floor and eaves level. The walls are rendered throughout.
Little is documented about the rest of the house. The construction of the internal walls and partitions, the ground and first floors and the ceilings is not well known. The roof is hipped, at a medium pitch, and covered with tiles.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Concrete strip footings, concrete underbuilding, DPC | Settlement or movement, effectiveness of the DPC |
| External walls | Hollow PRC columns, dense aggregate ribbed PRC panels, cavity, clinker ribbed PRC panels; rendered | Cracks, spalling and other deterioration, especially to columns and panels |
| Ring beams | Reinforced concrete at first floor and eaves level | Cracking, spalling |
| Roof | Medium-pitch hipped roof, tiled | Missing or broken tiles, condition of the structure, drainage |
| Internal walls and partitions | Not well documented | Signs of structural issues or damage |
| Floors and ceilings | Not well documented | Sagging, cracking, water damage |
Potential hazards & inspection priorities
Primary concern: carbonation and corrosion of the reinforcement
The main concern with this house is the durability of its reinforced concrete. Over time the steel reinforcement corrodes and the structure weakens, particularly where the property has not been adequately maintained or has been exposed to harsh conditions.
Carbonation is the process behind it. Carbon dioxide from the air penetrates the concrete and reacts with calcium hydroxide to form calcium carbonate, lowering the pH of the concrete and leaving the steel more susceptible to corrosion. Corroding steel leads to cracking, spalling and, ultimately, structural failure. The external walls should be examined for cracks, spalling and other deterioration, with particular attention to the PRC columns and panels, which are critical to the structure. Regular inspection and maintenance are what catch these problems early.
The relevant references for an inspection are the Moir Report and the BRE guidance on reinforced concrete durability: 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: moisture ingress
Moisture ingress leads to dampness, mould growth and structural damage. The concrete strip footings and underbuilding should be checked for settlement or movement, and the damp-proof course for its effectiveness in keeping moisture out. Drainage around the property needs to stop water accumulating at the foundations.
Secondary concern: the roof
The roof should be checked for missing or broken tiles, and the hipped roof structure for its condition and for adequate drainage of water. Damaged tiles need replacing promptly to prevent leaks and water damage.
Long-term consideration: undocumented elements
Because the internal walls, partitions, floors and ceilings are not well documented, each needs inspecting on its own merits for structural issues, damage, sagging, cracking or water damage.
Is this house right for you?
The Stewart & Partners Type I house is a historically significant 1920s house type. It brings benefits and challenges, and the challenges centre on the reinforced concrete.
- Commission a full building survey
- Establish the condition of the PRC columns, panels and ring beams first
- Check the damp-proof course and drainage around the foundations
- Plan for regular roof inspection and maintenance
Understanding the typical characteristics, hazards and maintenance needs of these houses is the basis for an informed decision.
Mortgage & resale considerations
The Stewart & Partners Type I house is not designated defective under the Housing Defects Act 1984. Given the potential issues with reinforced concrete durability, a thorough inspection and assessment before purchase is crucial.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of a Stewart & Partners Type I 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 PRC walls and ring beams
- Assess signs of dampness, moisture ingress and settlement
- Comment on the roof covering and the visible roof structure
- Review the general condition of accessible floors, ceilings, walls and 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 columns, panels and ring beams
- Determine carbonation depth without testing
- Assess structural elements hidden behind render, finishes 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.
