Overview
The Bellrock house is a system-built house from the 1940s, a period of significant demand for housing driven by the shortage after the Second World War. It was one of many system-built types designed to be put up rapidly and efficiently, while being durable and comfortable for the occupants.
The houses were manufactured by Sound City, and only 18 were built. They take two forms: chalet bungalows and two-storey semi-detached houses.
Typical characteristics & construction
The house stands on concrete strip foundations. The external walls are storey-height, 4-inch loadbearing Bellrock hollow-cored plaster panels, clad directly with brick. Over large openings, reinforced concrete (RC) lintels are formed in the inner leaf by breaking out the internal webs of the Bellrock panels; in the outer leaf, lintels are formed from three courses of reinforced brick. Some houses are harled throughout rather than brick-faced.
The ground floor is a concrete slab. The first floor is tongue and groove boarding on timber joists supported by rolled steel angles (RSAs). Ceilings are recessed-edge plasterboard. The roof is timber rafters on a softwood timber wall plate, a traditional form of construction that allows the steep pitch.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Concrete strip foundations | Rising damp at the base of walls |
| External walls | Storey-height 4-inch loadbearing Bellrock hollow-cored plaster panels, clad directly with brick or harled | Cracking, bulging, movement; damp, staining, efflorescence |
| Lintels | RC lintels in the inner leaf; three courses of reinforced brick in the outer leaf | Corrosion or deterioration, cracking around windows and doors |
| Ground floor | Concrete slab | Cracking or movement |
| First floor | T&G boarding on timber joists on RSAs | Rot or insect infestation; corrosion of the RSAs |
| Ceilings | Recessed-edge plasterboard | Sagging, water damage |
| Roof | Timber rafters on softwood wall plate, plain clay tiles | Missing or broken tiles, sagging, rot or insect infestation |
Potential hazards & inspection priorities
Primary concern: damp and moisture ingress
Given the age of these houses, damp and moisture ingress are a common issue, made worse by the hollow-cored plaster panels in the external walls, which let moisture through where they are not properly sealed and maintained. Damp leads to mould growth, timber decay and damage to internal finishes. Walls should be checked for staining, efflorescence and mould, and a moisture meter used on walls and floors, with particular attention to the base of the walls, where rising damp is a risk.
Keeping moisture out means keeping the house well sealed and maintained: repairing damaged or missing roof tiles, keeping gutters and downpipes clear and working, and applying waterproof coatings to the external walls. Installing a damp-proof course, and keeping it in good condition, helps prevent rising damp.
Primary concern: the reinforced concrete elements
The reinforced concrete elements are the main structural concern. Over time the steel reinforcement corrodes and weakens the structure, particularly in houses that have not been well maintained or have been exposed to harsh conditions. The external walls should be examined for cracking, bulging or movement, with particular attention to the areas around windows and doors where the RC lintels sit, and for signs of corrosion or deterioration of the concrete. Repairs involve removing and replacing damaged concrete and applying protective coatings to prevent further corrosion.
Secondary concern: timber and steelwork
The roof should be checked for missing or broken tiles, sagging or unevenness, and the rafters and wall plate for rot or insect infestation. Inside, the first floor boarding and joists need the same checks, with particular attention to the RSAs, which are prone to corrosion. The ground floor slab should be checked for cracking or movement, the internal walls for cracking, movement or damp, and the ceilings for sagging or water damage. Timber elements need regular maintenance, including preservative treatment and repair or replacement of damaged or decayed sections.
Long-term consideration: thermal efficiency
The brick cladding provides thermal mass, but the overall thermal efficiency of the house does not meet modern standards, which means higher heating costs and less comfort. Insulation levels in the walls, floors and roof should be checked, along with draughts and air leakage; a thermal imaging camera helps identify heat loss. Improvements include adding insulation to the walls, floors and roof, upgrading windows and doors to double or triple glazing, and sealing gaps and draughts.
Is this house right for you?
The Bellrock house is a distinctive type, with only 18 built. It does not meet modern standards and is prone to structural concerns, damp and poor thermal efficiency, but with careful inspection, maintenance and upgrading it can be made a comfortable home.
- Commission a full building survey
- Check the walls for damp, and the areas around openings for cracking and lintel corrosion
- Check the roof timbers, floor joists and RSAs for decay and corrosion
- Obtain previous survey reports, maintenance records, planning permissions and, if available, the original construction plans
- Plan for damp control, insulation and timber maintenance
Understanding the characteristics, hazards and risks of these houses is the basis for an informed decision.
Mortgage & resale considerations
Bellrock houses are not designated as defective under the Housing Defects Act 1984. They were built to the standards of their time, however, and may not meet modern building regulations, particularly where their condition poses a risk to the health and safety of occupants.
Buyers should be aware of this and make sure any necessary repairs and upgrades are carried out to bring the property up to current standards, including dealing with structural issues, improving thermal efficiency and keeping the house free from damp.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of a Bellrock house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify cracking, bulging or movement to external walls, particularly around openings
- Assess signs of dampness, staining, efflorescence and mould, including with a moisture meter
- Comment on roof tiles and accessible roof timbers
- Review the condition of accessible floors, ceilings and internal walls
- 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 the Bellrock plaster panels concealed behind the brick cladding
- Confirm the condition of reinforcement within the RC lintels and reinforced brick courses
- Assess RSAs and joists hidden within the first floor
- 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.
