Overview
The Arcal house is a system-built form of non-traditional housing developed in the 1960s. Designed and manufactured by Gee Walker & Slater, this construction type formed part of a wider post-war move toward prefabricated housing solutions intended to speed up delivery and control costs.
Only around 100 Arcal houses were constructed, making them relatively uncommon. They are usually encountered as bungalows or two-storey semi-detached and terraced houses.
Arcal houses were produced during the 1960s housing boom and are characterised by medium-pitch gable roofs with interlocking concrete tiles, rendered external walls, flat-roofed front lobbies, and metal window frames.
Typical characteristics & construction
Arcal houses are constructed on concrete footings with a brick underbuilding supporting a concrete ground-bearing slab incorporating a damp-proof course. The superstructure uses a platform timber frame system formed from storey-height prefabricated panels.
Externally, the timber panels are sheathed in plywood, overlaid with bituminous paper, and finished with render applied over expanded metal mesh. Internally, walls are lined with foil-backed plasterboard. Separating walls between dwellings are formed in 11-inch block cavity construction.
Ground floors are concrete slabs, with first floors formed from tongue-and-groove boarding on timber joists. Roofs are timber trussed structures covered with bituminous felt and interlocking concrete tiles.
| Element | Typical construction | Inspection focus |
|---|---|---|
| Substructure | Concrete footings, brick underbuilding, concrete slab with DPC | Settlement, cracking, damp-proof course continuity |
| External walls | Timber frame panels with plywood sheathing and rendered finish | Timber decay, render cracking, moisture ingress |
| Separating walls | 11-inch block cavity wall | Cracking, sound insulation performance |
| Floors | Concrete ground floor, T&G boarding on timber joists above | Dampness, deflection, timber condition |
| Roof | Timber trusses with felt and concrete tiles | Tile condition, felt deterioration, water ingress |
Potential hazards & inspection priorities
The most significant risks associated with Arcal houses relate to localised decay of the timber frame and sheathing. Deterioration can occur where moisture has penetrated the external render or where detailing has allowed prolonged damp exposure.
Corrosion of metal trim strips, metal window frames, and foil-backed plasterboard linings is also a recognised issue. If left unmanaged, these defects can contribute to wider fabric deterioration.
Is this house right for you?
An Arcal house may be suitable for purchasers who understand non-traditional construction and are prepared to assess condition carefully rather than relying on age or appearance alone.
- Condition of the timber frame and external render is critical
- Evidence of ongoing maintenance should be reviewed
- Allowance should be made for repair and renewal of original components
Mortgage & resale considerations
Mortgage acceptance for non-traditional properties is influenced by construction type, condition, and the clarity of professional reporting. Lender criteria can vary and may change over time.
Clear survey findings, documented maintenance, and the absence of unresolved structural or moisture-related defects are commonly influential factors.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition and construction of an Arcal house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
- Identify visible deterioration to timber frame elements and external render
- Assess signs of dampness, moisture ingress, and condensation risk
- Comment on roof coverings, drainage, and external envelope condition
- Review the general condition of accessible floors, ceilings, and structural components
- Highlight defects requiring repair, monitoring, or further investigation
However, there are limitations to what a survey can determine without intrusive investigation.
- Confirm the condition of concealed timber sheathing and framing
- Assess hidden structural elements behind linings or finishes
- Determine the full extent of moisture-related deterioration within wall panels
- Inspect areas that are inaccessible at the time of inspection
Where higher-risk indicators are identified, further specialist or intrusive investigation may be recommended.
For a thorough building survey in Greater London, an instant quotation can be obtained through the online survey calculator.
Considering an Arcal house?
A detailed building survey can help clarify construction-specific risks before committing to a purchase.
Get your instant survey quoteDisclaimer: This article is provided for general educational purposes only and is based on industry research, professional knowledge, and experience. It does not relate to any specific property and should not be relied upon when making a purchasing decision. Prospective purchasers should always commission an independent RICS-qualified surveyor to conduct a full inspection and provide a report on the actual condition of any property of interest.
