Arrowtrim Houses

The Arrowtrim house, also known as the Prowting house, is a form of system-built housing developed in the late 1960s. These properties reflect a period of rapid construction innovation in the UK, intended to deliver conventional-looking homes using modernised building methods.

An Arrowtrim house showing brickwork at ground floor level with tile hanging above, typical of this system-built construction.

Arrowtrim houses are most commonly encountered as bungalows or two-storey semi-detached and terraced houses in suburban locations. The external appearance is deliberately traditional, masking the underlying system-built structure.

Substructures are formed with concrete strip footings supporting a concrete slab ground floor. External walls are of platform timber frame construction, formed using storey-height timber panels.

Externally, the timber frame is sheathed with plywood, covered with a breather membrane, and then separately clad in brickwork. In many examples, brickwork extends to first floor level with tile hanging above, fixed to timber battens.

Internally, walls are lined with plasterboard, with mineral fibre insulation between timber studs. Upper floors are timber joisted with timber boarding, while ceilings are plasterboard. Roofs are of timber truss construction, finished with bituminous felt and tiled coverings, with mineral fibre insulation at ceiling level.

The primary concern with Arrowtrim houses is the long-term performance of the concealed timber frame. This was evident during inspection where moisture pathways exist around openings, roof junctions, and external cladding interfaces.

Failure or deterioration of the breather membrane can allow moisture to track into the frame, increasing the risk of rot and decay. This is a common issue in properties of this type where maintenance has been inconsistent.

Thermal performance can also be compromised by thermal bridging and degraded insulation, leading to increased heat loss and condensation risk. The potential presence of asbestos-containing materials, depending on later alterations, also requires consideration.

An Arrowtrim house may be suitable for purchasers comfortable with non-standard construction that is dependent on ongoing maintenance and effective moisture management.

• Commission a full building survey
• Ensure previous repairs and alterations are documented
• Budget for potential insulation or cladding-related upgrades

Lender acceptance for Arrowtrim houses is generally influenced by condition, maintenance history, and the clarity of professional reporting. Construction type alone is not usually the determining factor.

Evidence of a dry, well-maintained timber frame and absence of unresolved defects can materially influence mortgage and resale outcomes.

A building survey provides an informed assessment of the visible condition and construction of an Arrowtrim house. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.

• Identify visible signs of moisture ingress and external envelope failure
• Assess the condition of roof coverings, insulation, and drainage details
• Comment on internal finishes where defects indicate underlying issues
• Review accessible structural elements and floor constructions
• 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 frame elements
• Inspect areas hidden behind linings or external cladding
• Determine the full extent of hidden decay or moisture damage
• Assess inaccessible roof voids or covered structural areas

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.