The Firmcrete House

The Firmcrete house is a form of system-built property developed during the 1960s in response to post-war housing demand. Manufactured by Firmcrete (London) Ltd, approximately 2,000 units were constructed, primarily within urban and suburban housing developments.

These are generally two-storey dwellings with flat roofs finished in bituminous felt. Construction combines timber frame wall panels to the principal elevations with brick flank walls, giving the houses a distinctive appearance within estates of similar period housing.

A typical Firmcrete house with flat felted roof, tile-hung upper elevations and brick flank walls characteristic of this 1960s system-built design.

Firmcrete houses are typically two-storey in form. The front and rear elevations are formed using storey-height timber frame panels clad with plywood up to first-floor level and tile hanging above, backed by building paper. Internally, plasterboard linings are fixed to the frame with insulation positioned between studs.

Flank walls are constructed as 9-inch cavity walls formed from two leaves of 2-inch chemically impregnated cement-bonded chipboard slabs (Firmcrete slabs), with the cavity infilled with reinforced concrete. The separating wall between adjoining properties follows a similar 9-inch cavity arrangement with reinforced concrete infill.

Ground floors are concrete slab construction. First floors comprise timber boarding laid on timber joists. The roof structure consists of timber joists supporting 2-inch Firmcrete slabs, insulation and a bituminous felt covering, together with an internal gutter system.

Some variants were constructed with flank walls rendered throughout rather than combining brick and render finishes.

A primary consideration is the condition of the reinforced concrete within the cavity walls. Carbonation and corrosion of embedded steel can lead to cracking, spalling and progressive structural weakening.

Flat felted roofs are vulnerable to deterioration if not regularly maintained. Failure of the waterproof covering or blockage of the internal gutter system can result in persistent moisture ingress, affecting both structural and internal elements.

Insulation levels are generally modest by current standards, which can contribute to reduced energy efficiency. Single-glazed windows, where still present, further impact thermal performance.

Given the 1960s construction date, asbestos-containing materials may be present within certain components. Identification and management require appropriate specialist assessment.

Firmcrete houses form part of the UK’s system-built housing stock and require informed assessment. Understanding the reinforced concrete elements, timber framing and flat roof detailing is essential when considering purchase.

• Review the maintenance history, particularly roof coverings and concrete repairs
• Look for evidence of cracking, spalling or previous structural works
• Confirm that any asbestos risks have been appropriately managed

Condition and maintenance history are central factors when assessing suitability.

Lender criteria for system-built housing can vary. Decisions are typically influenced by construction type, overall condition and clarity of professional reporting.

Documented repairs, absence of significant structural deterioration and evidence of ongoing maintenance will commonly influence lending and resale prospects.

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

• Identify visible cracking or spalling to reinforced concrete elements
• Assess signs of dampness, moisture ingress, and condensation risk
• Comment on roof coverings, internal gutter systems, and external envelope condition
• Review the general condition of accessible floors, ceilings, and structural components
• 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 internal condition of concealed reinforcement within cavity infill
• Assess hidden structural elements behind finishes or linings
• Determine the full extent of carbonation within reinforced concrete
• 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.

For a thorough building survey in Greater London, an instant quotation can be obtained through the online survey calculator.