Companies including Aviva and Axa warn that modern construction method has too high a fire risk

Insurers could pull cover for completed timber-frame buildings amid growing concerns over safety and the spiralling costs of claims.

The warning follows a surge in the number of fires in large timber-frame buildings. Recent figures suggest that 40% of fires that provoked a loss of more than £150,000 involved structures built using modern methods of construction, which included timber frame and light gauge steel frame.

The figure is based on data compiled by RISCAuthority, a research and lobbying body for the insurance industry. It follows a report by the Association of British Insurers in December that found commercial fire claims were running at a 20-year high.

Allister Smith, property risk manager at insurer Aviva, said the firm was suffering “disproportionate losses” from large buildings built using modern methods of construction.

He warned that premiums could rise or cover could be pulled. “There may come a day when some materials will be challenged; the risk assessor will say we are not prepared to take that risk.”

His calls were backed by Douglas Barnett, head of customer risk management at insurer Axa, who said: “We’ve had massive concerns about this for five to six years. What we now have is the evidence.”

The insurers’ concerns centre on the performance of fire-stopping devices in cavities separating the frame from cladding in completed buildings. They say the combination of flammable timber and poorly installed fire barriers within the void means fires can spread easily inside the cavity and back into apartments.

The warnings come as RISCAuthority today handed a report to the London aassembly fire investigation panel warning about the risks of timber frame.

The assembly will begin a probe into the issue on 16 March. It was prompted by a fire in the Lakanal housing block in Camberwell in July, in which six people died, and two fires on half-built timber-frame schemes in the same borough since December.