Mostyn Bullock, principal engineer at research body Chiltern International Fire, said student accommodation blocks could be "deathtraps".
Mark van Scalwyck, an insurance inspector for Zurich Municipal, said: "Most of the defects we find relate to cavity construction.
"About one in four properties have problems with fire stopping."
The workmanship problem may also affect other types of buildings, but timber frame buildings are most at risk because cavities are lined with combustible materials. This means the timbers can smoulder undetected for hours before bursting into flame.
The findings have led to insurers to warn that they may refuse to pay for fire damage where poor workmanship has led to a blaze spreading.
The danger was discovered after a fire test at BRE's Cardington test facility on a six-storey timber frame building.
The timber frame industry has responded by calling for building control officers or independent consultants to sign off the correct installation of fire stops in cavities.