TWA scheme manager Ruth Soundarajah said the decision was taken reluctantly.
“We provided very reasonable notice of our intention to set this deadline. We do not want any mixed messages out there about the integrity of our scheme,” she added.
The TWA did not name the companies concerned, but said it would continue to work with them to help them comply.
Members are given six months from joining the scheme to gain certification for their factory glazed timber windows through third-party testing, audits and factory inspections.
