Saint-Gobain, which currently has the Isover insulation brand, said the acquisition improved its insulation offer for new segments such as flat roofs and floors.
It also strengthened its insulation business in the new construction and renovation markets.
Hadleigh-based Celotex, which makes rigid polyisocyanurate (PIR) insulation for floor, wall and roof applications, will continue to operate under its brand name and with its existing management team.
Completion of the acquisition is subject to approval by the Office of Fair Trading.
Celotex achieved a turnover of £69.7m during its last fiscal year ended August 2011. It has 170 employees and recently extended capacity with a new £3m distribution and innovation centre in order to support its growth on the construction markets.
