Deal set to wrap up next year
Kingspan is paying €251m (£216m) for a majority stake in in natural insulation and wood-based building envelope products manufacturer Steico.
The Germany-based business posted revenue of €445m (£382m) last year and earnings of €90m.
It has four production sites in Poland France and is set to post revenue this year of €378m.
Kingspan said it has an option to buy another 10% stake in the firm in the future with the initial deal for the 51% stake set to be rubber-stamped by early next year.
The Irish building materials firm is due to release its interim results on 18 August.