Family-owned Standard Industries, which owns roofing companies Icopal and SGI and Siplast, said on Thursday it would offer 25 euros in cash per share for Braas, a 15 percent premium over the stock's closing price before news of the planned offer emerged.

A takeover deal would create an entity with $5.1 billion of annual revenue and 15,000 employees that combines Braas' focus on pitched roofing, used mostly for residential buildings, with Standard Industries' flat roofing products for commercial buildings in Europe.

Braas shareholders 40N Latitude SPV-F Holdings, an investment vehicle of Standard Industries, and Monier Holdings, a consortium including Apollo, TowerBrook, York, have already agreed to tender their combined 40 percent of shares in Braas to Standard Industries.

Braas had flagged Standard Industries' planned offer on Wednesday and said its board of directors viewed it as too low.

Standard Industries said its offer, which is not conditional on a minimum acceptance level, was fully funded by available liquidity.

($1 = 0.8894 euros)

(Reporting by Maria Sheahan; Editing by Georgina Prodhan and Victoria Bryan)