Aiming to expand its reach to professional contractors, Home Depot (HD) announced it will be acquiring GMS Inc. (GMS) for $4.3 billion or $5.5 billion when including debt.

Home Depot bought SRS Distribution — the subsidiary that’s acquiring GMS — last year for $18.25 billion, in the largest acquisition in its history. Texas-based SRS sells supplies to professionals in the landscaping, roofing and pool businesses and it has bought up many other smaller suppliers as it’s grown.

A subsidiary of Home Depot’s SRS Distribution Inc., the supply company it bought last year, will start a cash tender offer to buy all outstanding shares of GMS for $110 per share. The total equity value of the transaction is approximately $4.3 billion. The deal is worth about $5.5 billion, including debt.