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.

Home Depot is buying specialty building products distributor GMS for $4.3 billion, emphasizing a deliberate push by the home improvement chain into building and materials supply.