Walsh employs around 175 people across London and the South East and has worked on most of the capital’s major infrastructure schemes delivering aggregate supplies, earthmoving and transporting demolition waste.
The acquisition takes the total number of GRS Group staff beyond 800.
The two businesses will operate more than 50 sites and are expected to handle over 20m tonnes of construction aggregate and other materials each year.
Walsh will continue to operate as a standalone business, joining forces with GRS when it works for customers to do so.
Walsh directors Nick Walsh, Westley Pickup, Richard Walsh and Tim Wheeler will continue to operate the business day-to-day.
Nick Walsh said: “This agreement is a win-win. We’re very proud of the reputation Walsh has built up over the years – that’s a testament to the brilliant team we have working for us.
“The decision to sell has not been taken lightly, but teaming up with a business as ambitious as GRS is a natural step to take the company on to the next stage in its development.”
It provdes the GRS Group with access to key strategic locations in the heart of the capital for the import and export of bulk materials, while giving Walsh access to GRS’s national network of customers, supply partners and facilities for construction waste.
GRS Chief Executive Jon Fisher, said: “The two businesses have worked together on many projects and in recent years we’ve built a much closer working relationship.
“More important is that Walsh has a similar customer-led, can-do attitude as we have in GRS, so I’m confident we’ll work well together.”