Trad was formed in 1971 and has grown to become the largest privately-owned scaffolding contractor in the country.
Trad employs 450 people and has a turnover of £45m from its focus on scaffolding work across London and South East alongside a national hire network.
The Trad Group will continue to operate from the current locations around the UK and be run by the existing management team.
Hayden Smith remains as Group Chairman, Des Moore as Group Managing Director and Alan Skeats as Group Financial Director.
No value for the deal has been disclosed.
Smith said: “Opportunities have been numerous over the years to sell the Trad Group but were never seriously considered as it would have led to changes in our successful management team followed by the loss of our long established and well respected identity.
“The Altrad Group offer made it very clear that they wanted the Trad Group but were very insistent that the team stayed intact long term to continue with our successful strategy of providing quality service and materials which is instrumental in both client satisfaction & retention.
“I am very impressed on this focus by the Altrad Group and my team and I are all very motivated going forward to continue our profitable growth with the knowledge that we have the full support of not only a major manufacturer of access products but a successful group with the same ethos which creates success”.
Ray Neilson MD of Altrad Belle UK said: “This acquisition forms part of the bigger plan to provide the large UK market with products and services from Altrad who specialise in the manufacturing and sales of scaffolding, cement mixers and wheelbarrows, together with providing additional contracting services in the scaffolding sector”
Previous UK acquisitions by Altrad include BarOmix, Belle Group, Beaver 84, NSG, Generation and MTD.
Altrad is keen to continue with its expansion plans and wants to hear from companies that are interested in joining the group if they are involved in any element of scaffolding, cement mixers or wheelbarrows -preferably with a turnover in excess of £10m.