The rate will rise again to £14.99 from January 2012 following the deal for workers employed under the Joint Industry Board for Plumbing and Mechanical Engineering Services.
The agreement covers 10,000 workers directly but the deal will also be used as a benchmark for other employers in the sector who are not part of the Joint Industry Board, meaning up to another 10,000 workers could benefit.
The deal will see a 3% increase to rates and allowances from January 2011 and the same again from January 2012.
There are also improvements to average holiday pay and from 2012 overtime will commence from 37.5 hours rather than the current 39 hours.
Unite national officer John Allott said: “This agreement is in the best interests of both workers and employers. It secures two years of pay increases but allows employers to control their costs during a time of massive spending cuts.
“Crucially, it maintains the integrity of the national agreement which ensures that there is stability across the industry.
“We will be using this deal in future negotiations in the construction sector to show that it is both possible and necessary, for the sake of recruitment and retention to ensure that the skills and dedication of construction workers are recognised even during difficult times.”