The Plumbers, Gasfitters and Drainlayers Board says the economic downturn has made people more willing to complain about work they've had done.
The board's annual report shows a 20% rise in complaints during the past financial year.
Gasfitting work was the subject of the most complaints - 41 in the year to April 2010.
Plumbing and non-registration drew about 25 complaints each during the same period.
Most complaints were laid by members of the public, followed by councils and tradespeople.
The board believes the rise in complaints is due to consumers becoming more discerning during the recession, and more prepared to contest an invoice.
The board says it now spends half of its revenue dealing with complaints.
