An unlicensed builder with prior convictions for working without a licence who accepted tens of thousands of dollars in payments for either incomplete or poor work has been fined $105,000.

56-year-old Peter Wotton of Burnside pleaded guilty to counts of accepting payment for services and failing to provide them in a reasonable time and carrying on business as a building work contractor without a licence.

In a prosecution launched by Consumer and Business Services, the Elizabeth Magistrates Court was told Wotton had accepted payments from four consumers of between $1,300 and $47,000 for a range of building services, including installing sheds, fencing, pools, automatic doors and outdoor bathrooms.

In each case, he either failed to complete the work or did such a poor job that consumers were forced to hire another contractor to perform remedial works.

"In one instance, a consumer paid more than $32,000 to Wotton to build a pool, only to learn the fencing wasn't straight, the filter pump wasn't secured to the ground and the pool itself had a crack in the bottom - damage so bad the consumer was told it would be cheaper to install a new pool than repair the crack," Commissioner for Consumer Affairs Dini Soulio said.

"To make things worse, this isn't his first offence.

"Wotton has form - he has prior convictions for similar offending, and clearly knew he was engaged in unlawful behaviour."

In addition to the $105,000 fine, Wotton has been disqualified from managing corporations for a period of eight years.