The decision on the breaches concerned "quality of work and delivery of services", the association said. Its chief executive, David Kelly, said the RMBA "expects all members to maintain the highest standards".
"Alleged breaches of the code of conduct are taken very seriously and RMBA will act in full accordance with the rules of the membership under the constitution where it may be the case that members are falling short of these standards," he said.
Cranston told the Weekend Herald he was "extremely disappointed".
"I've been a member of Master Builders for 23 years ... we've won numerous house of the year awards and been one of [the] leading builders in that organisation for 20 years," he said.
Cranston blamed the company's woes on a series of leaky building claims that began five years ago.
"Rather than run away like a lot of other builders and ignore them and leave customers in the lurch, we've dealt with over $4 million worth of leaky building claims. That severely hurt our financial position and has meant we have been going through some tough times," he said.
"It's cost us in the millions, it's cost us a lot of money which we could have walked away from. It was actually my allegiance to Master Builders and my standing in the organisation that meant I felt I should not run away from them."
The tough position the company was in meant there were delays for some projects that led to some complaints.
Cranston, however, said the company always produced "a very high standard of product".
He had been close to resigning from the association because of the way they dealt with the complaints, he said.
He thought the association should support members and help them through issues.
Because of the pressure the leaky building claims had put on Cranston Homes, the company had also proposed a compromise with creditors, under which they would get paid 50c in the dollar.
"We had two choices, we either shut the door and leave everyone with nothing or we try to do a compromise with our creditors," Cranston said.
"We want to stay in business and want to look after our creditors as much as we can."
Creditors are owed about $1.5m and Cranston said about 80 per cent viewed the compromise "very favourably". Cranston said it was his intention that if creditors could be paid back more, they would be.
"The timing of Christmas is terrible and I feel terrible about that, but that's just the reality of it," he said.
One small business owner owed tens of thousands of dollars by Cranston Homes told the Weekend Herald he wasn't accepting the compromise.
The money represented two years of "blimmin' hard work".
"That's my profit," said the man, who did not wish to be identified.
Another tradesperson did not wish to be interviewed but said in an email: "The outstanding money he owes my company is substantial, without it we face like very tough times. Try telling your kids there is no Christmas then working out where I'm going to find money to pay the mortgage," the man said.
However, one creditor who contacted the Weekend Herald defended Cranston.
"We are very disappointed and frustrated but, to be fair to Blair himself, he has helped so many of us years back when we were starting up. And I know he put a considerable amount of his own money into his business, besides the time he contributed to Master Builders' work," the man said, on the condition of anonymity.
" ...we can see Blair is trying to do his best to save the business and to get us paid ... many would have quit by now and left all to a third party to handle. Blair faced all of us and answered all difficult questions ... I must say this itself is quite incredible. I think despite the overall situation, Blair is quite an honourable man."
