Crown prosecutor Anna McConachy said the woman had bought a number of properties before and knew her way around a sale-and-purchase agreement.
She knew the vendor was fully insured and that if something happened to the property between the signing of the agreement and the settlement date, she could effectively gain an empty section, minus the burnt house, for $70,000.
McConachy described it as a sophisticated plan but one the defendant needed to improve her financial situation, despite being asset-rich.
While initially the woman was buying the house for her son to live in but things changed, which meant he could potentially no longer be the tenant.
New Zealand also went into lockdown and the woman wasn't working and was relying on the wage subsidy for income.
McConachy said the woman was "strapped for cash" and her son's future was up in the air.
McConachy said if it weren't for CCTV footage that put the woman leaving the house last year, just minutes before the fire was noticed, she might have got away with the alleged crime.
"Consider her circumstances, consider her son's circumstance ... it all points to this being a deliberate fire."
McConachy said the woman said in a text message she was in Tauranga but CCTV footage and phone data showed she was not and did not go to Tauranga until later.
"Her lying is a clear attempt to distance herself from the property that burnt down, to create an alibi and deflect attention away from herself," McConachy alleged.
"There was not one piece of direct evidence but when you combine the threads of evidence it points to her guilt."
The woman's lawyer, Andy Hill, said there were two fire experts who gave evidence in the trial and they had differing views on how the fire started.
The Crown's expert said it was deliberately lit, while the defence's expert said the cause was undetermined.
He said for that reason alone, the jury should find the woman not guilty.
"If they are at loggerheads, what chance do you have?"
Hill said if the jury thought the explanation of the defence's expert witness was valid, the trial should stop there and the woman should be found not guilty.
Hill said there was overwhelming evidence that showed his client was "100 per cent committed to this deal".
She had said she had started to move some of her son's furniture into the house, including clothing and family photos.
Hill questioned whether the woman would be so "callous she wants to torch" her son's personal and sentimental property.
Hill said the woman had also made multiple future plans for the property.
Hill asked the jury to consider whether she would have bothered doing this if she was a "calculating criminal mastermind".
"Think about it from a human level and apply your common sense to it. None of it makes any sense whatsoever."
Hill showed the jury the large sale and purchase agreement and said the woman would have had to read it from cover to cover to find the relevant clause about insurance - which Hill said he had trouble understanding.
"There are holes riddled throughout that theory."
Hill said the woman was not cash-strapped as she had $1.2 million in assets and although she didn't have disposable income, she didn't need it.
"If you apply common sense you can see this case for what it is ... and reach the conclusion you should reach of not guilty."
Judge Hollister-Jones was expected to sum up the case to the jury today before jury members retire to consider a verdict.
