A large Palmerston North family which lost their youngest and oldest members to a house fire were hindered in their escape routes from the second storey, a coroner has found.
Bessie Tokona, 61, and six-year-old Eunice Felton, died in the Housing New Zealand home on Exeter Cresent early on September 3, 2015.
A fire investigation report concluded it was likely the fire started on the back elements of the stove.
During the inquest, the mother, Nechia, said unprompted that she'd left the element on after spotting cannabis.
The admission left her "extremely upset and crying".
Spotting cannabis is a method of smoking the drug, typically using heating it between two knives.
Mr Scott said Nechia had turned both the rear elements on, one by mistake, when she spotted her cannabis.
"There is no other explanation for how the element came to be on."
There was evidence a pan of cooking oil was often left on the back element with a lid on when not being used.
The coroner's report says is probable the pan caught fire because both elements were turned on full.
Nine others in the family managed to escape, thanks to the "brave and unselfish" actions of one family member, Kohi.
Coroner Tim Scott said if not for Kohi's actions in getting the family out so fast, "my investigation would probably not have been confined to inquiring into the deaths of only Bessie and Eunice".
He couldn't determine why the pair didn't make it out, but both were vulnerable members of the family and would have needed help.
All but two of the family members slept upstairs, and once the fire had started, Kohi was "largely responsible" for getting the family out of the burning building.
"Once they were out, he organised a head count and realised that Bessie and Eunice were missing."
The house had 11 fire alarms had been installed by HNZ, only nine were found following the fire. There was no evidence of a fire escape plan.
Mr Scott raised concerns about the window latches on the second floor and the removal of a wooden fire escape which wasn't replaced.
The latches were designed for safety to stop children falling from an open window, but Mr Scott says this made it "much harder for whanau to exit from the upstairs".
Fire and thick smoked stopped them leaving from the internal stairs and they had to break the windows to get out.
Some family members jumped from the upper storey, while others used a wooden fire escape permanently fixed to the side of the house.
However, the house did once have a second wooden fire escape which was taken down because it was rotting. It wasn't replaced.
HNZ says the reason for that is it is their policy to make fire escape routes "user-friendly for all people" including the elderly.
Mr Scott said he understood the rationale behind the latches and ladder, but did not accept it.
While they didn't make for any other deaths, Mr Scott said they "might have done".
"When it comes to a fire surely the more escape routes the better, even if some of these cannot be used by all people all of the time," the coroner's report reads.
"It seems to me that in a respect of a fire, safety catches on windows are potentially death traps."
He said HNZ's alternative suggestion of a barrier in front of windows at least 760mm high to make climbing difficult would be a "better option".
Mr Scott says an escape plan would have put in place actions to help Bessie and Eunice get out.
However, "the plan would probably have failed simply because by the time anyone realised the house was on fire, it was full of dense smoke and the internal stair exits were blocked.