The hall did not know when he had last been checked on.
Soon after, a Select Committee Inquiry into student accommodation was launched, where it was discovered that Pendrous' death was just the tip of the iceberg.
The committee heard about understaffing and lack of training among the halls staff, and poor processes for at-risk students.
That is something a former residential assistant (RA) at a Christchurch student hall knows all about.
She finished her role late last year, and was exhausted by the end of it.
"It just felt like it never ended, like I was always dealing with hard things," she said.
"I ended up taking a week off work and just talking through some of the things that I'd been through."
At 19 years old, she had 42 students under her care.
She said the pressure to respond to emergency situations every weekend caused burnout for her and many of her colleagues.
"I'd have to take a resident to the hospital, and I'd be at the hospital for a couple of hours, and obviously that takes quite a bit out of you.
"Then I'd come back and then I'd start my shift and I'd have another six hours."
Under the new code of practice accommodation providers must make sure staff have ongoing training in mental health support, suicide awareness, and drug and alcohol use among students.
They must also have clear emergency plans in place.
The University of Canterbury is confident its halls of residence are meeting these standards, after making improvements since 2019 when Mason Pendrous died.
First-year student Molly moved into a hall of 480 people a month ago, and attends compulsory weekly check-ins with her RA.
Even when she went to isolate elsewhere with Covid-19 in her third week living there, her RA kept in contact.
"My RA messaged me a couple of times when I was in lockdown just to check how I was going, because obviously, they have a really important job of making sure everyone feels okay."
Molly said the transition away from her family home had been a big step and the support on offer is essential.
As tertiary providers grapple with the new code, New Zealand Union of Student Associations president Andrew Lessells is keeping an eye on progress.
He is concerned they are not involving students in the design of wellbeing and safety plans.
But he said a six-month buffer period is in place before they face consequences for breaches.
"This is the first time the tertiary sector has ever had a code like this, and we do know that it's going to take a transition period for people to get used to it.
"We are sort of waiting for that six-month period before we become too critical of providers."
Lessells said students and RAs in halls could not afford another year of poor welfare support, and expected to see necessary changes in place come July 1.