"GoHabsGo" wrote

About half of the cold room is above grade and there are a couple of vents
to the outside which means it will get very cold in there in winter but
the builder only put an interior door in place, with no insulating value.

Not all that good then if I understand you and the 'interior door' faces the
outside.

If that is the case, replace the door (might need to re-frame as interior
ones may be as small as 22 inches (minimum I've ever seen) while exterior
tend to be larger).

I don't know the Ontario code specs but it's likely you wont find an
exterior door there that isn't within them.

I have something like that here in Virginia. Code allows an interior type
door if leading to an enclosed porch. Problem is that 'enclosed porch' can
be just screen enclosed. I replaced the problematic one that leads into the
house proper but have not yet replaced the one that leads to the garage
(garage to house proper has an exterior door).

Want really odd? I get grief over an exterior door *inside* the house
proper that used to be the back of the house before the enclosed porch was
added (leads to enclosed porch portion with another exterior door now
applied). Codes can be pretty odd so I mention it only if you may have same
issues and it's an interior door. That way you can check to see if you
create an issue.