This is the house I live in St 53BT in the neighborhood called Boeung Tum Pun, in the unit on the far right. It’s four stories, and Christian university students from an indigenous tribe live on the top two floors. They get up there by a metal stairway coming from the right side of the covered entrance yard at ground level.
I have the ground floor and a second or mezzanine floor. Notice the building is one-room wide, what is called a pteah lveng in the local dialect. A building like this is built for one family, with a shop or restaurant or small business on the ground floor, but landlords block the inside stairways to upper floors and add the outside external stairs so they can house two or more families in the building.