We're not gonna lie: the narrative point of view in this book is weird. Really, really weird. We actually have three different narrative techniques that work together here. So let's break them down and see what we've got.
First, we have Shukhov himself as a narrator. Shukhov often narrates using the first person. And we often hear his direct, inner thoughts, which are usually offset by the lack of a subject. In other words, when we hear Shukhov's thoughts, the subject of his sentences is often implied. If you are thinking about what you need to do today, you probably don't think in complete sentences; your thought would be something like "Need to buy some milk," with the "I" being implied. Here's an example of Shukhov doing that:
Down into the mixing room. Can't just leave the trowel lying around. Might not be brought out tomorrow. (690)
So we have first person, and implied subjects. Shukhov often speaks directly to the audience using the second person "you." Though it is debatable as to whether or not he's actually addressing anyone directly, like Ferris Bueller. When Shukhov uses "you" it could sometimes be a way of psychologically distancing himself from his awful situation, so that the bad stuff is happening to some sort of distant "you" and not to him directly. And Shukhov also sometimes uses "you" when he's silently addressing another person in his head.
On top of all of this, we also have a limited omniscient narrator who uses the third person. This limited omniscient narrator is "limited" because we only have access to Shukhov's inner thoughts, not the thoughts of all the characters. This narrator tells us what Shukhov is doing and sometimes what Shukhov is thinking/feeling, even though Shukhov often does this himself. What's truly weird about these narrative points of view is that they switch back and forth constantly, even within the same paragraph.
If there was one thing Shukhov couldn't endure, it was these spectators. Trying to wangle himself an engineer's job, the pig-faced bastard. Started showing me how to lay blocks once. Laughed myself sick. Till you've built one house with your own hands, you're no engineer. That's how I see it. (596)
So within one paragraph we have a narrator talking about Shukhov in the third person; a sentence with an implied subject; a first person address from Shukhov; and a second person address from Shukhov. Sheesh. In some ways the lack of a break between different styles of sentences mirrors Shukhov's stream-of-consciousness thought process, which means that his thoughts tend to jump around to different things constantly.