Joist hangers too big for joists?

[robinbanks]

I think you're getting into the weeds a bit too much and worrying about something that will only ever be noticed while you're doing the job and obsessing over it. Don't let strangers in the internet egg you on too much; one joist that is 3mm high on the middle of a floor, with joist spacings of 400mm, you're never going to notice it. Close your eyes and walk across your new floor. 100% there isn't going to be a certain point where you catch the sole of your shoe on the "high spot" on the floor and fall over - human walking processes simply don't require anywhere near that level of precision from the travelled surface

 

[danlightbulb]

I think you're getting into the weeds a bit too much and worrying about something that will only ever be noticed while you're doing the job and obsessing over it. Don't let strangers in the internet egg you on too much; one joist that is 3mm high on the middle of a floor, with joist spacings of 400mm, you're never going to notice it. Close your eyes and walk across your new floor. 100% there isn't going to be a certain point where you catch the sole of your shoe on the "high spot" on the floor and fall over - human walking processes simply don't require anywhere near that level of precision from the travelled surface

Yeah you're right of course. I don't do these things every day so its hard to know as a DIYer trying to do a good job, how much accuracy should be accepted. If you're doing this every day then you know what is and isn't sufficient, and how to solve certain problems (like a sagged ceiling) or when to ignore them.