So I asked a question a couple of days ago about leveling my ceiling joists. I got great recommendations, from strapping with 1X3 straps, and also metal studs.

So I placed String Lines across and found out I have a max of half an inch difference from one joist to another. There are actually 2 joists right next to each other that are lower than others by 0.5 inch (the third and 4th joist from the left in the picture).

So my question is: Will the imperfections be noticeable if I decide not to correct this before drywall placement? Thank you. enter image description here

  • Are those joists sloping at an angle (low side above the doors; high on opposite end)? If so, what is the difference at the high end? Mar 6, 2019 at 1:36
  • 1
    Use drywall shims.
    – Mazura
    Mar 6, 2019 at 1:40
  • The low side is actually in the middle area. Right above the door, they are all level, I just put a 12 ft LVL beam across the door you see there, so all the joists are level there. All those 6 joists are supported by the beam I installed. But as you move away from that area, the two joists (3 and 4 from the left) have bowed down half an inch. At the other end, they again level out, no bowing.
    – alemiss
    Mar 6, 2019 at 1:51
  • I believe there is a kind of flooring that requires a very level, very horizontal subflooring. I don't know if that might be relevant for your situation, but if so, you could call a flooring store and ask them for the specs. They might say that horizontal to within half an inch is fine. Mar 6, 2019 at 2:57
  • aparente001, this is for my ceiling joists, not floor joists. This is also a one story home, no floors above.
    – alemiss
    Mar 6, 2019 at 2:59

1 Answer 1


It's hard to say, I find myself noticing every imperfection that I'm responsible for. I don't easily notice imperfections in other people's work unless I'm looking for them. It looks like your joists are on about 24's so 1/4 inch per foot dip in the middle might not be too noticeable as long as it's level'ish above the doors. The doors offer a reference to level, very close to the ceiling so they are the primary area of focus.

Keep in mind 1/4 inch per foot is plumbing drain slope.

I'd definitely go with 5/8 drywall especially if you on 24's and shim where necessary. And avoid drywall seams around the areas in question.

It boils down to who it's for. If it's your house and you can live with it, it's fine. If it's a customer you're going to have to consider what they'll think.

Try having a look at other ceilings in the house or a friend's house and see if you notice any dips and then check with the big straight bar.

  • Great advice Joe Fala, thanks. Yes I was thinking about 5/8 drywall. But didn't know about the seams around these joists. I will heed your advice. This is actually a house I just bought, remodeling it for myself. I will live in it. And yes they are 24 on center.
    – alemiss
    Mar 6, 2019 at 2:32
  • I'm glad I could help. You could also try pulling the low joists up by laying a long peice of timber across the top of the joists and attaching the low joists to it and pulling it up. I'm not confident in that advice as I'm not a roofer and I don't have much experience with roofing but I would give it a try.
    – Joe Fala
    Mar 6, 2019 at 2:47
  • Oh I did sort of that today. The reason for the bowing, I found out, was actually the gusset plates (basically the plywood) on the truss joints got weaker (they were stapled) on those joists. This allowed the adjoining studs that connect inside the gusset plates to come apart and also bow down. What I did was, build a support wall, attempted to jack it up very gently to re-align the misaligned studs, clamped the gusset plates together, then screwed an 18 gauge plate onto the plates for extra support.
    – alemiss
    Mar 6, 2019 at 2:57
  • Sound like you know your framing and roofing much better than me! Are you going to be drywalling and taping? Drywall isn't to hard but taping is very difficult. I've gotten pretty good at it but even nearly perfect ceilings are a challenge.
    – Joe Fala
    Mar 6, 2019 at 3:02
  • Yes, that is my plan. I have lots of time to do the work. It's more like a weekend deal for me. If I do the drywall and screw it up, I guess I will find someone to take it down and do it over. But my plan is to do it myself. Thanks
    – alemiss
    Mar 6, 2019 at 3:06

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