Replacing Double Garage Sagging Ceiling & Cornices

I'm in the process of getting quotes for replacing the sagging ceiling and cornices of the double garage of an investment property (~20 years old). Garage has panel lift doors. Has anyone gone through this process and what was involved? Cheers.

I'm looking for the best value option, including rectifying the sag if possible.



  • +1 vote

    It depends on how bad the sagging is, but it is possible to jack the drywall up, or just use a 2x4 frame knocked into place, and then just re-screw the sagging gyprock.

    My experience has been that it’s better to try and find a handyman with some experience with this sort of work rather than a solid plasterer (not knocking solid plasterers at all) as plasterers will charge like a wounded bull, again IME, for this sort of job, whereas you might find a semi-retired builder or similar who can do the job for a lot less.

    No doubt you’ve already covered this but I’d also suggest getting quotes to just rip the whole lot out and start again, which is likely to be better in some ways as it’s just in a garage, rather than a home where sometimes it’s less messy to do the re-screwing rather than have all the crap from the roof space come down into the home.

    Either way, these days for a fairly uncomplicated job (spare the flushing which is a fine art and hard to DIY well) it’s going to prob be reasonably expensive, so try and get as many quotes as possible. Maybe even try the local messenger for builders and such who may just be looking for smaller jobs to supplement retirement income.

    Good luck with it.

    • +3 votes

      Qualified Plasterer here…

      I wouldn't suggest doing the above unless you are selling the property.

      Screws are not designed to hold the sheets up as the glue (Stud adhesive) is designed to do that.
      Screwing off sheets are merely there to hold the sheet while the glue dries and the glue is what holds the sheets in the long run.


        The paper is torn from the plasterboard what are you suggesting then.


          Without photos to see the extent of the sag, its hard to say.

          It sounds like the whole ceiling has given way and the cornice is the only thing holding it up.. Very common
          Without going into too much detail, you have two options:

          1: reapply glue from above and screw sheets back up. This depends on the integrity of the joins in the sheets and if there is any water damage or how ridged the plasterboard have become.
          You will need to apply the glue next to the existing glue whilst cleaning away ripped paper from existing glue. Be sure not to screw off the sheet too close to the glue or the screw heads will pop through the sheet when the glue dries as the glue will pull the sheet tighter to the ceiling.

          2: rip down the sheets and start again. You will be able to salvage the cornice most likely. Clean joists and put up the sheets complying with the guidelines.


          @skrep: Photos attached.



          Tiled or tin lid? there is no eaves on that side over the garage. The fascia gutter is against the brick work?
          The 2 conduit could be the problem causing water damage not sealed properly and letting water in through a penetration.
          Better guess Or there's an internal roof corner your valley is leaking spilling water over the top plate into the garage.
          If it's a high set house and you have a downpipe spreading on the lower roof to here best to move the drop

          Looks like about 3 meters at the most long from panel lift door. Find and fix any water leaks and I couldn't foresee problems only re screwing that small area.

          Make up a plate system like stonehenge to under prop then screw off


          Looking again this is in 2 places?
          Both have conduit going through and sagging where they both are.
          If you can call the sparky back and give him a massive serve and a bill.


          @hawkeye: Yes, sagging both sides of garage perpendicular to panel lift doors. Tiled. There are no eaves on both sides of the garage. Uploaded another pic, yes, fascia gutter is against the brick work.

          Looks like you might have nailed the problem.

          I'll see what the quotes say about fixing or replacing.


    Depending on whether the damage is to the drywall only or the roof frame. If the damage is to the drywall only, then I would get someone (or yourself if you know what you are looking for) to inspect your roof and make sure there are no leaks, that could be the source of your sagging ceiling problem.

    • +3 votes

      If there's no water stains good chance someone's been up there storing stuff or when Kev747 dud did the insulation program.
      The kids that didn't die didn't know how to walk on ceiling joists thuss rendering you a sagging ceiling.

      Without photos you might hopefully be able to pull it up to the joists with a couple of sticks and a flat plate across the ceiling and screw it off again.

      It's going to be a pain for any chippy to pull out insulation and start shooting more nogs in the ceiling especially closer to the outer frame.


    Could you remove the sagging ceiling and cornices?. Paint what's behind it.

    Would be the cheapest option.

    It seems odd that it would sagging. Got photos?


      Photos attached.


        Looks like just around the edge. Is that correct?

        Probabbly lack of support for the plaster board from the battens (or no battens) above. Possibly builder decided that cornices would be sufficient support.

        Is there insulation in the garage roof? If so then is it that loose fill blown-in stuff? I've seen that causing ceiling saggage before

        Possible solution - get some pine 2•4s , use them as bracing from underneath. Push the plasterboard up and attach 24s to the walls (drill holes into bricks, insert "spaghetti" . Pre-paint 24s before installing and then easy touch up afterwards. Would be the simplest and cheapest solution.


          Yes sagging is just around the edges. There are small bellies in the middle. There's a pic with the studs coming off the battens.

          I don't think there's insulation.


    Got this problem in my lounge room - bad sag in a corner extending a couple of metres out along the two walls…..former problem with leaky valley caused it I think. A plasterer tradie came and looked at it and said "too big for me as it'll have to come down and be replaced"……just hoping it holds on till the 12th of never when I get financial again.


    Call in your insurance. Could be caused by past water/storm damage.

    Once, in preparation of selling my property, I went to freshen the ceiling with a paint roller. As soon as I began the roller lifted the old paint off the plasterboard. I called in a plasterer to stipple the ceiling instead to cover the patches I'd made. He said to call in the insurance and claim for water damage. An assessor came and traced the water damage all the way down the hall and said it would be covered. I had no idea when this happened, could've been before I bought the place.
    I called back the plasterer who relined the entire ceiling of the house - I paid him cash to do the bedrooms, insurance covered the bulk of the whole new ceiling. Looked like a million dollars afterwards.


    From viewing the pictures I don't think it has any thing to do with water leakage or the sparkie. I did notice any eyelet hanging hook through the ceiling not far from the manhole. If this has been used to hang a full body boxing bag the constant punching and jaring with the weight of the bag on the beam would vibrate the plasterboard away from the stud work. If so it is an issue with the tennant. It should be able to be reglued screwed off and painted.


      Assessor went up manhole - fixing problem caused sagging. No water damage visible.

      To replace ceiling and cornices and coat of ceiling white is $3k.

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