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How to repair a water-damaged ceiling

MitchellMc
Bunnings Team Member
Bunnings Team Member

Difficulty: Beginner

 

Repairing a water-damaged plasterboard ceiling involves fixing any peeling paint or cracks and removing water stains.

 

Once you have identified and addressed the source of the water damage, you can follow this simple step-by-step guide to make your ceiling look like new.

 

If you need any help with repairing your ceiling, please don't hesitate to ask. We're here to help.

Steps

Step 1

The first step is to track down the source of the ceiling leak.

 

Possible sources could include a broken roof tile, inadequate roof flashing or even a leaking water pipe. It’s important to have these issues addressed before preforming any repairs to the ceiling. 

 

After addressing any active water sources, allow the damaged area to dry thoroughly. This is especially important in ceiling cavities as mould can develop behind the plasterboard.

 

For significant leaks, open up the ceiling and use a fan or de-humidifier to dry the residual moisture. 

 

1.1 Water dripping from leaking ceiling.png

 

Step 2

Chip away any cracked paint or crumbling plaster using a putty knife. Clean up the area and remove any compromised material.

If there was a minor leak and the only damage was stained paint coating, then prime the area with a stain blocker and apply a fresh topcoat of paint.

 

2.1 Cracks and damaged plaster.png  2.2 Chipping loose paint away.png  2.3 Loose paint removed.png

 

Step 3

Apply a small amount of plaster filler to the affected area using a putty knife.

 

Force the filler into any holes, cracks and depressions. Leave it to dry fully before proceeding. In warm weather, this may only take a couple of hours, but in cooler areas, it could take up to 24 hours.

 

3.1 Applying plaster to damaged area.png  3.2 Spreading plaster with wide scraper.png  3.3 Plaster drying.png

 

Step 4

Us120-grit sandpaper and a sanding float or block to lightly sand back the filler until it is flush with the surrounding plasterboard.

 

Next, apply more filler over the entire damaged area using a putty knife. Do this sparingly.

 

Ensure this filler is only slightly proud of the surface. Wait for it to dry before sanding back flush with the surface using the 240-grit sandpaper.

 

Inspect for any areas you might have missed or any inconsistencies. Repeat this process until a uniform surface is achieved.  

 

4.1 Sanding plaster back flush with ceiling.png

 

 

Step 5

Apply self-adhesive reinforcement tape to areas where the plasterboard is cracked. 

 

Next, apply filler over the tape before allowing the filler to dry completely. Sand the excess filler back with 120-grit sandpaper until the tape begins to show.

 

Then, apply a thinner coat of plaster over the area and extend it out into the surrounding ceiling.

Note it is not possible to disguise a crack that requires tape by simply plastering over the taped area. You must extend the plaster into the surrounding ceiling to taper it off and provide a transition.

 

5.1 Adding reinforcement tape.png  5.2 Tape applied.png  5.3 Applying plaster over tap.png  5.4 Spreading plaster with wide scraper.png  5.5 Extending plaster out away from crack.png  5.6 Plaster drying.png

 

 

Step 6

Remove excess plaster using a sanding float and 120-grit sandpaper.

 

Once the area is smooth, switch to 240-grit sandpaper and finish. You might require another fine skim coat of plaster to remove any imperfections.

 

6.1 Sanding excess plaster.png  6.2 Second sanding with finer paper.png

 

 

Step 7

After the filler is completely dry, apply a stain blocking undercoat to the damaged area with your rollerIt is important for the undercoat to have stain inhibiting properties as water stains tenaciously bleed through paint coatings.

 

Allow the undercoat to dry. 

 

At this point, any imperfections in your plasterwork will become evident. Fix them by filling or sanding the areas and then applying another layer of undercoat.  

 

7.1 Applying stain blocking undercoat.png  7.2 Undercoat applied.png

 

 

Step 8

Apply pre-paint mould treatment to the damaged area with a spray bottle or by wiping over with a cloth.

 

Next, apply two coats of your ceiling paint over the damaged portion.

 

In some instances, it might be necessary to paint the whole ceiling. If this is the case, treat the immediate area with pre-paint mould spray before proceeding.

 

8.1 Applying pre-paint mould treatment.png  8.2 Applying ceiling paint.png  8.3 Ceiling paint applied.png

 

Materials

  • Stain inhibiting primer 
  • Ceiling paint 
  • Plaster filler 
  • Self-adhesive reinforcement tape. 

Tools

  • Putty knife 
  • 120-grit sandpaper
  • 240-grit sandpaper 
  • Sanding float or block 
  • Paint roller and tray 
  • Spray bottle or cloth.

Images

1.1 Water dripping from leaking ceiling.png  2.1 Cracks and damaged plaster.png  2.2 Chipping loose paint away.png  2.3 Loose paint removed.png  3.1 Applying plaster to damaged area.png  3.2 Spreading plaster with wide scraper.png  3.3 Plaster drying.png  4.1 Sanding plaster back flush with ceiling.png  5.1 Adding reinforcement tape.png  5.2 Tape applied.png  5.3 Applying plaster over tap.png  5.4 Spreading plaster with wide scraper.png  5.5 Extending plaster out away from crack.png  5.6 Plaster drying.png  6.1 Sanding excess plaster.png  6.2 Second sanding with finer paper.png  7.1 Applying stain blocking undercoat.png  7.2 Undercoat applied.png  8.1 Applying pre-paint mould treatment.png  8.2 Applying ceiling paint.png8.3 Ceiling paint applied.png

 

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