Step 1: Replace the Insulation

Using a drywall saw, cut through the ceiling drywall to expose the cause of the stain; in this case, the stain is caused by condensation from the air-conditioning refrigerant line (Image 1).

Remove old insulation. Measure a new piece of polyethylene insulation and cut it to size. Secure to the refrigerant line with tape (Image 2).

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    Image 1

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    Image 2

Step 2: Replace the Drywall

With the pipe properly insulated, patch the hole in the drywall. After squaring off the hole, install a 2" x 4" cut to length into the existing ceiling. The 2" x 4" will provide a base for attaching the drywall patch (Image 1). Measure the new section of drywall and cut it to size with a utility knife. Slide it in place and secure with screws (Image 2).

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    Image 1

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    Image 2

Step 3: Match the Paint

If the ceiling is textured, use a scraper to scrape off the stucco finish around the seam (Image 1).

Tape off the seams with drywall tape and apply a first layer of joint compound. Allow the first layer to dry, sand smooth and apply a second layer. Repeat as needed (Image 2).

Finish the patch by matching the stucco pattern on the ceiling and painting with a matching ceiling color.

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    Image 1

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    Image 2