How to prevent and repair bubbling paint
In your case you have a good idea that the problem might be moisture and you know where it might be coming from. To confirm your suspicion – or as a first step if there is no obvious explanation – use a moisture meter such as B. the digital pen model from General Tools ($36.97 at Home Depot). Or get a pinless gauge or one that toggles between pinless and pinless, like the General Tools combo model ($54.97). (Pinless operation is easiest to check a general area; pens are great for finding a problem.)
First take a measurement where the color is intact; it will likely be between 5 percent and 15 percent, depending on the relative humidity in your home that day. Then check the drywall where the paint is peeling. If this reading is significantly higher, examine the area to determine where the ceiling or wall is damp and where it is dry. You may discover a trail of moisture leading to a water leak, a roof problem, or even a drainage problem outside of your home. Whatever the scenario, fix the moisture issue before addressing the color.
Condensation forms on heating and air conditioning ducts when warm, moist air meets a cold surface. If the condensation forms in only one spot, there may be a gap in the insulation around the ducts or a leak between duct sections. If you’re comfortable crawling around in your attic, you can try to pinpoint the cause by looking for dirty insulation that will show where mold is growing due to the moisture. Replace any missing insulation.
If a duct seam is leaking, apply duct sealant ($8.67 for 10.5 ounces from Master Flow at Home Depot), which works better than foil tape for sealing ducts in attic conditions. Apply the mastic with a caulking gun, but smooth down the bead with a gloved hand, brush, or spatula to ensure the material fills the gap.
If home improvement in the attic isn’t your thing, hire an HVAC company to inspect and repair the ducts. Also ask the company to ensure the system is properly calibrated, with no clogged vents or a dirty filter. A company that provides airtightness and insulation services can address common attic conditions that may make condensation worse by plugging gaps where indoor air enters the attic and where the insulation is too thin to be effective .
If you rule out moisture as the reason your paint is peeling, there are numerous other possible explanations. Scratch off a bubble or two to see if only the last layer of paint is peeling off or if the mistake extends all the way to the beginning. You may even find a layer of drywall mud between two coats of paint, a sign of a previous repair.
If only the last coat of paint is peeling off, the surface could have been dirty, preventing the new paint from adhering well, or being too hot, causing it to dry too quickly. Indoors, high temperatures are most likely to cause color problems where the sun is shining on a wall; General room temperature can be fine, but the surface can be well above the maximum of 85-90 degrees stated on the color label. Paint can also fizz when someone paints directly over new drywall or a patch of drywall without first priming. The drywall soaks up so much of the first coat of paint that the next coat of paint can’t adhere well.
Whatever the cause, preparing for a new paint job starts with scraping the blisters and wiping the surface. If it might be dirty before the last coat, clean it with soapy water and then with clean water. Greasy walls and ceilings can cause major problems in kitchens. Let the surface dry and then inspect. If it’s not smooth enough to repaint, apply a thin coat of light drywall slurry, allow to dry, then smooth down with 100 or 120 grit sandpaper. Or you can use a damp, stiff sponge, which you often rinse in a bucket of water and wring out well, to avoid dust formation. Remove all sanding dust or wait for the wall to dry. Then prime the surface, wait the time recommended on the label and repaint.
If moisture was the culprit and you’ve fixed that issue, follow the same process to prepare the surface for paint. However, use a stain-blocking primer to ensure no stains from the previous leak migrate into your new paint.
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