These stain-fighting tips will hide an unsightly water stain on your ceiling and stop the leak that caused it.

Photo: istockphoto.com

Q:

Recently, I noticed some water stains on the ceiling of my living room. There are some stains on the ceiling now, and I am not sure where they came from. How can you cover them up? Is it safe to assume that whatever caused the stains is no longer a threat to my house now that they are dry?

A: Water staining on the ceiling occurs when water seeps through the ceiling and evaporates, leaving an unsightly mineral deposit.

Covering up a water stain without fixing the leak can result in additional staining on the ceiling, as well as more severe structural or electrical damage. Even if the stain no longer exists, it is vital to locate the source and repair it as soon as possible.

Identify and repair the cause of the stains, then clean, prime, and paint over the water stains to restore your ceiling’s blemish-free finish.

STEP 1: Identify and repair the root cause.

When dealing with a water stain, your first priority should be to determine the source of the leak (or in rarer cases, the flood) that caused it-the roof, the upstairs radiator, and the upstairs bathroom are good places to start.

• You can detect leaks in the roof by inspecting crumbling shingles, compromised flashing (the weatherproofing material installed on the roof), or compromised seals around roof vents. It may be necessary to replace the roof if the leak cannot be patched.
• Check for leaks in the radiator body, valve, pipe, or bleed point (where cold air escapes from the radiator).
• Replace old caulking in the upstairs bathroom that may be letting moisture in and encouraging leaks. Ensure that overflowing toilets are repaired and clogged sinks or showers are unclogged to prevent floods.

You can prevent future leaks on your ceiling by making the necessary repairs, or by hiring a professional roofer, HVAC technician, or plumber as necessary.

STEP 2: Clean the stain with bleach.

As soon as you’ve addressed the underlying issue, you can tackle the stain itself, beginning with a thorough cleaning. You can remove any lingering mildew, grease, dirt, or dust from the stained area of the ceiling by cleaning it with a mild bleach solution (one cup bleach and three cups warm water).

Photo: istockphoto.com

A drop cloth should be placed on the floor above the ceiling stain, and a ladder should be propped up to reach it. Put on protective gloves and goggles, climb the ladder, and wipe down the stain with a clean sponge dipped in bleach. After rinsing off the bleach solution with water from a spray bottle, wipe the damp area with a clean cloth. Cover the ceiling trim with painter’s tape once the ceiling is completely dry to protect it from primer and paint.

STEP 3: Apply a base coat of stain-blocking primer.

You may be tempted to slap a coat of paint directly over the water stain at this point. Due to their water-soluble nature, interior latex paints are not a good choice for a base coat over a water stain. Water stains dissolve into wet latex paint layers as the paint dries, causing the discolored mineral contents of the stain to show through the paint to the ceiling surface.

You should use an oil-based, mold-resistant, stain-blocking primer closely matching the existing ceiling color as a base coat to cover water stains on the ceiling. Water stains cannot bleed through oil-based stain-blocking primers (such as KILZ Stainblocking Ceiling Paint, available on Amazon). As opposed to latex paint, these stain-blocking primers contain a high amount of binders (polymers that bind paint pigments), so they can adhere to the surface for a long time.

Depending on your ceiling style, you will need to apply primer (and paint). If you have a smooth ceiling, roll the primer over the water stains using a paint roller with an extension and a ⅜-inch nap roller cover, then let the primer dry for two hours or as instructed by the primer packaging. If you have a textured ceiling, opt instead for a thicker nap roller cover (¾ -inch to 1-¼ -inch nap) or spray on the primer using a can of stain-blocking primer.

STEP 4: Cover the primer with ceiling paint.

Primed areas of ceilings are usually a few shades lighter or darker than the rest, which can draw the eye to stained areas. During the painting process, the primed area will be color-matched with the rest of the ceiling for a professional-quality finish.

A latex (water-based) or alkyd (oil-based) ceiling paint can be applied over an oil-based primer, but latex paint dries faster and emits fewer volatile organic compounds (VOCs). Make sure you purchase ceiling-specific paint, which is usually thicker than traditional paint and comes in a non-reflective finish to hide small imperfections.

Choose a paint that matches the color of your ceiling for a uniform look, then apply it over the primed area with a roller (choose a ⅜-inch nap cover for a smooth ceiling, or a ¾ -inch to 1-¼ -inch nap for a textured ceiling). For even coverage, let the first coat of paint dry for up to four hours or as directed by the packaging.

The ceiling should look as if there were never any water stains after the second coat dries.