Why Is Vinyl Flooring Turning Blue Near My Tub?

The blue color typically comes from moisture trapped under the vinyl reacting with the backing, the adhesive, or a dye in the underlayment. Some vinyl products contain colorants that turn blue when wet for a long time. The stain is not mold or mildew, which usually looks black or green.

A leak from the tub's caulking, the drain pipe, or the overflow plate is the most common culprit. Water wicks under the flooring and sits there, causing the reaction. If you notice the stain growing after showers, that is a strong clue the tub is leaking.

• Check the caulk line around the tub for gaps or cracks
• Inspect the overflow plate for loose screws or signs of rust
• Look for water stains on the ceiling below the bathroom
• Feel the floor near the tub for soft spots or give
• Wipe the area dry and see if the blue returns within a day

Until you find and fix the leak, keep the area as dry as possible. Wipe up any standing water after showers and avoid using the tub if you suspect a significant leak. If the leak is from a pipe, turn off the water supply to the tub if you can. You might need a plumber to repair the pipe or replace worn seals.

Drying the subfloor is critical to prevent further damage. If the leak is recent, you can use fans and dehumidifiers to dry the area. For a long-standing leak, the subfloor may already be damaged, and you might need to remove the vinyl to let it dry properly.

Once the leak is fixed and the floor is dry, take steps to keep water away from the vinyl. Re-caulk the tub edge with a waterproof sealant, and re-seal the overflow plate if it is loose. Use a bath mat outside the tub to catch drips, and wipe up spills quickly.

Check the caulk and grout around the tub every few months for cracks. If you live in Quincy, keep the bathroom well-ventilated to reduce humidity, especially during the cold, snowy months. A dehumidifier can help in a bathroom without a window. These small habits can prevent the blue stain from returning.