Mold in Bathrooms: What Washington Law Says and What to Do

Mold in a bathroom is a moisture problem that shows up as a stain. Black spots on caulk and grout are a ventilation and cleaning issue; mold behind tile, under a vanity or on the ceiling around a fan usually means water is getting somewhere it should not. This page covers what the law in Washington does and does not say about mold, what the EPA and the state Department of Health (DOH) advise, when to bring in help, and what a remodel should change so the mold does not return.

What the law says, and what it does not

There is less mold law than most people expect.

• No federal limits. The EPA says no federal limits exist for mold or mold spores, so a test cannot be used to check compliance with a federal standard.
• State guidance, not a home standard. The DOH mold pages give cleanup guidance and refer residents to their local health department. They do not set an indoor mold limit for homes. If you need a ruling on a specific situation, Clark County Public Health is the local office to ask.
• Landlords must inform tenants. RCW 59.18.060(14) requires landlords to give tenants information provided or approved by DOH about the health hazards of indoor mold, including how to control mold growth, in writing or posted, at the start of a tenancy. DOH adds that landlords are responsible for maintaining rental units, "including fixing building problems such as water leaks".
• The seller disclosure has no mold question. Washington's statutory seller disclosure form (RCW 64.06.020) does not ask about mold. The nearest items ask about wood destroying organisms or pests (4.H), environmental substances such as asbestos and lead-based paint (7.E), and "any other existing material defects affecting the property that a prospective buyer should know about" (9.A).

Small patch or bigger problem?

DOH draws the line by size and location. A small area is "less than about ten square feet, or a patch three feet by three feet square." Most people can clean that themselves. The EPA uses the same ten square foot line.

DOH also says: "You don't need to sample for mold because in most cases you can see or smell mold." The EPA adds that porous items such as ceiling tiles and carpet "may have to be thrown away if they become moldy". In a bathroom, that includes moldy drywall and insulation.

Moisture control is the fix

The EPA's summary is one sentence: "The key to mold control is moisture control." For a bathroom that means:

• Dry wet areas fast. The EPA says to dry water-damaged areas and items "within 24-48 hours to prevent mold growth."
• Keep humidity down. EPA: indoor humidity "below 60 percent (ideally between 30 and 50 percent) relative humidity."
• Vent to the outside. The EPA says to use exhaust fans "to remove moisture to the outside (not into the attic)."
• Run the fan long enough. HVI advises at least 20 minutes after a shower; the Department of Energy's Building America guidance says one hour and recommends a timer switch instead of a standard wall switch.
• Fix slow leaks. A dripping supply line or a failed toilet seal feeds mold out of sight. Signs to look for are in hidden water damage in bathrooms.

Hiring help for mold

DOH is blunt about this trade: "There are no specific certification requirements for performing mold/water damage restoration in Washington State." "Anyone can call themselves a "mold remediation specialist" without having any specialized training or credentials." DOH advises making sure the contractor is licensed, bonded and insured. In Washington terms, that means checking the company's contractor registration in L&I's Verify tool, as described in checking a bathroom contractor's credentials.

Ask any mold company two questions: where is the moisture coming from, and who will fix that? Removing mold without stopping the water source means paying twice. If the source is a failed shower pan or a leaking drain, the repair is plumbing and waterproofing work, and it may need a permit.

Mold and insurance

Washington's Office of the Insurance Commissioner says: "Many homeowner policies offer limited mold coverage, but only when the mold results from a covered loss", and "it's usually very limited." Mold from a sudden pipe burst reported promptly may be part of a claim; mold from a slow shower leak usually is not. The distinction is explained in water damage, homeowners insurance and your bathroom.

What a remodel should change

When mold is found during demolition, the remodel is the chance to remove the cause, not just the stain:

• Remove wet and moldy materials and let framing dry before closing the wall.
• Rebuild the shower with a continuous waterproofing system, not just tile and grout. See bathroom waterproofing explained.
• Install a fan that meets the state code, ducted directly outside, with controls that make it run long enough.
• Put the hidden-damage repair in writing. Mold and rot found behind walls are a change order, as described in bathroom contracts and change orders.

JDI's planning ranges include waterproofing, the fan and electrical work, but not unexpected structural repair found inside walls, which we handle by written change order. To talk through a bathroom that keeps growing mold, start with our Vancouver bathroom remodeling page.