A small room with a big moisture load
Bathrooms are small, so people expect painting one to be quick and cheap. Often it is. But a bathroom with gray or black spotting on the ceiling, around the tub or behind the toilet is a different job. The spotting has to be dealt with, and its cause understood, before new paint goes on, or it comes straight back. This guide explains what moves the price.
What Iowa's mold guidance says about surfaces
Iowa's state public health mold guidance (reviewed March 18, 2019) says moldy non-porous surfaces such as concrete, tile or vinyl flooring can be wiped with a mild household detergent solution, while porous materials such as drywall and carpeting should be removed, discarded and replaced; it says bleach is not necessary unless the intent is to disinfect.
That guidance shapes the job. Spotting on a sound, painted surface is cleaned. Drywall that has grown mold into the paper is a different matter: under the state's guidance it should be removed and replaced, which turns a paint job into a repair job, and the price changes with it.
The moisture behind it
NOAA's engineering weather data for Sioux City puts the average annual latent (drying) cooling load at 19,349 Btu/cfm against a sensible cooling load of 8,678 Btu/cfm, with the largest latent loads in July (7,242) and August (6,680). Latent load is the share of cooling work that goes into taking moisture out of the air. Those are the Sioux City station's figures, quoted as NOAA gives them.
Moist outdoor air adds to the steam from every shower. In a bathroom without a working exhaust fan, that moisture settles on the coolest surfaces, often the ceiling and the outside wall, and that's where spotting starts.
Cleaning and drying
How much cleaning the room needs is the first driver. A few spots near the tub take minutes; a ceiling covered in them takes longer, with careful rinsing so no residue is left for paint to sit on. Then the surfaces must dry fully. A crew may clean one day and paint the next, which adds a visit.
Drywall repair
Where the paper face of drywall has been stained through or has gone soft, sections may need cutting out and replacing, then taping, finishing and sanding before any primer. Each of those steps needs drying time, so a repair can stretch the job over several days. Ask how repairs are priced, and whether you'll see the damage before they start. Our drywall repair and surface preparation guide explains the stages.
Primer and finish
Stained areas take a stain-blocking primer so the marks don't bleed through. The finish is usually a paint sold for bathrooms, often with a mildew-resistant coating and a sheen that can be wiped clean. Those products can cost more than ordinary wall paint, but they're the point of the job. Our paint sheens guide explains why bathrooms usually get a satin or semi-gloss finish.
The fan
Paint can't fix a room that stays wet. If there's no exhaust fan, or the one there doesn't clear steam, the spotting will return. Some painters will point this out and suggest an electrician; it's outside their trade. Fixing ventilation first protects the money you spend on paint.
A small room is slow per foot
Bathrooms have more edges than walls. Cutting in around a tub, a vanity, a toilet tank, mirrors, towel bars and tile takes far more time for the area than rolling an open wall. Fixtures may need removing and refitting. That's why a bathroom often costs more per square foot than a bedroom.
Ceilings
The ceiling is usually where mildew is worst, and it's the hardest surface to clean and paint well. If it's textured, cleaning and priming take longer still.
Comparing proposals
- How the spotting will be cleaned, and what happens if drywall is damaged.
- Drying time allowed before priming.
- The primer and finish products named.
- Whether fixtures are removed or painted around.
See our interior painting page and pricing guide for more.