Short answer: what to use in humid rooms
For rooms that are humid but not directly splashed (many bathroom ceilings and walls, laundry rooms, some kitchens), moisture-resistant or mold-resistant drywall is the usual upgrade over standard board. For surfaces that get direct water, such as shower and tub surrounds, drywall of any kind is generally not the right base. Cement board or another product made for wet areas is the common choice there, and the manufacturer’s instructions for your tile or wall system should have the final say.
No drywall is waterproof. Better boards slow down moisture damage and give you more time. They do not replace ventilation, good waterproofing details, or fixing leaks.
Why standard drywall struggles with humidity
Standard drywall is a gypsum core faced with paper. Both parts take up moisture, and the paper is an organic material that mold can feed on. If you want the background on that, see is drywall porous.
Prolonged dampness can soften the core, make the paper separate from the board, and cause ceiling panels to sag. Damp board also tends to hold fasteners poorly. An industry Q&A from the Association of the Wall and Ceiling Industry makes a similar point: gypsum board is easily affected by water and high humidity, and its guidance centers on keeping the board dry and controlling the relative humidity of the space.
The main board types
- Standard drywall. Fine for dry living areas. Not a good choice where steam or dampness is routine.
- Green board (water-resistant board). Paper facing treated to absorb less moisture. Often used in bathrooms and similar areas. It is a modest upgrade and is generally not recommended for direct water contact.
- Mold-resistant paper-faced board. Often sold in purple or other colors under various brand names. Marketed as offering more mold and moisture resistance than green board. Check the product data sheet for the specific claims and test ratings.
- Paperless or fiberglass-faced board. Replaces the paper with a glass-mat facing, which removes the paper food source for mold. Typically costs more and can feel rougher to work with, so follow the maker’s finishing advice.
- Cement board. A cement-based panel used as a tile backer in wet areas. It does not rot or soften the way gypsum does, though it still needs proper joint treatment and, in many systems, a waterproofing layer or membrane.
Brand names and availability vary by store and region, so check what your local supplier stocks. Product lines change over time.
Which board for which room
| Location | Commonly used board |
|---|---|
| Bathroom ceiling | Moisture- or mold-resistant board, plus a working exhaust fan |
| Bathroom walls outside the wet zone | Moisture- or mold-resistant board |
| Shower and tub surround | Cement board or another wet-area backer system, per the tile and membrane instructions (see what type of tile to use on shower walls) |
| Kitchen | Standard or moisture-resistant board; ventilate cooking moisture |
| Laundry room | Moisture- or mold-resistant board |
| Basement walls | Depends on moisture history. See below |
Basements need extra caution. If the wall can get damp from a foundation leak or wet concrete, drywall is a risky finish even in a resistant version. Fix the water source first (see water leaking through a foundation or basement), and consider whether a material that tolerates moisture is a better fit.
Moisture-resistant is not waterproof
This is the most common misunderstanding. Resistant boards are designed to take some humidity and the occasional splash. Standing water, a leaking pipe, or a poorly sealed shower will still damage them. If a panel gets soaked, plan to inspect it, dry the cavity, and in many cases replace the wet section; how to fix a ceiling after a leak walks through that repair.
At what moisture level does mold grow?
There is no single magic number, because mold needs moisture, a food source, and suitable conditions together. A general indoor rule of thumb from public health guidance is to keep indoor relative humidity below about 60 percent, and many sources suggest roughly 30 to 50 percent. Wet building materials can support mold growth within a day or two if they stay wet, which is why quick drying after a leak matters.
If you want a number for the board itself, a moisture meter gives you a reading, but readings differ by meter and material, and no universal pass or fail standard exists for gypsum board. Treat a meter as a way to compare wet and dry areas of the same wall.
Will a dehumidifier dry out drywall?
A dehumidifier lowers the humidity of the air, which can help damp materials dry over time and helps prevent new problems. It is not a fast fix for drywall that was truly soaked. Saturated board that stays wet for more than a day or two often needs to be cut out, and the cavity behind it dried properly. Combine dehumidifying with air movement and with fixing the source of the moisture.
Installation details that matter
- Use the screws recommended for your framing. See coarse vs fine drywall screws for wood versus metal studs.
- Keep the bottom edge of the board slightly off the floor in damp areas, following the manufacturer’s guidance, so it does not wick water.
- Finish joints and seal or prime the surface with products suited to wet rooms.
- Install and use an exhaust fan that vents outdoors, not into the attic.
- Fix leaks, condensation and drainage issues before closing up a wall.
When to call a professional
- Mold covering a large area. The US EPA’s guidance suggests considering professional help when mold covers more than roughly 10 square feet.
- Mold inside wall cavities, or recurring after cleaning. The moisture source has not been found.
- Wet walls near wiring or outlets. Turn off the circuit at the panel before touching anything, and call an electrician if you are unsure the area is safe.
- Older homes. Joint compound, texture and some old wall materials may contain asbestos. Do not sand, cut or demolish suspect material until it has been tested by a qualified lab or professional.
- Structural concerns. Rotted framing, sagging ceilings or signs of ongoing leaks from above should be assessed before you re-board.
FAQ
What are the three types of drywall? People use that phrase differently. A common grouping is standard, moisture-resistant (such as green board), and fire-rated or specialty board. Mold-resistant, paperless and cement boards add further options for wet areas.
Does Lowe’s offer waterproof drywall panels? Large home centers generally stock moisture- and mold-resistant boards and cement board. Stock varies by store, and truly waterproof wall systems are typically assembled from several products rather than one drywall panel. Check the product listing and data sheet.
Is blue board the same as moisture-resistant board? No. Blue board is made for veneer plaster. See blue board vs drywall.