Green board is similar to standard drywall. It's called green board because of the green paper on both sides, but has the same core as ordinary drywall. The green paper imparts moisture resistance, whereas white paper on standard drywall transmits water to the gypsum core.
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Green board is not waterproof. It's designed to be used in place of ordinary drywall for damp areas, such as bathrooms, laundry rooms, basements or any area with a higher moisture content than average. The area behind the toilet, or on the ceiling in the bathroom, are good examples of green board application.
The green color allows for better visibility of drywall compound when installing green board.
Green board, also sometimes referred to as indoor tile backer board, can be used as a tile backer for household use, but only on walls that do not have direct exposure to splashing water. Direct exposure to water can damage green board.
Green board is not recommended as tile backer in shower or tub enclosures, or for walls and ceilings in swimming pool enclosures, steam rooms or saunas. Doing so can result in the failure of the project.
Use Cement Board Instead
Use cement board as a tile backer in tub or shower enclosures, saunas or anywhere tile or surrounding areas come into direct contact with water. Cement board has a water-proof cement core that won't swell or deteriorate in the presence of water. Recognize cement board by it's dark color and heavy feel.
Cement board dust can contain silica. Breathing it can cause cancer or lung damage. Wear breathing and eye protection when working with cement board.
Green Board Types
Green board is available in 1/2-inch, and 5/8-inch thicknesses -- the same as standard drywall -- except that drywall has a thinner, 1/4-inch thickness not offered in green board. Use 1/2-inch for an average installation, use 5/8-inch for a more heavy-duty application.
Green board, even though it's the same thickness, shouldn't be confused with Type-X drywall, which is a fire resistant product used behind kitchen stoves, for example.
Install Green Board
Things You'll Need
- Drywall square
- Utility knife
- 1 1/4-inch bugle head screws
Green board handles, cuts and installs the same as standard, white gypsum drywall.
Measure and use a drywall square to mark the green board along the cut-line.
Score the green board along the line with a utility knife -- make a shallow cut -- and snap or break it along the line.
Screw the green board to the wall or ceiling studs using a drill/driver and 1 1/4-inch drywall screws, spacing screws no further than 6 inches apart, countersinking the head of the screw slightly below the surface of the paper.
Green board panels can be installed horizontally, vertically or a combination of both directions.
When green board is installed on an exterior wall, or a "cold space" such as above an uninsulated crawl space, the insulation between wall studs falls within standard insulation practices, which typically rely on R-30 insulation for minimum heat loss.