What Are the Causes of Bubbling in Drywall?

Hire a professional installer if you are inexperienced with drywall.

The paper surface of drywall, as well as drywall tape and joint compound, can all form bubbles if they're damaged or improperly installed. Bubbles may not be noticeable during installation, but once the wall is painted, the imperfections will become more pronounced. You can prevent bubbles if you act quickly and appropriately.

Tape Installation

The edges of each sheet of drywall are tapered to allow the tape and joint compound to create a smooth, level surface. If too little compound is placed beneath the tape before installation, the tape won't stick to the wall and will rise up to form bubbles once the top layers of compound are applied. Wrinkled tape will also create surface bubbles, and should be removed and replaced during installation.

Joint Compound Application

Bubbles in joint compound are usually the work of inexperienced installers. Compound that hasn't been mixed thoroughly or powdered varieties with too little water added to the mixture won't spread evenly over seams. To smooth out bubbles on still wet compound, you can dip a drywall knife in water and run it over the surface. If the bubbles are noticeable after the compound is dry, you can rent a drywall sprayer and apply a layer of texture over the entire wall to hide imperfections.

Sanding Process

Joint compound must be applied to seams and corners in three layers, and sanded between each application. If the seams are not sanded smooth, bubbles will appear within the compound. If bubbles are present in each coat, they may be impossible to remove completely. To remove surface bubbles, you can lightly sand each seam just until it's smooth. Additional sanding could break through the still delicate layers of compound and make the bubbles worse.

Excess Moisture

Drywall installed near a water source is usually water-safe to prevent wall damage. If nonwater-safe drywall gets wet, the layer of paper on the surface expands and then dries, leaving bubbles. A good coat of primer and paint reduces bubbling due to water damage, and exposed drywall is especially susceptible. You should always use an appropriate drywall type, depending on the location of the wall, and prime and paint each panel immediately after installation.

References

• "Drywall: Professional Techniques for Walls & Ceilings"; Myron R. Ferguson; 1996