A cement board has many varied uses in home construction and is often preferred over greenboards or blueboards in certain areas of the house. That said, greenboards and blueboards are also often and equally used in home construction and are, sometimes, a better alternative. While all three boards can be used for almost the same purpose, they are considerably different from one another. Here are some of the main differences between these two types of boards.
Composition and Size
Cement boards are made up of cement and glass fibers. These are available in 4×8-foot and 3×5-foot sheets that are either 1/2 inch or 1/4 inch thick.
Greenboards or blueboards, on the other hand, are types of drywall. Essentially, drywall is gypsum pressed between two sheets of paper. It was developed to replace lath and plaster construction. While typical drywall uses standard paper, greenboards use a moisture-resistant, green-colored paper. Blueboards, similarly, have a blue-colored paper covering, designed specifically to adhere to plaster. These boards are available in 4×8 and 4×10-foot sheets and are 1/2 or 5/8 inch thick. However, both greenboards and blueboards have gypsum cores.
Durability and Installation
Cement boards are far more durable and impact-resistant than blueboards and greenboards, which are both made from gypsum. However, cement boards are far heavier than greenboards and blueboards, making installation difficult for DIY projects. In fact, cement boards are best installed by professionals.
Cement boards are available in two types: water-resistant and waterproof. Greenboards, on the other hand, are only water-resistant due to the green-colored moisture resistant paper. Since there core is still gypsum, greenboards cannot be waterproof. Blueboards are made of gypsum and do not have any moisture-resistant paper covering; this makes them neither waterproof nor water resistant.
Water resistance is an important criterion because exposure to water will result in the formation of mold and mildew, leading to eventual rot and breakage. Water resistance also determines the manner in which these boards can be used.
Cement boards are best used outside the house as siding or in wet areas inside the house such as bathrooms and kitchens, due to their durable and water resistant/waterproof nature. Further, when using tiles, cement boards are the best underlayment because they offer a smooth surface and help the tiles adhere better. In fact, greenboards and blueboards should not be used for wet applications and as tile backing boards.
That said, greenboards are water-resistant and hence can be used for damp applications, such as un-tiled bathroom walls and basements. They are best used in areas of the house that are affected by humidity and occasional water spray.
Blueboards are somewhat water-resistant but not waterproof, and preferably should not be used for wet or damp applications. In fact, blueboards should only be used as an underlayment for veneer coat plastering, which is what the blue-colored paper is designed for.
All three boards are very different in their composition and uses, so there is no true way to compare them. It is best to choose a board based on requirements and location.